Agreed: at a meeting of the methodological commission.

"__"___________ 2015

Lesson Plan #1.6

Topic studied in the program: PM 01

"Drilling holes, finishing holes (reaming)"

Lesson topic: Drilling holes.

The purpose of the lesson: Mastering and applying general cultural and professional competencies PC 1.2., OK 1., OK 5., OK 6.

To master the techniques and skills of students when drilling and reaming holes.

Educational goal: Careful attitude towards machines and tools and economical use of electricity. Save materials and work time. Accuracy and attentiveness in work. Proper organization of the workplace.

Material and technical equipment of the lesson: Posters, technological maps, samples, blanks, hand drill, electric drill, drilling machines, measuring tools, a set of drills and countersinks, countersinks, reamers and fixtures.

During the classes:

1. Introductory group briefing 50 min.

a) testing of knowledge on the material covered and the development of general and professional competencies. 15 minutes.

1. The meaning of drilling metal.

2. Equipment for metal drilling.

3. Tools and accessories for drilling metal.

4. The value of countersinking holes.

5. Selection of drills and countersinks.

6. Rules T.B. when drilling and countersinking metal.

b) explaining new material to students 30 min.

1. The importance of countersinking and reaming holes.

2. Equipment for countersinking and reaming of holes.

3. Tools and devices for countersinking and reaming holes.

4. Selection of countersinks and reamers.

5. Rules T.B. when drilling, countersinking, countersinking and reaming holes.

Drilling called - the formation of chips by removing a hole in a solid material using a cutting tool - a drill, performing rotational and translational movement relative to its axis.

Drilling is used to obtain a low degree of accuracy and

roughness - for bolts, adhesives, studs. etc.

Deployment called - increasing the size of the hole in a solid material.

Drills are separated - spiral, with straight grooves, feather for deep, annular drilling and centering. Drills are made from high-speed, alloy and carbon steels.

For drilling holes Spiral drills and less often special drills are used. The drill consists of a cylindrical working (cutting) part and a shank. The grooves serve to release chips. Based on the direction of the screw grooves, drills are divided into right and left. The drill moves counterclockwise and clockwise. Leftists rarely use it. The shanks of twist drills can be conical or cylindrical.

Tapered shanks - drills f 6-80mm.

Cylindrical - drills f up to 20mm (chuck).

Combination drills - countersink drill, reamer drill, tap drill.

When drilling use coolant - soap emulsion, rapeseed oil, a mixture of kerosene and castor oil.

Dull drill bits heats up quickly, (drill burnout) is determined by sound and heating,

Drill_sharpening - at an angle of 60°, with a smooth movement of the right hand, rotate around its axis without removing the drill from the circle. Sharpening is carried out with a cooling (water-soda) solution and finished on a block. Drilling is carried out mainly on drilling machines.

Hand drill, used for drilling holes up to 10mm.

Electric drills and pneumatic drills come in light, medium F up to 15mm and heavy type up to 30mm.

The following work is performed on drilling machines:

1. Drilling through and blind holes.
2. Drilling holes.

3. Countersinking - cylindrical and conical chamfer recesses. 4.3 anchoring - hole roughness class.

5. Reaming - precision hole roughness.

6. Cutting internal threads with a tap.

Drilling machines are divided into three groups: universal (general purpose). specialized and special. Universal ones include: vertical drilling and radial drilling machines. The spindle is located vertically or horizontally.

The universal vertical drilling machine consists of:

1.- foundation slab; 2nd column:

3.- table; 4- spindle head (inside the feed box and spindle speeds.)

5 - spindle, 6 - electric motor,

7 - drill feed handle.

The desktop vertical drilling machine 2M 112 is designed for drilling holes with an diameter of no more than 12 mm in small parts.

Drilling process - the main thing for workers is this rotational movement and translational movement along the axis of the drill is called the feed movement.

To ensure accuracy When drilling, the parts are secured firmly on the table in a vice or other device.

Cutting speed - depends on (part, brand, hole diameter, drill sharpening, depth feed and drill cooling)

When drilling, a distinction is made between through and deaf incomplete holes.

Drilling according to markings (they apply axial marks and the contour of the future hole) -

center punch.

Drilling is carried out in two steps (trial and final)

Countersinking . This is the process of processing with a special tool cylindrical and conical recesses and chamfers of holes for bolts, screws and rivets.

Countersinks have teeth at the end and are divided into cylindrical and conical and consists of: working part And shank

Safe working conditions when working with electric drills and drilling machines.

Use an electric drill only with rubber gloves and galoshes or a rubber mat under your feet.

1. Before turning on the electric drill, you first need to make sure that the wiring and insulation are in good condition, and that the voltage in the network is correct For this electric drill.

2. Turn on the electric drill with the drill removed from the hole, and remove the drill from the chuck after turning it off.

3.Recurrently observe the operation of the electric motor brushes; if there is sparking or smell or stoppage, the electric drill must be replaced.

When working on drilling machines.

1. Correctly install and secure parts and workpieces on the table.

2.Do not leave the key in the chuck after replacing the drill.

H. Do not handle the rotating spindle or cutting tool.

4.Do not remove the broken cutting tool from the hole by hand.

H. Do not press the feed lever too hard when drilling (small f drills).

b. Place a wooden pad on the table when changing a chuck or drill

7.Use a special wrench or wedge to remove the chuck, bushing, drill from the spindle.

8. Constantly monitor the serviceability of the cutting tool and the workpiece fastening device.

9.Do not work on machines wearing gloves.

10.Do not transmit or receive any objects through a working machine.

Necessarily stop the machine if:

1. Leaving the machine even for a short time, stopping work.

2. Detection of malfunctions in the machine, devices, cutting tools.

3.Lubricating the machine

4. Installation or change of devices and more.

5.Cleaning the machine, workplace and chips from the tool, chuck and workpiece.

V)consolidation of material from introductory briefing 5 minutes.

Mastering drilling in a lesson, where can you use drilling, countersinking, countersinking when repairing a car?

1. How to organize a workplace at a drilling machine, what safety rules must be followed when drilling?
2. How to drill a hole with a diameter of 6 mm in a steel part on a drilling machine when feeding the drill manually? At what approximate rotation speed should the machine be set?

3 . Why, when drilling on a drilling machine, must you first let it idle and then bring the drill to the part?

4. Determine, based on the tables, the optimal operating modes of the drilling machine (P— rotation speed, — feed) according to the following data: part material — steel with hardness 1-IB 180; drill with a diameter of 10 mm from high-speed steel P9.

5. In what sequence should I drill through holes in a part according to the markings on a drilling machine with mechanical feed of the drill?

1. Why the hole large diameter(10 mm or more) drilled in two working strokes?
2. How to control the drilling depth on a blind hole machine using:

a) depth gauge of a caliper?

b) measuring ruler of a drilling machine?

c) machine stop?

d) mark on the spindle sleeve of the machine?

l) thrust ring installed on the drill?

8. What are the reasons for the drill to “pull to the side” when drilling? How to avoid this?

9. Why does a drill sometimes squeak when drilling? How to avoid this? How to explain the strong heating of the chips and drill during drilling?

1. How to drill a hole in a part on a drilling machine using a jig?
2. What are the reasons for scratching on the surface of a drilled hole?
3. Why is cast iron drilled without cutting fluid?
4. What are the main reasons why drill bits break during drilling?
5. What safety rules must be observed when drilling on a drilling machine?
6. How to drill a hole with a drilling machine:

a) mild type?

b) average type?

16. What safety rules must be followed when drilling holes with a drilling machine:

a) electric?

b) pneumatic?

1. What are the basic rules for sharpening a twist drill?
2. What requirements must a properly sharpened drill satisfy?

19. What safety rules must be followed when sharpening drills?

2. Independent work students and ongoing instruction (targeted walk-throughs of workplaces). 4 hours

1. Drill and machine a hole with a diameter of 12mm.
2. Checking compliance with safety regulations.
3. Targeted walk-through of students' workplaces in order to provide practical assistance in mastering drilling, countersinking, and countersinking techniques.
4. Providing practical assistance in determining the quality of the completed task.

3. Cleaning workplaces.

1. Students clean workplaces, hand over tools and completed work.

4. Final briefing. 10 min

Summing up students' work during the lesson.

1. Celebrate the work of the best students.
2. Analysis of mistakes made and ways to eliminate them.
3. Answer students' questions.
4. Submit grades to the journal.

5. Homework assignment.

Familiarization with the material of the next lesson, repeat the topic “Drilling, countersinking, countersinking and reaming holes.”. Textbook "Plumbing" author Skakun V.A.

Master of Industrial Training ______ Ignatenko M.V.

2. BASICS OF FITTING TECHNOLOGY

2.1. technological process

Technological process - This is a part of the production process directly related to changing the shape, size or physical properties of materials or semi-finished products to obtain a product of the required configuration and quality. The technological process is also defined as a part of the production process that contains actions to change and subsequently determine the state of the item of production.

The technological process consists of operations.

Operation - This is a part of the technological process performed by a mechanic at one workplace with or without the use of mechanized or manual tools, mechanisms, devices when processing one part.

Examples of operations: making a groove for lubrication on a sliding bearing, cutting a screw surface on a rod, cutting a thread in a hole, etc.

Elements technological operation are installation, technological transition, auxiliary transition, working stroke, auxiliary stroke, position.

Installation – part of a technological operation performed with constant fastening of the workpiece or assembled assembly unit. For example, drilling one or more holes of different diameters in a part while securing the part unchanged, cutting threads on a rod.

Technological transition – a completed part of an operation, characterized by the constancy of the tool used and the surfaces formed during processing or joined during assembly. For example, drilling a part with a drill of the same diameter or connecting a bushing to a shaft.

Auxiliary transition – part of the operation without changing the geometry of the machined surface or the position of the assembled parts, necessary to perform a technological transition (installation of the workpiece, changing tools, etc.).

Working stroke – the completed part of the operation associated with a single movement of the tool relative to the workpiece, necessary to change the geometry of the part.

Auxiliary move is not associated with a change in the geometry of the part, but is necessary for the implementation of the working stroke.

Position- this is a fixed position occupied by a fixed workpiece or assembled assembly unit together with a device relative to a tool or a stationary piece of equipment to perform a certain part of the operation.

Process map is a technological document containing a description of the process of manufacturing, assembly or repair of a product (including control and movement) for all operations of one type of work performed in one workshop, in technological sequence, indicating data on technological equipment, material and labor standards. It also determines the place of work, the type and dimensions of the material, the main processing surfaces of the part and its installation, working tools and devices, as well as the duration of each operation.

The technological process is developed based on drawing, which for mass and large-scale production must be done in great detail. In case of single production, only a route technological process is often given, listing the operations required for processing or assembly.

The time required to manufacture a product for single and small-scale production is established approximately on the basis of timing or accepted standards, and in large-scale and mass production - on the basis of design and technical standards.

Based is called giving the workpiece or product the required position relative to the selected coordinate system.

Base- this is a surface, a combination of surfaces, an axis or a point belonging to a workpiece or product and used for basing.

Based on their purpose, bases are divided into design, main, auxiliary, technological and measuring.

Design base used to determine the position of a part or assembly unit in a product.

Main base is a design basis that belongs to a given part or assembly unit and is used to determine its position in the product. For example, the main bases of a shaft assembled with bearings are its support journals and a thrust collar or flange.

Auxiliary base- this is a design base that belongs to a given part or assembly unit and is used to determine the position of the product attached to it. For example, when connecting a shaft to a flanged bushing, the auxiliary base may be the shaft diameter, its shoulder and key.

Technological base is a surface, a combination of surfaces or an axis used to determine the position of a workpiece or product during the manufacturing or repair process. For example, the plane of the base of the part and two base holes.

Measuring base used to determine the relative position of a workpiece or product and measuring instruments.

2.2. Universal measuring tool

Rice. 1. Universal measuring instruments: a – measuring metal ruler; b - caliper; c – normal calipers; d – normal bore gauge; d – depth gauge; e – universal goniometer; g – flat square 90"

TO universal measuring instruments for dimensional control used in plumbing, include a folding measuring metal ruler or metal tape measure, a universal caliper, a normal caliper for external measurements, a normal inside gauge for measuring diameter, a simple vernier depth gauge, a universal protractor, a 90° square, and also compasses (Fig. 1).

TO simple special tools to control dimensions used in plumbing, include an angular ruler with a two-sided bevel, a rectangular ruler, a threaded template, a probe, a single-sided assembly plug, a double-sided limit plug, a single-sided limit bracket and a double-sided limit clamp (Fig. 2).

Universal caliper is a measuring tool used for internal and external measurements of length, diameter and depth. It consists of a guide rod made integral with the jaw, which has two supporting surfaces (lower - for external and upper - for internal measurements), a slider, which is integral with the lower movable jaw for external measurements and the upper movable jaw - for internal measurements, clamping frame and retractable depth gauge rod. The guide rod has millimeter markings.

Rice. 2. Simple special tools for controlling dimensions: a – an angular ruler with a double-sided bevel; b – rectangular ruler; in - threaded template; g – probe; d – single-sided prefabricated plug; e – prefabricated double-sided limit plug; g – one-sided limit bracket; h – double-sided limit bracket

The vernier divisions are given on the lower part of the slide. Single-sided and double-sided calipers differ from universal calipers in design. The measuring range of calipers of different sizes is from 0 to 2000 mm.

Vernier- these are the divisions marked on the bottom of the caliper slide.

When counting using a vernier, to the number of whole bar divisions located below the zero of the vernier scale, you should add the number of tenths or hundredths of a millimeter, which corresponds to the number of intervals on the vernier scale to the stroke of this scale, which coincides with one of the strokes of the bar scale. Depending on the graduation of the vernier, a caliper can measure dimensions with an accuracy of 0.1, 0.05 or 0.02 mm.

A caliper with a measurement accuracy of up to 0.1 mm has a vernier with ten divisions over a length of 9 mm, i.e. the distance between the divisions of the vernier is 0.9 mm.

A caliper with a measurement accuracy of up to 0.05 mm has a vernier with twenty divisions on a length of 19 mm, i.e. the distance between the divisions of the vernier is 0.95 mm.

A caliper with a measurement accuracy of up to 0.02 mm has a vernier with fifty divisions over a length of 49 mm, i.e. the distance between divisions is 0.98 mm.

Calipers is a measuring tool used in plumbing to take and transfer the dimensions of a part to scale. The following types of calipers and bore gauges are distinguished: normal for external or internal measurements; spring for external or internal measurements.

The caliper may have a scale for internal measurements.

Compass used for drawing circles, curved lines, or for sequentially transferring the position of points on a line when marking parts. There are spring compasses and arc-mounted compasses.

Angle pattern called square, serves to check or draw angles on the plane of the workpiece. Squares can be flat (regular and patterned), as well as flat with a wide base. A 90° square is a steel template for a right angle. Often, steel angles with an angle of 120°, 45° and 60° are used.

Rectangular and faceted rulers are a simple plumbing aid for checking the flatness or straightness of a surface.

Rectangular rulers include solid rectangular rulers with a wide working surface of an I-section and bridge rulers with a wide working surface. Faceted rulers come with a double-sided bevel, triangular, and tetrahedral. Faceted rulers are made with high precision.

TO templates, which a mechanic often uses include squares, thread templates, feeler gauges, and templates for shaped surfaces.

2.3. Measuring tools and devices for precise measurements

TO tools and devices for precise measurements These include single- or double-sided calipers, standard and angular tiles, micrometers for external measurements, internal micrometric gauges, micrometric depth gauges, indicators, profilometers, projectors, measuring microscopes, measuring machines, as well as various types of pneumatic and electrical instruments and auxiliary devices.

Measuring indicators designed for comparative measurements by determining deviations from a given size. In combination with appropriate devices, indicators can be used for direct measurements.

Measuring indicators, which are mechanical pointer instruments, are widely used to measure diameters, lengths, to check geometric shape, concentricity, ovality, straightness, flatness, etc. In addition, indicators are often used as a component of instruments and devices for automatic control and sorting . The indicator scale division is usually 0.01 mm, in some cases – 0.002 mm. A variety of measuring indicators are minimeters and microcators.

Measuring devices Designed for measuring large size products.

Measuring Projectors – These are devices belonging to the optical group, based on the use of the method of non-contact measurements, i.e., measuring the dimensions not of the object itself, but of its image reproduced on the screen at multiple magnification.

Measuring microscopes, like projectors, belong to the group of optical devices that use a non-contact measurement method. They differ from projectors in that observation and measurement are made not on an image of the object projected on a screen, but on a magnified image of the object viewed through the eyepiece of the microscope. A measuring microscope is used to measure lengths, angles and profiles of various products (threads, teeth, gears, etc.).

Rice. 3. Auxiliary measuring devices: a – measurement plate; b – measuring ruler; c – prism; d – measuring pin; d – sinus bar; e – level; g – measuring stand; z-wedges for measuring holes

TO auxiliary measuring devices include: plates, rulers, prisms, measuring pins, sine rulers, levels, measuring stands and wedges for measuring holes (Fig. 3).

All measuring instruments They are distinguished by high precision execution and require careful care. Providing appropriate conditions of use and storage is a guarantee of their longevity and accuracy. Improper handling leads to premature wear and tear, inability to operate, and even damage to measuring instruments.

When using measuring instruments and instruments, mechanical damage, sudden temperature changes, magnetization, and corrosion are unacceptable.

Necessary requirements for the operation of measuring instruments and instruments are cleanliness, qualified maintenance and, above all, good knowledge of the designs and operating conditions of measuring instruments.

2.4. Metalworking tools, devices and machines

TO locksmith tools include: chisel, cross-meisel, groover, punch, metalworking hammers, drifts, center punch, files, needle files, flat wrenches, universal wrench, socket wrench, overhead wrench, lever wrench for pipes, hook for pipes, chain pipe wrench, various types pliers, pliers, round-nose pliers, hand drills and bench drills, drills, reamers, metalworking taps, dies, metalworking hand vices, screwdrivers, clamps, grips, plate for bending pipes, pipe cutter, hand shears for sheet metal, mandrel with blade for cutting material, wrenches and mandrels for dies, scrapers and tools for inducing decorative patterns, a plate for lapping and lapping, soldering irons, a blowtorch, a pneumatic hammer, a bearing puller, a marking plate, marking tool and screw clamps.

To the main machines, auxiliary equipment and devices used in metalworking work include: turning, milling, planing, drilling, grinding machines, a screw press, a forge with an anvil and a set of forging tools, equipment and tools for soldering, mechanical riveting and heat treatment, manual hoist, table vices, containers for finished products, parts and waste, as well as cleaning materials.

Auxiliary locksmith tools and auxiliary materials are: a hand brush, a metal brush for cleaning files, a marking tool, cleaning materials, chalk, linings on the jaws of a vice, wooden blocks, oils and lubricants, steel markers - digital and alphabetic, a rasp for wood, a mechanic's knife, wooden hammer, rubber hammer, emery cloth, brushes, spoon for melting tin, crucible for melting low-melting alloys of non-ferrous metals, oil and insulating tape, red lead, paints.

Bench workbenches can be of different designs, single and double, permanent and mobile. They can be made of wood or metal; Combined workbenches are also made - from wood and metal. The bench slab is always made of hard wood. At the bottom of the table (under the stove) there is a drawer for tools. Depending on the design of the table, there is a cabinet with shelves on the right (or left) side of the drawer.

A single bench workbench usually has the following dimensions: length 1200 mm, width 800 mm, height 800–900 mm.

Multi-place workbenches (Fig. 4) are installed in large metalwork areas or in metalwork shops. The length of a two-seater table is 3000–3200 mm. The distance between the axes of the vice on two- or multi-place workbenches is 1250–1500 mm.

If the metalworking area does not have natural overhead lighting, the metalworking bench should be installed near the windows so that natural light (through the windows) falls directly or at an angle to the left side of the work area.

Rice. 4. Double bench

Bench vice According to their design, they are divided into parallel with a movable rear or front cheek and chair (Fig. 5).

Rice. 5. Bench vice: a – parallel; b – chair

The group of parallel bench vices includes stationary, rotary, mobile and portable vices. Hand bench vices belong to the group of chair vices. Parallel bench vices differ from chair vices primarily relative position cheeks: in a parallel bench vice, the cheeks diverge parallel and cover the entire surface of the object; The cheeks of a chair vice diverge at an angle, and the object is secured only by the lower surface of the cheeks.

Chair vice They are made from steel forgings, making them resistant to impact. They are used in blacksmithing, less often in metalworking. Bench parallel vices are made of cast iron, so they are not resistant to impacts. Replaceable grooved cheek jaws are made of steel and hardened.

Parallel vice are used mainly for metalwork and are used to perform operations related to manual processing of metal with files, saws, chisels or other tools without significant effort and impact. They are also used in cases where the object being processed must be securely fastened without damaging the clamped surface. This is ensured by clamping over the entire surface of the cheeks and the use of replaceable pads made of soft metal.

A parallel vice consists of the following parts: fixed and movable jaws, base, threaded bushing, screw. The fixed jaw of a fixed vice is integral with the base. There are holes in the base for attaching the vice to the table. The fixed cheek has a bushing with a thread cut inside. A screw having a rectangular or trapezoidal thread passes through a smooth hole in the movable cheek and is screwed into the threaded sleeve of the fixed cheeks. The thickened cylindrical part of the screw has a hole into which the handle is inserted. By screwing in or out the screw, you can move or move apart the jaws of the vice.

A chair vice consists of a fixed and movable jaw, a bracket and a holder used to attach the vice to the table, a bushing with an internal thread, a screw ending in a ball head, and a handle.

The size of the vice is determined by the width of the jaws, cheeks, the greatest distance by which they can diverge, as well as the weight of the vice.

Bench parallel stationary vices have jaw widths ranging from 60–140 mm, the distance at which the jaws diverge is from 45 to 180 mm, and weight is from 3 to 40 kg.

Side pads made of soft metals (copper, aluminum, lead), wood, rubber, artificial and similar materials differ significantly in hardness from the materials of the objects being processed. They protect the surfaces of these objects from damage or change in shape. Side pads are used only for the jaws of parallel vices.

Screw clamp (clamp)- this is auxiliary locksmith's jig, made of steel. The design of clamps varies depending on their purpose. The parts being processed or assembled are clamped using a screw (Fig. 6). Depending on the nature of the operations (processing, assembly), clamps act as either the main clamp or an additional one when processing a part in a vice. Used for small plumbing work.

Wrenches are used to tighten and unscrew nuts and bolts, as well as to hold the bolt when tightening the nuts. There are two types of keys: non-adjustable and adjustable universal.

Rice. 6. Screw locksmith clamps

Non-adjustable keys have a constant size of the throat for the hexagon of a nut or bolt, while universal adjustable wrenches have a key opening that can be changed within certain limits.

Non-adjustable keys are divided into flat single-sided and double-sided (Fig. 7, A And b), overhead one-sided straight and double-sided curved (Fig. 7, V And G), straight and curved end ones (Fig. 7, d And e), as well as hook ones (Fig. 7, and).

Universal wrenches are divided into adjustable wrenches with a head (Fig. 7, h, i), lever (Fig. 7, To), as well as special ones. The group of special wrenches includes ratchet wrenches for nuts, crank wrenches, wrenches for hex or square socket bolts, pipe wrenches, hook wrenches, lever wrenches, chain wrenches, and socket wrenches with interchangeable heads.

Rice. 7. Wrenches

Pliers are used for auxiliary plumbing work. They can bend thin metal materials, as well as hold parts during processing and assembly, and unscrew and screw small nuts. Depending on the purpose and design, the following types of pliers are distinguished: regular pliers (Fig. 8, A), combined flat teeth, round teeth (Fig. 8, b), adjustable straight and curved (Fig. 8, V) pliers, flat and end-nose pliers (nippers), hinged pliers. The group of pliers also includes universal pipe pliers and nail pliers (Fig. 8, G).

Rice. 8. Pliers

Puller – this is a metalworking tool for removing from shafts gear wheels, couplings, pulleys, bearings, levers, etc. A bearing puller consists of two or three clamps (cheeks) and a clip connecting the arms of the clamps, bushings with internal threads, as well as a screw with a hex or square head or handle.

Mechanic's manual jaw hoist refers to plumbing support equipment and is used for lifting and moving heavy parts or materials. The direction of movement can be arbitrary. Hoists are also used for repair and assembly work. Loading capacity of hoists is up to 1.5 tons.

On planer rough processing of flat surfaces of products is carried out in order to reduce to a minimum the manual processing of these surfaces with a file. The cross-planing machine consists of a cast frame, a table and a slide. The drive mechanisms are located in the frame. The slider, located in the upper part of the frame, is driven by a special mechanism into reciprocating motion along the guides of the frame (working and idling). At the end of the slide there is a rotating support head with a holder for the planing cutter. On the vertical guides of the frame, a machine table is mounted on a bracket, which is driven by a lead screw. A parallel vice or clamping device is mounted on the table to clamp the workpieces.

Auxiliary tools and materials depending on the needs of the technological process and production conditions, they have different purposes. They are used to clean the surfaces of objects or tools for their preservation, lubrication, painting, etc. With the help of auxiliary materials, you can give the product an aesthetic, pleasant appearance. An auxiliary tool can be used when processing a product, disassembling or assembling it, and also have another purpose depending on the need and nature of the operations performed.

2.5. Marking

Marking is the operation of applying lines and dots to a workpiece intended for processing. Lines and dots indicate processing boundaries.

There are two types of markings: flat and spatial. The markup is called flat, when lines and points are drawn on a plane, spatial – when marking lines and points are applied to a geometric body of any configuration.

Spatial markings can be made on a marking plate using a marking box, prisms and squares. When marking in space, prisms are used to rotate the workpiece being marked.

For flat and spatial marking, a drawing of the part and a workpiece for it, a marking plate, a marking tool and universal marking devices, a measuring tool and auxiliary materials are required.

TO marking tool include: a scriber (with one point, with a ring, double-sided with a curved end), a marker (several types), a marking compass, punches (regular, automatic for a stencil, for a circle), calipers with a conical mandrel, a hammer, a center compass, a rectangle, marker with a prism.

TO marking devices include: a marking plate, a marking box, marking squares and bars, a stand, a thicknesser with a scriber, a thicknesser with a moving scale, a centering device, a dividing head and a universal marking grip, a rotating magnetic plate, double clamps, adjustable wedges, prisms, screw supports.

Measuring tools for marking are: a ruler with divisions, a thickness gauge, a thickness gauge with a moving scale, a caliper, a square, a protractor, a caliper, a level, a control ruler for surfaces, a feeler gauge and standard tiles.

TO auxiliary materials for marking include: chalk, White paint(a mixture of chalk diluted in water with linseed oil and the addition of a composition that prevents the oil from drying out), red paint (a mixture of shellac with alcohol with the addition of dye), lubricant, washing and etching materials, wooden blocks and slats, small tin containers for paints and a brush.

Simple marking and measuring instruments tools used in plumbing work are: a hammer, a scriber, a marker, an ordinary center punch, a square, a compass, a marking plate, a graduated ruler, a vernier caliper and a caliper.

Planar or spatial marking of the part is carried out on the basis of the drawing.

Before marking, the workpiece must undergo mandatory preparation, which includes the following operations: cleaning the part from dirt and corrosion (do not do it on a marking plate); degreasing the part (do not do it on a marking plate); inspection of the part in order to detect defects (cracks, cavities, bends); checking overall dimensions and processing allowances; determination of the marking base; covering with white paint the surfaces to be marked and lines and dots applied to them; determination of the axis of symmetry.

If a hole is taken as a marking base, then a wooden plug should be inserted into it.

Marking base- this is a specific point, axis of symmetry or plane from which, as a rule, all dimensions on a part are measured.

By capping called the operation of applying small dots-indentations on the surface of a part. They define the centerlines and hole centers required for machining, certain straight or curved lines on the product. The purpose of marking is to mark persistent and noticeable marks on the part that define the base, processing boundaries or drilling location. The punching operation is performed using a scriber, a center punch and a hammer.

Markup using a template used in the manufacture of a significant number of identical parts. A template made of tin 0.5–2 mm thick (sometimes stiffened with a corner or wooden slats), is applied to the flat surface of the part and traced along the contour with a scriber. The accuracy of the applied contour on the part depends on the degree of accuracy of the template, the symmetry of the scriber's tip, as well as on the method of advancing the scriber's tip (the tip must move perpendicular to the surface of the part). The template is a mirror image of the configuration of parts, lines and points that must be applied to the surface of the part.

The accuracy of marking (the accuracy of transferring dimensions from the drawing to the part) depends on the degree of accuracy of the marking plate, auxiliary devices (squares and marking boxes), measuring instruments, the tool used to transfer dimensions, on the degree of accuracy of the marking method, as well as on the qualifications of the marker. The marking accuracy is usually from 0.5 to 0.08 mm; when using standard tiles - from 0.05 to 0.02 mm.

When marking, you should handle sharp scribers with care. To protect the worker’s hands before marking, it is necessary to put a cork, wooden or plastic cover on the tip of the scriber.

To install heavy parts on the marking plate, you should use hoists, hoists or cranes.

Spilled oil or other liquid on the floor or marker board may cause an accident.

2.6. Chopping, cutting, trimming and profiling parts from sheet material

A bench chisel (Fig. 9) is a tool made of tool carbon steel U7A or U8A with a rectangular or rounded profile, one end of which has a wedge shape. Chisel dimensions: length 100–200 mm, thickness 8–20 mm, width 12–30 mm. A metalworking chisel is used for chopping or removing a layer of metal when precision processing is not required. It can also be used to cut, trim and trim material.

Rice. 9. Bench chisel

Depending on the type of material being cut or trimmed, the sharpening angle of the chisel is: 60° for steel, 70° for cast iron and bronze, 45° for copper and brass, 35° for zinc and aluminum.

The material to be cut (tin plate, strip iron, steel strip, profile, rod) should be placed on a steel plate or anvil so that its entire surface is adjacent to the surface of the plate or anvil. The material from which the workpiece needs to be cut can be secured in a vice. If the metal is longer than the plate or anvil, its overhanging end should be supported by suitable supports.

A sheet or piece of tin with the outline of the element marked on it is placed on a steel plate to cut the tin. The tip of the chisel is placed at a distance of 1–2 mm from the marked line. By hitting a chisel with a hammer, the tin is cut. By moving the chisel along the contour and simultaneously hitting it with a hammer, they cut out the shaped element along the contour and separate it from the sheet of tin.

Cutting an element from a thick one sheet material This is done first on one side of the sheet, then it is turned over to the other side and cut out completely (by moving the chisel along the resulting mark from the tip of the chisel). The cut element along the contour is processed with a hand file.

Before marking, bent or dented sheet metal should be straightened on the plate with a rubber or wooden hammer. Before laying the sheet on the slab during straightening, marking and cutting, the slab should be thoroughly cleaned and wiped. The tin must adhere to the slab with its entire surface. Do not use a dull or chipped chisel or a chipped or chipped hammer.

A chisel is used to cut material in cases where it is difficult or impossible to use scissors or a saw due to the complexity of the required configuration of the part, when the necessary scissors are not available (generally or at the moment), when the material being cut is too hard.

When cutting viscous materials (thick tin or strip iron), in order to protect the chisel from jamming, the cutting part of the chisel should be lubricated with oil or water and soap, which reduces friction and makes it possible to obtain a smooth cut surface.

Circumcision- This is the removal of the edge of the material using a chisel, as well as the removal of beads and sprues on the surface of the castings.

Kreutzmeisel- This is a metalworking tool that is similar to a chisel, but has a narrow or shaped (groove) cutting part. It is used for cutting rectangular or shaped grooves. Made from tool carbon steel U7A or U8A. Crossmeisel dimensions: length 150–200 mm, width 12–25 mm, thickness 8–16 mm; groover dimensions: length 80-350 mm, width 6-25 mm, thickness 6-16 mm.

There are several types of crossbars: rectangular, semicircular and special (Fig. 10).

Cutting is the process of making grooves, recesses, and also auxiliary grooves using a crossmeisel when cutting a large surface.

Rice. 10. Kreutzmeiseli: a – rectangular; b – semicircular (grooved)

A chisel is used for cutting, and a cross-section is used for cutting.

The chisel is made of carbon tool steel U7A or U8A with a carbon content in the range of 0.65–0.74% (U7A steel) and 0.75–0.84% ​​(U8A steel). After heating one end of the chisel blank to a temperature of 900–350 °C, it is forged, giving it the shape of a point.

After forging (obtaining a wedge), this part of the workpiece is pre-sharpened and heated again to the hardening temperature (770–790 °C; flame color - cherry), after which the tip is lowered into water to a depth of 15 mm for two seconds in order to harden it. After hardening, the workpiece, while still heated, is cleaned of scale on a steel plate or with a file, while simultaneously observing the color of the coating that gradually appears on the tip during cooling. Tempering is carried out at a temperature of 200–290 °C (the color of the coating ranges from light straw to violet-blue). The chisel head is tempered depending on the type of steel at a temperature of 300–330 °C (the color of the coating ranges from dark blue to gray).

The second tempering method is based on complete cooling of the tool after hardening, cleaning it and reheating it to the appropriate tempering temperature (temperature and coating colors are given above), upon reaching which the tool quickly cools. After tempering, the cutting part is sharpened. Hardness of the working part of chisels and crossbars at a length of 0.3–0.5 cone part H.R.C. 52–57, impact part at a length of 15–25 mm – H.R.C. 32–40 (methods for determining and designating the hardness of metals are discussed in paragraph 4.3).

For mechanical cutting, a manual pneumatic hammer with a chisel inserted into it is used.

Pneumatic hammer driven by compressed air. Pneumatic hammers are also used for riveting and construction work. They provide (depending on design) from 750 to 3000 beats per minute. They are used both indoors and in open areas during installation and construction work.

The heads of chisels and crosspieces have beveled, ground surfaces rounded at the end. If the tip becomes dull or damaged, the cutting part of the chisel should be sharpened to the appropriate angle. After work, the tool must be cleaned of dirt and wiped with a cleaning cloth soaked in oil.

If safety requirements are not followed when cutting, cutting and trimming, a mechanic most often receives injuries to his hands or face from fragments of the materials or tools being processed. When working with a chisel or cross-cutting tool, wear safety glasses and gloves. Workplace A mechanic working with a chisel must be protected by a protective net.

2.7. Manual and mechanical straightening and bending of metal

For straightening shaped, sheet and strip metal, various types of hammers, plates, anvils, rolls (for straightening tin), manual screw presses, hydraulic presses, roll devices and gates are used.

Bending of metal depending on its thickness, configuration or diameter is done with a hammer using metal tongs or blacksmith's tongs on a straightening plate, in a vice or in molds or on an anvil. You can also bend metal in various bending fixtures, bending machines, press brake dies, and other equipment.

A hammer is a percussion instrument consisting of a metal head, a handle and a wedge (Fig. eleven).

Rice. 11. Plumber's hammer: a – metal head; b – handle; c – wedge

The hammer is widely used in performing various plumbing operations; This is one of the main tools when performing locksmith work.

The metal part consists of the following elements: a wedge-shaped part, a slightly rounded butt (impact part) and a hole. The hammer handle is made of hard wood with a cross-section and length depending on the size of the hole in the hammer and its weight. After placing the hammer on the handle, a wooden or metal wedge is driven into it to protect the hammer from falling off the handle.

Hammers come with a round and square head. Bench hammers are made from tool carbon steel U7 or U8 (Table 1). The working part of the hammers is hardened to hardness H.R.C. 49–56.

Table 1 Weight and dimensions of locksmith hammers

Straightening is the operation of returning crooked or bent metal products to their original straight or other shape. Straightening is done hot or cold manually, as well as using devices or machines.

Most often, wire, hot-rolled or cold-drawn rods, strip and sheet metal are straightened. Sectional metal (angles, channels, T-beams, I-beams and rails) undergoes editing less frequently.

A material or product made of non-ferrous metals should be adjusted taking into account its physical and mechanical properties with a hammer made of the appropriate metal. Hammers made of the following non-ferrous metals are used: copper, lead, aluminum or brass, as well as wooden and rubber hammers.

Flexible called the operation of giving metal a certain configuration without changing its cross-section and processing the metal by cutting. Bending is done cold or hot manually or using devices and machines. Bending can be done in a vice or on an anvil. Bending metal and shaping it can be facilitated by the use of templates, core molds, bending dies and fixtures. Bending a large number of metal rods to give them a specific shape is possible only in dies and bending equipment specially designed and manufactured for this purpose.

Rice. 12. Pipe bending device

The wire bends under a certain radius or along a circle with round teeth, and when bending under small angle– pliers;

For complex bending, circle pliers and pliers can be used simultaneously. In some cases, a vice is used when bending wire.

Pipe bending can be done hot or cold using special templates or rollers using bending devices (Fig. 12) or pipe bending machines.

Thick-walled pipes with a diameter of no more than 25 mm and a bending radius of more than 30 mm can be bent in a cold state without filling them with dry fine sand, lead, rosin and without inserting a coil spring into them. Pipes of large diameters (depending on the wall thickness and the grade of metal from which the pipe is made) are bent, as a rule, by heating the bending point and filling the pipe with the appropriate material. In this case, the ends of the pipe are plugged with plugs, which reduces the possibility of its breakage or flattening during bending. Pipes with a seam should be bent in such a position that the bending force is applied in a plane perpendicular to the seam.

Pipe flaring- this is a diametric expansion of the pipe ends outward in order to obtain a tight and durable press connection of the pipe ends with the holes into which they are inserted. It is used in the manufacture of boilers, tanks, etc. Flaring is performed mainly with manual flaring roller tools or conical mandrels.

Spring- this is a part that, under the influence of external forces, elastically deforms, and after the cessation of the action of these forces returns to its original state. Springs are used in various machines, devices, machines and equipment. Springs are classified according to their shape, operating conditions, type of load, type of tension, etc. Based on their shape, springs are divided into flat, helical (cylindrical, shaped, telescopic) and conical. Based on the type of loading, they are divided into tension, torsion and compression springs. Springs are made with right or left winding, spiral disc, bent, flat, figured and ring (Fig. 13).

The spring must support parts or assembly units of machines in a certain position, eliminate or calm vibrations, and also perceive the energy of a part or machine assembly in motion, make it possible to elastically suspend machine parts or counteract a certain force. The spring also serves as an indicator of a certain force.

Rice. 13. Springs: a – flat; b – cylindrical screw; c – spiral; g – disc-shaped; d – bent; e – ring

Springs are made of spring or spring steel. It can be high-carbon steel or alloyed spring and spring steel with the addition of manganese, chromium, tungsten, vanadium, and silicon. The chemical composition of spring and spring steel, heat treatment conditions, as well as mechanical properties are determined by the relevant GOST and technical specifications.

Rice. 14. Winding a coil spring in a vice manually

Springs are made by hand or by machine. One of the simplest manual methods is to make springs in a vice (Fig. 14) using a round rod with a handle with a diameter slightly smaller than the internal diameter of the spring, and special wooden cheeks inserted between the jaws of the vice cheeks. Helical springs can also be wound on drilling, lathe or special winding machines.

The length of round wire required to wind a helical spring is determined by the formula:

L = ?D cp n,

Where L– total length of the wire;

D cp is the average diameter of the spring coils (equal to the internal diameter plus the wire diameter); n– number of turns.

Rubber spring coupling- This is a type of spring. Rubber connecting spring parts are used in various machines, mechanisms and equipment for connecting shafts and a number of other parts operating under dynamic loads. They have the ability to receive and store energy, dampen vibrations and are used as flexible and elastic couplings.

Before installing a spring or a rubber connecting spring part, you should first check that the type, characteristics and quality of the spring correspond to the drawing and technical requirements for assembling a machine or mechanism. A spring or rubber connecting spring part that does not meet these requirements or has mechanical damage will not ensure the operability of the machine or mechanism.

When straightening and bending metal, it is necessary to check technical condition tools used, correctly and accurately fix the material on a plate, in a vice or other device. The sleeves of clothing should be buttoned at the wrists, and mittens should be worn on the hands.

2.8. Manual and mechanical cutting and sawing

By cutting is the operation of dividing a material (object) into two separate parts using hand scissors, a chisel or special mechanical shears.

Sawing is the operation of separating a material (object) using a manual or mechanical hacksaw or circular saw.

Rice. 15. Hand scissors for cutting metals

The simplest tools for cutting metal are ordinary hand scissors(Fig. 15), right and left (the upper cutting edge can be located to the right or left of the lower cutting edge).

Scissors can be hand-held or stationary, mounted on a workbench. Mechanical devices and equipment include vibrating shears and machines, lever mechanical shears, and guillotine shears and presses. Cutting of sheet material, especially cutting of shaped parts, is carried out with a gas acetylene-oxygen torch, and in some cases - with a milling machines finger and other special cutters. Cutting of bar material can be done on lathes using cutting tools. Pipe cutting is done with special pipe cutters. For sawing materials, manual and mechanical hacksaws with a permanent or sliding frame, band saws, circular saws and other mechanisms.

Hand scissors are used for cutting tin and iron sheets up to 1 mm thick, as well as for cutting wire. Sheet material up to 5 mm thick is cut with lever shears, and material with a thickness of more than 5 mm is cut with mechanical shears. Before cutting, the cutting edges should be lubricated with oil.

The sharpening angle of the cutting parts of the scissors depends on the nature and brand of the metal and material being cut. The smaller this angle, the easier the cutting edges of the scissors cut into the material, and vice versa. However, at a small sharpening angle, the cutting edges quickly chip. Therefore, in practice, the sharpening angle is chosen within the range of 75–85°. Blunt edges of scissors are sharpened on a grinding machine. The correctness of sharpening and placement between the clams is checked by cutting the paper.

Hand saw consists of a fixed or adjustable frame, handle and hacksaw blade. The canvas is secured in the frame using two steel pins, a bolt and a wing nut. A bolt with a nut serves to tension the canvas in the frame (Fig. 16).

Rice. 16. Hand hacksaws for metal a – adjustable; b – unregulated

Hand saw blade- This is a thin hardened steel strip with a thickness of 0.6 to 0.8 mm, a width of 12–15 mm and a length of 250–300 mm with cut teeth along one or both edges. The hacksaw blade has a thickness of 1.2–2.5 mm, a width of 25–45 mm and a length of 350–600 mm.

The tooth of the blade is characterized by the following angles: for a manual hacksaw blade, the rake angle is 0°, the rear angle is 40–45°, pitch 0.8 mm, tooth set width 1.2–1.5 mm; for hacksaw blades, the rake angle is 0–5°, the clearance angle is 35–40°, the tooth sharpening angle is 50–55°, the tooth pitch is 2–6 mm. The teeth are wavy and set apart. Soft metals and artificial materials are cut with a hacksaw with large pitch teeth, hard and thin materials– chalk saw blades are made of high-carbon tool steel U10, U12, U10A, U12A, for especially critical work – from steel R9, Kh6VF, Kh12F1, tungsten and chromium. After cutting the teeth, the blade is hardened completely or partially (only teeth) to hardness H.R.C. 60–61. The working length of the blade is about 2/3 of its length. Each tooth of the hacksaw blade is a planing cutter (Fig. 17).

Rice. 17. Blades with cut teeth: a – two-sided; b – one-sided

Before sawing or cutting the material, the material should be prepared, marked with a scriber or marked with a mark.

The misalignment of the hacksaw during the sawing process causes significant bending stresses on the blade, which can cause cracks or breakage of the blade.

If one or more teeth on the blade break, you should interrupt sawing, remove the blade from the frame and grind off the chipped teeth. After this, you can continue to use the canvas.

Sawing large-diameter pipes must be done with a gradual rotation of the pipe: otherwise the teeth may break. A thin pipe should be secured in a vice or radius crimping device with a slight clamping force, otherwise the pipe may collapse. For sawing pipes, use a blade with intact, sharp teeth of a small pitch. A new blade should not be inserted into the cutting area where the old blade has cracked or its teeth have crumbled.

If the cutting line goes at an angle to the metal surface, you should interrupt sawing on this side and start on the other. To avoid the blade sliding on the material, you need to make the initial cut with a triangular file.

Hard materials are usually sawed using a mechanical frame saw, band saw or circular saw. Manual sawing of these materials is very labor-intensive, and sometimes simply impossible. Mechanical sawing produces an even cut.

Rice. 18. Knife pipe cutters (roller): a – three-knife; b – with one knife and two rollers

Pipe cutter – This is a tool for cutting pipes (Fig. 18). Pipe cutters come in different types: one-, two- and three-blade, as well as chain.

In a pipe cutter, the role of the cutting part is played by a roller with sharpened edges. A three-knife pipe cutter consists of a jaw in which there are two roller knives, a holder in which one roller is installed, a handle and a lever. A pipe cutter is placed on the pipe secured in a vice or gripping device and, using the handle, tightened until it stops. The oscillatory or rotational movement of the lever and the gradual approach of the roller knives cuts the pipe. A uniform and clean pipe cutting line can be achieved using a chain pipe cutter.

For safety reasons, when cutting and sawing material, you should check the tool, correctly and securely fasten the material in a vice or fixture, and also correctly and firmly seat the handle of the frame saw. Dangerous places near mechanical shears are covered with a casing or shields. Mechanical shears are maintained in accordance with the operating instructions by a specially trained worker.

2.9. Manual and mechanical filing

Filing – This is the process of removing stock using files, needle files or rasps. It is based on manual or mechanical removal of a thin layer of material from the surface being treated. Filing is one of the main and most common operations. It makes it possible to obtain the final dimensions and the required surface roughness of the product.

Filing can be done with files, needle files or rasps. Files are divided into the following types: metalworking files for general purposes, metalworking files for special works, machine, for sharpening tools and for hardness control.

Files are made from high-carbon tool steel U12A, U13A, as well as steel grades P9, P7T, ShKh9, 111X15.

File teeth can be formed by notching, milling, tapping, broaching, and rolling turning. The most common method is cutting. The cut of files for general purpose is double cross, and for files for special work it is double and single. Thanks to the cross notch on the surface being filed, there are no marks from traces of tooth movement. The teeth are cut on the workpieces before they are heat treated. After cutting, the files are hardened to a hardness of at least H.R.C. 54.

When repairing worn files, the surface of the files is tempered and ground before applying the notch. All files must be tested.

Depending on the shape, the following types of files are distinguished (Fig. 19): A– metalworker’s flat, blunt-nosed ones; b– round; V– semicircular, G– square; d– triangular; e– flat pointed noses; and– hacksaws; h– oval; And– lens; To– rhombic; l– semicircular wide; and- rasps, n– for filing machines; O– for soft metals, as well as curved files. The file sizes are given in table. 2.

Rice. 19. Shapes of bench files table 2 Shapes and sizes of files, mm

According to the size and density of the notches, depending on the number of notches per 10 mm of length, the files are divided into basal files No. 0 and 1, personal files No. 2 and 3 and velvet files No. 4 and 5. Brussels file No. 0 has the coarsest notch. With a garnish file length of 100 mm, the number of notches on a length of 10 mm is 14, while velvet file No. 5 has a very fine notch - 56 notches per 10 mm with the same file length (Tables 3–5).

Table 3 The size of the allowance and the accuracy of processing with files of various classes, mm
Table 4Number of notches per 10 mm file length
Table 5Number of auxiliary notches per 10 mm file length

Files come with single and double notches (Fig. 20). A single notch can be inclined in one direction, inclined at intervals, wavy, rasp. When filing soft metal surfaces, files with a single cut are used. Double notching is characterized by the fact that the pitch (the distance between the tops of two adjacent teeth) is not a whole value, which prevents the appearance of grooves on the surface being cut.

Rice. 20. Types of file cuts: a – single with a slope in one direction; b – single inclined with intervals; c – wavy; g – rasp; d – double

The following types of filing are distinguished: flat and curved surfaces; corner surfaces; parallel surfaces; complex and shaped surfaces.

The choice of file depends on the type of material, the type of filing, the size of the layer being removed and the size of the workpiece. For example, when finishing a cube made of steel with an edge length of 30 mm, you need to use a double-cut file No. 5 (velvet) with a length of 160 mm.

The shape of the files is chosen depending on the configuration of the area being treated. Flat files are used for filing flat, curved convex and outer spherical surfaces; square files – for filing square and rectangular holes; triangular - for processing triangular surfaces, for sharpening saws, as well as for filing flat surfaces located at an acute angle; hacksaws - for filing the edges of sharp corners, as well as for making narrow grooves; rhombic - for processing very complex contours of products; round – for making semicircular and round holes; oval – for filing oval holes; semicircular and lens - for processing curved and concave surfaces.

In table Table 6 shows the roughness classes and the corresponding heights of surface microroughnesses obtained with different types of metalworking.

Table 6 Surface roughness obtained by different types of metalworking

Correct and reliable fastening of the material in a vice or device during filing ensures accurate processing of the material, minimal worker effort and labor safety.

To avoid damage to the surfaces of non-metallic materials and products secured in a vice, pads should be used. Pads made of soft metals (copper, zinc, lead, aluminum, brass), wood, artificial material, felt or rubber are placed on the jaws of the vice. The product or material is placed between the pads and then secured.

The installation height of the vice when filing should be selected in accordance with the height of the worker. In practice, the installation height of the vice is determined by resting your elbows on the cheeks of the vice (with your hand in a vertical position, your fist should reach the chin of a worker standing straight). If the vice is installed below this position, then spacers are placed, and if the installation height of the vice is high, then the spacers are removed or a stand or ladder is placed under the mechanic’s feet. The person working at the vice should take a position such that the feet are at an angle of 45° to each other, and the left leg should be placed forward at a distance of 25–30 cm from the axis of the right leg. The axis of the left foot in relation to the working axis of the file should be at an angle of about 30°. This situation guarantees productive and safe work mechanic and reduces his fatigue.

Restoring the cutting ability of a file after wear is ensured by removing dull teeth and applying a new notch to the file. Restoration is carried out by annealing the file, grinding off the old notch and making a new one (manually or mechanically), followed by hardening. The file can be restored several times, but each time it becomes thinner and more susceptible to cracks.

Files must be protected from moisture to prevent corrosion; To avoid damage to the cuts, do not throw them or place them on other files, tools or metals. The surface of the files is protected from oil or grease, as well as from dust from the grinding wheels.

A new file should be used on one side first, and after it has become dull, on the other. Personal and velvet files should not be used for filing soft metals (tin, lead, copper, zinc, aluminum, and brass). Sawdust from these metals clogs the grooves of the file and makes it impossible to process the surfaces of other metals.

The file should be cleaned with a steel brush during and after use. After finishing work, it is put away in a drawer or cabinet.

Please note Special attention on the condition of the handle and its correct attachment to the file (the handle is placed along the axis of the file). When attaching the handle, do not lift the file upward. Files without a handle should not be used. You need to be especially careful when working with small files. The end of a long file should not be held with your fingers. The material to be filed must be secured correctly and firmly.

2.10. Drilling and reaming. Drilling machines

Drilling is the making of a round hole in a product or material using a special cutting tool - a drill, which during the drilling process simultaneously has a rotational and translational movement along the axis of the hole being drilled. Drilling is used primarily when making holes in parts that are connected during assembly.

When working on drilling machine the drill performs rotational and translational motion; in this case, the workpiece is motionless. Processing of parts on a lathe, automatic machine or turret machine is performed when the part rotates, and the tool makes only translational movement.

Depending on the required degree of accuracy, the following types of processing are used: drilling, reaming, countersinking, reaming, boring, countersinking, centering.

The following operations can be performed on drilling machines: drilling, reaming a previously drilled hole to a larger diameter, countersinking, reaming, facing, countersinking, countersinking, threading.

To perform the drilling operation, drills with a conical or cylindrical shank, conical adapter bushings, wedges for knocking out drills, self-centering drill chucks with two and three jaws, handles for fastening drills in chucks, quick-release chucks, spring chucks with automatic shutdown of the drill, machine vices, boxes are used. , prisms, clamps, squares, hand vices, inclined tables, as well as various types of devices, manual and mechanical drilling machines and drills.

There are drilling machines with manual and mechanical drive. Hand-operated drilling machines include: rotary hammers, drills, ratchet drills, and hand-held drilling benches. Manual drilling machines with a mechanical drive include electric and pneumatic drills, which, when using special shanks, allow you to drill holes in hard-to-reach places.

Mechanically driven drilling machines include vertical drilling machines, radial drilling machines, horizontal boring machines and special drilling machines. Vertical drilling machines may have devices for using multi-spindle heads. Special drilling machines can be modular, multi-position and multi-spindle.

A vertical drilling machine differs from other drilling machines in that it has a frame with vertical guides along which the machine table can move. In addition, it has a feed mechanism, a pump for supplying coolant, as well as gearboxes for obtaining different rotation speeds of the drilling spindle of the machine.

On vertical drilling machines (depending on the type) you can drill holes with drills with a diameter of up to 75 mm, on bench drilling machines - with drills with a diameter of up to 15 mm, on tabletop drilling machines - with drills with a diameter of up to 6 mm. Manual electric drills(depending on the type) you can drill holes with a diameter of up to 25 mm, with hand-held pneumatic drilling machines - drills with a diameter of up to 6 mm.

Drilling ratchets are used for drilling holes in hard-to-reach places in steel structures. The manual drive, provided by the oscillatory movement of the ratchet lever, creates rotation of the drill and its feed along the axis of the hole.

The disadvantage of drilling with a ratchet is the low productivity and high labor intensity of the process.

Drill is a cutting tool used to make cylindrical holes (Fig. 21).

Rice. 21. Drill: a – spiral; b – feathers

By constructive design The cutting part of the drill is divided into feather, with straight flutes, spiral with helical flutes, for deep drilling, centering and special.

Twist drills depending on their execution, they are divided into twisted, milled, cast (for large diameters), with plates made of metal carbide alloys and welded.

Drills are made from tool carbon steel U10A, U12A, alloy steel 9ХС or from high-speed steel R18, R9, REM. Drills lined with tungsten and titanium carbide alloy plates are often used.

A twist drill is used to make holes that have high accuracy requirements, holes intended for further processing by reaming, boring or pulling, holes for threading (Table 7).

Table 7 Hole machining accuracy th

A twist drill consists of a shank and a working part, which is divided into a guide and cutting parts. There is a neck between the guide part and the shank.

Shank- this is a part of a drill of a cylindrical or conical shape (wood drills have a tetrahedral conical shank), which serves to secure the drill in a conical shape in conical adapter sleeves with a Morse taper, and in a cylindrical shape in a two- or three-jaw drill chuck. The end bushings and drill chuck are secured in the spindle hole. Tapered shanks end with a foot, which serves to knock the drill out of the spindle or tapered adapter sleeve. The cylindrical shank ends with a leash. Drill bits with square shanks are most often used to drill holes with drill ratchets or hand cranks. Drills with a cylindrical shank usually have small diameters (up to 20–30 mm).

The working part of the drill consists of a guide and cutting parts.

Drill guide- this is the part located between the neck and the cutting part. It serves to guide the drill along the axis of the hole. The guide part has helical grooves for removing chips and a drill rod. There is a ribbon on the outer screw surface of the drill guide.

Cutting part of twist drill consists of two cutting edges connected by a third edge - the so-called transverse bridge.

Ribbon called a narrow belt along the helical groove, smoothly running down to the shank. The purpose of the tape is to absorb part of the friction of the drill against the walls of the hole that appears as the tool enters the material. The diameter of the drill is measured by the distance between the strips.

The angle of inclination of the helical flute of the drill depends on the type of material being processed (Table 8).

Table 8 Recommended drill point angles

The process of cutting metal with a cutting edge is carried out by cutting it into the metal under the action of rotation of the drill and its axial feed. The angle of the cutting edge is determined by the angle of inclination of the helix and the rear sharpening angle of the drill. The amount of required feed force and cutting force are determined by the size of the rake and back cutting angles and the size of the transverse edge. You can reduce the required feed force when drilling by sharpening the transverse edge (jumper) and choosing the optimal cutting angle for a given material.

If the drill does not drill well, it should be sharpened. Sharpening can be done manually or by machine. Proper sharpening of the drill makes it possible to obtain the necessary angles, extends the service life of the drill, reduces effort, and also makes it possible to obtain correctly made holes.

Selecting the cutting angles required for a given material and sharpening on special sharpening machines for drills ensures that the correct sharpening angles are obtained and the position of the transverse edge in the center of the drill. After sharpening, you can check the sharpening angles using a protractor or a template.

Feather drills(Fig. 21, b) are usually made of carbon tool steel U10A or U12A. These drills have the following elements: a double-sided cutting part with an angle of 116°, a single-sided cutting part with an angle of 90–120°, a guide part with an angle of 100–110°, a conical working part, a neck and a shank.

The double-sided cutting part provides working movement when the drill rotates in both directions. The single-sided cutting part ensures that the drill works in only one direction.

The disadvantage of these drills is the lack of a guide and the diameter changes with each sharpening. Used for small diameter holes that do not require high precision execution.

Feather drills with an extended guide provide better direction and a more accurate hole size, making it possible to obtain the same diameter until the guide is ground off. However, these drills are not very productive.

Before drilling, it is necessary to properly prepare the material (mark and mark the drilling locations), the tool and the drilling machine. After securing and checking the installation of the part on the drilling machine table or in another device, as well as after securing the drill in the machine spindle, begin drilling in accordance with the instructions and labor safety requirements. We must not forget about cooling the drill.

During the drilling process, various defects may occur: drill breakage, chipping of cutting edges, deviation of the drill from the hole axis, etc.

In table 9 indicates the types of defects, the causes of their occurrence, as well as methods of elimination.

Table 9 Drilling defects

A drilling jig (Fig. 22) is a device with a jig plate for processing a large number of identical parts with equally spaced holes without preliminary marking. Drilling jigs can be of different designs. They can be installed on the part and attached directly to the part; they can be a device with a jig plate into which the part is installed and clamped. In this case, in the jig plate there are appropriately located holes with jig bushings inserted into them with a certain diameter of the holes, through which the drill is directed into the part clamped into the drilling device. In some cases, conductor plates have holes without conductor bushings.

Rice. 22. Device with a jig plate for drilling: 1 – drill; 2 – bushing; 3 – conductor plate; 4 – lower part of the conductor; 5 – workpiece; 6– screw with wing nut

When drilling, cooling and the coolants used play an important role. Cutting fluid (coolant) performs three main functions: it is a lubricant to reduce friction between cutting tool, drill, metal of the part and chips, is a cooling medium that intensively removes heat generated in the cutting zone and facilitates the removal of chips from this zone.

Coolants are used for all types of metal cutting. A good coolant does not cause corrosion of tools, fixtures and parts, does not have a harmful effect on human skin, does not have an unpleasant odor and removes heat well. When drilling holes in steel, use an aqueous solution of soap, a 5% solution of E-2 or ET-2 emulsion; when drilling in aluminum - a 5% solution of emulsion E-2, ET-2 or a liquid of the following composition: Industrial oil - 50%, kerosene - 50%. When drilling small holes in cast iron, coolant is not used. When drilling deep holes in cast iron, compressed air or a 1.5% solution of E-2 or ET-2 emulsion is used. When drilling copper and alloys based on it, use a 5% solution of emulsion E-2, ET-2 or Industrial oil.

To obtain holes in metal or parts with a diameter of over 30 mm, double drilling should be used. The first operation is performed with a drill with a diameter of 10–12 mm, the second with a drill of the required diameter (reaming). When drilling with two holes or drilling, reaming and countersinking, cutting forces and operating time are significantly reduced.

You can remove a broken drill from the hole being drilled by turning it in the direction opposite to the spiral of the broken part using pliers (if there is a protruding part of the drill). If the broken drill is inside the material, then the part being drilled is heated together with the drill until reddened, and then gradually cooled. The released drill can be unscrewed with a special device or drilled with another drill.

Center drill called the tool used to perform center holes in the end surfaces of the shafts. There are two types of centering drills: for regular center holes without a safety cone and for center holes with a safety cone (Fig. 23). The normalized angle of a regular center drill is 60°, and the normalized angle of a drill with a safety cone is 60 and 120°.

Rice. 23. Centering drills: a – ordinary without a safety cone; b – with safety cone

On large and heavy shafts, the center recess at the ends is performed in three operations: drilling, countersinking at 60° and countersinking the safety cone at 120°.

Countersinking- this is an increase in the diameter of a previously drilled hole or the creation additional surfaces. For this operation use countersinks, the cutting part of which has a cylindrical, conical, end or shaped surface (Fig. 24).

The purpose of countersinking is to create adequate seats in holes for the heads of rivets, screws or bolts or to align end surfaces.

Rice. 24. Countersinks: a – cylindrical for countersinking through or deep holes; b – conical for chamfering and forming conical recesses; c – end ones for countersinking the end surfaces of bosses (trimming); d – shaped for countersinking shaped surfaces

Countersinks are made of carbon tool steel U10A, U12A, alloy steel 9ХС or high-speed steel R9, R12. They may have soldered cutting inserts made of hard alloys. Shanks of countersinks and bodies of typesetting countersinks are made of steel 45 or 40X.

Countersinks can be solid cylindrical, conical, shaped, welded with a welded shank, solid mounted, prefabricated mounted. Countersinks of small diameters are usually made solid, and those of large diameters are welded or mounted. Conical countersinks have apex angles of 60, 75, 90 and 120°.

Scan is a multi-edge cutting tool used for finishing holes to produce a hole with a high degree of accuracy and a low surface roughness.

Reamers are divided into rough and finishing. The final deployment achieves an accuracy of 2–3 classes (10–7 quality), and with particularly careful execution – 1st class (6–5 quality) with a surface roughness of 7–8 classes of cleanliness (height of microroughnesses 1.25– 0.32 µm).

Reaming gives the final hole size required by the drawing. The diameter of the hole for reaming should be less than the final one by the amount of the reaming allowance (Table 10).

Table 10 Allowance for diameter for reaming after drill, cutter or countersink, mm

The following types of reamers are distinguished: by method of use - manual and machine, by shape - with a cylindrical or conical working part, by processing accuracy - rough and finishing, by design - with a cylindrical shank, with a conical (Morse taper) shank and mounted ones. Attachment reamers can be solid, with inserted knives, or floating. Manual reamers can be solid or expanding. Reamers can have simple and helical teeth. In Fig. 25 presented manual reamers.

Rice. 25. Sweeps: a – conical rough; b – conical intermediate; c – conical finishing; g – cylindrical with straight teeth; d – cylindrical adjustable; e – cylindrical expansion

The number of reamer teeth depends on its diameter and purpose. The number of teeth in manual and machine reamers with straight teeth is most often even (for example, 8, 10, 12, 14). Spiral tooth reamers have left- and right-handed cutting parts.

Expanding and adjustable reamers are used during repair work to ream holes that have different tolerances, as well as to minimally enlarge a completed hole.

The set of conical reamers for Morse taper sockets includes three reamers: rough, intermediate and finishing (conical) reamers.

Boiler reamers are used in boiler work to enlarge holes for rivets.

The reamer has the following elements: a working part, a neck and a shank (conical or cylindrical).

The shanks of manual three-finger reamers are fixed in permanent or adjustable holders.

Reamers have an uneven pitch of the cutting edges: in order to improve the quality of the hole and prevent its faceting, the teeth are located around the circumference at different distances from one another.

Coolant is used to cool the tool, reduce friction, and also increase the service life of the cutting part of the tool. In table Figure 11 shows the compositions of coolant used when drilling holes in various materials.

Table 11Coolant used when reaming holes in different materials

For the manufacture of reamers, carbon tool steels U10A and U12A, alloy tool steels 9ХС, ХВ, ХГСВФ, high-speed steels Р9 and Р18, as well as hard alloys Т15К6 for processing steel, copper and other viscous metals and grade ВК8 for processing cast iron and other brittle materials are used. metals High-speed steel reamers are made with welded shanks made of 45 steel. The bodies of prefabricated, adjustable and attachable reamers are made of structural steels.

Punch(Fig. 26) is a metalworking tool made from carbon tool steel U7 or U8, which is used for punching holes in sheet or strip metal or non-metallic materials with a thickness of no more than 4 mm.

Rice. 26. Punch: a – solid for a metal sheet; b – hollow for leather and plastics

The working part of the punch can have a round, rectangular, square, oval or other shape. A punch for leather and tin has a blind hole in the working part, which is connected to a longitudinal side hole passing through the wall of the lower part of the punch. Waste is removed through this hole.

Hole punching is performed when some damage to the surface in the hole area is tolerated and the cleanliness and precision of the hole is not required.

When working on drilling machines, the following safety requirements must be met.

Before starting work, you should check the technical condition of the drilling machine and tools. Start and stop the machine with dry hands.

It is necessary to work on the machine in accordance with the equipment operating instructions, as well as in accordance with the labor protection instructions. You should use special work clothes and be sure to match your hair to your headdress.

Parts must be correctly and securely fastened in a vice or fixture that is in good technical condition. When drilling small holes, the left hand holding the part should exert resistance opposite to the direction of rotation of the spindle. During the working stroke of the drilling machine spindle, you must not hold or brake the spindle, change the speed and feed, or clear the table or workpiece from chips.

The drill should be cooled with coolant using a brush or watering. Cooling with damp rags or rags is not allowed.

All damage that can be repaired must be repaired by a trained worker.

2.11. Threading and tapping tools

Thread cutting – This is the formation of a helical surface on the outer or inner cylindrical or conical surfaces of a part.

Cutting the helical surface on bolts, shafts and other external surfaces of parts can be done manually or by machine. Hand tools include: round split and continuous dies, as well as four- and hexagonal plate dies, dies for cutting threads on pipes. Die holders and clamps are used to secure the dies. The round die is also used for machine thread cutting.

Cutting external threads by machine can be done on lathes with thread cutters, combs, thread-cutting heads with radial, tangential and round combs, vortex heads, as well as on drilling machines with thread-cutting heads, on milling machines with thread-cutting cutters and on thread grinding machines with single-thread and multi-thread nym in circles.

Obtaining an external threaded surface can be achieved by rolling it with flat dies or round rollers on thread rolling machines. The use of thread rolling heads with axial feed allows you to roll external threads on drilling and turning equipment.

Threading in holes is performed taps manually and by machine. There are cylindrical and conical taps. Hand taps come in single, two-set and three-set. Typically, a set consisting of three taps is used: a rough one, indicated by one dash or the number 1; middle, indicated by two dashes or the number 2; and finishing, indicated by three dashes or the number 3 (Table 12, Fig. 27).

Table 12 Scope of application of hand taps


Rice. 27. Hand tool taps: a – draft; b – average; c – finishing

There are special taps: for dies (die taps with a long cutting part), for nuts, for pipes, for light alloys, and also with a conical working part. Taps can be used to cut threads in through and blind holes or to calibrate previously cut threads with master taps.

A driver with a fixed or adjustable square hole is placed on the shank of a hand tap, ending in a square head.

In some cases, combined taps are used, which can be used for drilling and threading.

Machine taps are used for cutting internal threads on all types of drilling and lathe machines. They can cut threads in one or more passes. In one pass, threads with a pitch of up to 3 mm are cut, and in 2–3 passes, threads with a larger pitch, especially long threads, as well as smooth threads in difficult-to-cut materials, regardless of the pitch, are cut.

Nut taps are used to cut threads in nuts on machines. They operate without reversing and when cutting, the nuts are threaded onto the shank. There are nut taps with straight and curved shanks.

For cutting large-diameter internal threads, thread-cutting heads with adjustable dies or converging dies are used.

Tap elements: working part, consisting of cutting and calibrating parts, and a shank. The working part has spiral cutting and longitudinal grooves for removing chips. Cutting edges are obtained at the intersection of spiral cutting and longitudinal grooves for chip removal. The tail end ends with a square head for installation in the chuck. Taps are made from carbon tool steel U12 and U12A, high-speed steel R12 and R18, alloy steel X06, XV, IH.

Helical surface- this is a surface described by a generating curve, uniformly rotating around an axis and at the same time performing uniform translational motion along this axis. In relation to the threaded surface, the generatrix is ​​a triangle (for metric and inch threads), a trapezoid (for trapezoidal threads) and a rectangle (for rectangular threads, for example, in jack lead screws).

Thread profile- this is a contour obtained by cutting the screw surface with a plane passing through the axis of the screw. The thread profile consists of the projections and valleys of the threads. The shaft axis is the axis of the helical surface. The thread parameters are outside diameter d, inner diameter d 1, medium diameter d 2, step R, thread profile angle d. The thread profile is divided into two parts: projections and valleys. Threads can be single-start or multi-start.

Under thread pitch one should understand the translational movement of the midpoint of the profile generatrix, corresponding to one full revolution relative to the thread axis.

The thread pitch is determined by the distance between the axes of two identical points of successive turns of the same name or the distance by which the nut moves along the screw when performing one full revolution for a single-start thread (Table 13, 14).

Table 13 Dimensions of conventional metric threads, mm Table 14 Inch threads

The helical surface of a multi-start thread can be considered as several helical grooves having one nominal diameter (hence, one nominal pitch, which in a multi-start thread is called a stroke t) and formed on one smooth cylindrical surface with entries evenly spaced around the circumference. Thus, the thread progress t– this is the distance between the nearest identical sides of the profile, belonging to the same screw surface, in a direction parallel to the thread axis.

Thread stroke is the relative axial movement of a screw or nut per revolution. If the thread is single-start, then the thread stroke t equal to thread pitch R. If the thread is multi-start, then the thread stroke t equal to the product of the step R by number of visits n:

Threads can be single-start or multi-start, as well as right-handed and left-handed. A multi-start thread is when one cutting stroke involves two or more thread profiles.

Depending on the thread configuration, there are metric (normal and small), inch, pipe, trapezoidal, symmetrical and asymmetrical, rounded, rectangular. They can be cylindrical or conical.

The profile angle of metric threads is 60°, inch cylindrical threads are 55°, inch conical threads are 60°, pipe cylindrical and conical threads are 55°, trapezoidal are 30°.

The designation of threads is given in table. 15.

Table 15 Thread designation

Depending on the profile, threads are divided into triangular, trapezoidal, symmetrical and asymmetrical, rectangular and rounded.

The M4 thread has a pitch of 0.7 mm; M6 – 1 mm; M8 – 1.25 mm; M10 – 1.5 mm; M12 – 1.75 mm; M14 – 2 mm; M16 – 2 mm; M18 – 2.5 mm; M20 – 2.5 mm; M22 – 2.5 mm; M24 – 3 mm; M27 – 3 mm; M30 – 3.5 mm.

In the past, inch threads were used more often, now metric threads are used, and inch threads are used less often.

In metric threads, there are 3 accuracy classes: precise (designation of fields for external threads is 4p, for internal threads - 4Н5Н), medium (designation of tolerance fields for external threads 6h, 6g, 6e and 6d, for internal threads - 5Н6Н, 6Н, 6G), coarse (designation of tolerance fields for external threads 8h, 8g, for internal threads – 7Н, 7G).

For trapezoidal threads there are two accuracy classes: medium (designation of the tolerance field for long external threads is 7p, 7e, and 8e, internal 7N and 8N); rough (designation of the tolerance zone for long external threads 8е, 8с, 9с, internal 8Н and 9Н).

Threads are distinguished by the nominal diameter of the thread, which is most often the outer diameter of the screw surface d, inner diameter d1, average diameter d 2 screws and nut hole inner diameter D 1, nut thread diameter D, average nut thread diameter D 2 most often equal d 2(Fig. 28).

Rice. 28. Section and thread profile: a – screw; b – nuts

The average screw diameter is determined by the formula:

d 2 = (d+ d 1)/2.

d o = d– 1,1P,

rod diameter d c for a triangular thread - according to the approximate formula:

d c = d– 0,1R.

The diameters of holes and threaded rods are given in table. 16 and 17.

Table 16 Diameters of holes for cutting triangular threads

Table 17 Diameters of rods for cutting triangular threads

Before cutting a thread, the rod must be free of rust; the lead-in chamfer must be removed on its end surface. When cutting threads in parts made of carbon and alloy structural steels, the following coolants are used: for taps - sulfofresol or a 5% solution of E-2 or ET-2 emulsion, for dies, dies, thread-cutting heads - sulfofresol, Industrial 20 oil.

For stainless and hard-to-cut steels, sulsrofresol, oleic acid or a liquid of the following composition is used: sulsrofresol - 60%, kerosene - 25%, oleic acid - 15%.

For gray cast iron, kerosene or Industrial 200 oil is used when tapping.

For aluminum and its alloys, use a 5% solution of emulsion E-2, ET-2 or a liquid of the following composition: Industrial 20 oil - 50%, kerosene - 50%.

For copper and its alloys, use a 5% solution of emulsion E-2, ET-2 or Industrial 20 oil.

Lubrication reduces friction, cools the tool, extends tool life and facilitates chip removal.

The main causes of defects in thread cutting are the following: discrepancy between the diameters of holes or rods and the thread being cut, damage to the tool, cutting threads without the use of lubrication, dull tools, poor fastening or poor installation of the tool, and lack of professional skills (Table 18).

Table 18 Defects in thread cutting

When cutting threads, there is a risk of injury to your hands from the sharp edge of the part or tool. Do not use your fingers to clear chips from hand tools; It is strictly forbidden to clean tools that are in motion on machines with your fingers.

2.12. Riveting works and riveting tools

Riveting – is the operation of obtaining a permanent connection of materials using rods called with rivets. A rivet ending with a head is installed in the hole of the materials being joined. The part of the rivet protruding from the hole is riveted in a cold or hot state, forming a second head.

Rivet connections are used:

in structures operating under vibration and shock loads, with high requirements for connection reliability, when welding of these connections is technologically difficult or impossible;

when heating of the joints during welding is unacceptable due to the possibility of warping, thermal changes in metals and significant internal stresses;

in connection cases various metals and materials for which welding is not applicable.

To make riveted connections, the following types of rivets are used: with a semicircular head, with a countersunk head, with a semi-countersunk head, tubular, explosive, split (Fig. 29). In addition, rivets with a flat conical head, a flat head, a conical head, a conical head and a head, and an oval head are used.

Rivets are made from carbon steel, copper, brass or aluminum. When connecting metals, select a rivet from the same material as the elements being connected.

A rivet consists of a head and a cylindrical shaft called the rivet body. The part of the rivet that protrudes from the other side of the material being joined and is intended to form the closing head is called the shank.

Rice. 29. Rivets: a – with a semicircular head; b – with a countersunk head; c – with a semi-concealed head; g – tubular; d – explosive; e – split

The length of a rivet with a semicircular head is measured to the base of the head (body length), the length of a rivet with a countersunk head is measured along with the head, the length of a rivet with a semi-countersunk head is measured from the edge of the transition of the sphere to the cone to the end of the body of the rivet.

The diameter of the rivet is determined by the diameter of the body and is measured at a distance of 6 mm from the base of the head. The diameter of the hole for the rivet during hot riveting should be 1 mm larger than the diameter of the rivet.

Steel rivets with a diameter of up to 14 mm can be riveted in a cold state. Rivets with a diameter of more than 14 mm are riveted hot. Rivet diameters from 10 to 37 mm increase in 3 mm increments.

Riveting uses drilled, pierced or punched holes. For strong, tight and tightly rivet joints, exclusively drilled holes are used.

Rivet joints can be overlapped, butt with one overlay, butt with two overlays symmetrically, butt with two overlays asymmetrically (Fig. 30).

Rice. thirty. Types of rivet connections: a – overlap; b – end-to-end with one overlay; c – end-to-end with two overlays, symmetrical; g – butt with two overlays, asymmetrical

From the point of view of strength and density, the following types of rivet joints are used: strong, from which only mechanical strength is required; dense, to which only the requirements of density and tightness are imposed; durable and dense, from which, in addition to mechanical strength tightness of the connection is also required. The latter is achieved by enlarging the head and the presence of a rivet head, rather frequent placement of rivets by counter-chasing the edges of the joined sheets and rivet heads.

Rivet seams are divided into longitudinal, transverse and inclined. They can be single-row, double-row or multi-row (parallel and with staggered rivets). Sutures can be complete or incomplete (Fig. 31).

Rice. 31. Types of rivet seams: a – single-row; b – double-row; c – multi-row full; g – multi-row incomplete

Before riveting various types of riveted joints, the riveting pitch should be determined (step this series- this is the distance between the two closest rivets in this row, the seam pitch is the smallest multiplicity of all steps in the rows) and the distance from the rivet axis to the edge of the strip.

Depending on the diameter of the rivet, the need and the type of riveting, manual and mechanical riveting are used.

The closing head is produced by impact riveting and pressure riveting. Impact riveting is versatile, but noisy; Pressure riveting is of higher quality and quieter.

For manual riveting, hammers are used to form the rivet head, crimping, supports, clamps and pliers.

For mechanical riveting, pneumatic or electric hammers, riveting pliers, rivet head supports, and consoles are used. Large industrial enterprises use riveting machines - eccentric and hydraulic.

Rivets can be heated in blacksmith's forge, contact, industrial frequency currents on electric heating installations, as well as gas flames.

Incorrect riveting occurs due to an underheated or overheated rivet, poor fit of the elements being connected to each other, an error in forming the head, an excessively short or long rivet body, curvature of the rivet body in the hole, and also due to the hole drilled for the countersunk head being too deep.

For riveting it is necessary to use good tool. You should wear mittens on your hands and protect your eyes with goggles. It is necessary to correctly install the rivet head into the support or console, and correctly install the crimp on the rivet body. During riveting, do not touch the crimp with your hand.

2.13. Scraping and scraping tools

Scraping – This is the process of obtaining the accuracy of shapes, sizes and relative positions of surfaces required by operating conditions to ensure their tight fit or tightness of the connection.

When scraping, thin chips are cut from uneven surfaces that have already been previously processed with a file or other cutting tool.

Scraping tools are called scrapers. For the manufacture of scrapers, tool carbon steels U10, U10A, U12, U12A, alloy steel X05, as well as carbide plates inserted into steel holders are used. Used and worn-out triangular or flat files can also be used as scrapers after proper grinding.

There are manual and mechanical scrapers. They can be flat one-sided and double-sided, solid and with inserted plates, triangular solid and triangular one-sided, semicircular one-sided and double-sided, spoon-shaped and universal (Fig. 32).

A universal scraper consists of a replaceable plate (the working part of the scraper), a body, a clamp, a screw and a handle.

When scraping, cast iron plates are used to check the surfaces of flat parts, flat and triangular rulers to check the flatness of the surface, prisms, plates in the form of a rectangular parallelepiped, control rollers, probes and other tools to control the quality of scraping and lapping. In addition to the tools mentioned, brushes and cleaning materials are used.

Rice. 32. Metalwork scrapers: a – triangular; b – spoon-shaped; c – flat with a replaceable hard alloy plate

Scraping is used when it is necessary to remove traces of processing with a file or other tool, and also when it is necessary to obtain a high degree of accuracy and low surface roughness of machine parts connected to each other. Scraping is especially often used when processing parts of friction pairs.

Before scraping, you should check the degree of surface roughness and the areas of unevenness to be scraped. Plates, rulers, prisms, rollers, and probes are used to detect surface irregularities. When scraping paint, scraping paint is used. In some cases, scraping is carried out for shine.

To scrape parts for paint, use a slab or ruler, as well as paint.

As a paint for scraping, use a mixture of machine oil with Parisian blue or ultramarine, which has the consistency of a light paste. Sometimes a mixture of machine oil and soot is used.

The paint is applied in a thin layer to the slab or ruler with a brush or clean rag, after which the slab or ruler is applied to the surface of the part intended for scraping. After several circular movements of the plate or back-and-forth movements of the ruler along the part or part on the plate, the part is carefully removed from the plate. Painted spots that appear on the part indicate irregularities protruding on the surface of the part; irregularities are removed by scraping.

During the grinding of the part onto the paint plate, larger or smaller painted spots appear on the surface of the part, with light spaces between them. Colored spots appear due to unevenness on this surface.

The highest irregularities on the surface have a lighter color compared to the paint due to some abrasion of the paint during grinding movements. The main convexities are characterized good coverage paint and therefore have a thick color. Light and shiny spots on the surface of the part indicate depressions on the surface that are not covered with paint.

The sequence in which stains are removed from the surface determines their color.

Scraping begins from the most protruding places, indicated by a light color of paint. This is followed by densely colored spots. Light spots are not scraped.

The degree of accuracy and roughness of the surface is determined by the number of paint spots in a square with a side of 25 mm (about 16 - good scraping, 25 - very precise scraping).

The disadvantages of scraping are the processing is too slow and labor intensive, which requires great precision, patience and time from the mechanic. The advantage of this type of processing is the ability to obtain high precision (up to 2 microns) with simple tools. The advantages also include the ability to obtain precise and smooth shaped surfaces, processing closed surfaces and surfaces until they stop. Cast iron and steel surfaces of low hardness are good for scraping.

Hardened steel surfaces should be ground.

When scraping, it is necessary to maintain cleanliness and order around the workplace. The tool must be used carefully and with skill, put away in a drawer during breaks between work and after finishing it. The scraper should always be held so that the cutting part faces away from the person working. The scraper must be well sharpened. When scraping, be sure to remove sharp edges from parts.

2.14. Grinding and grinding machines

Grinding is the processing of parts and tools using rotating abrasive or diamond grinding wheels, based on cutting off a very thin layer of material in the form of tiny chips by the grains of the wheel from the surface. The purpose of grinding is to obtain surfaces of parts with low roughness and very precise dimensions.

The simplest and most common grinding machine is a grinder (Fig. 33). They are widely used in both small workshops and large enterprises. Sharpeners come in different designs and capacities: single and double, stationary and tabletop.

Rice. 33. Double sharpener

For grinding, hand-held electric grinders are also used, less often pneumatic ones. Grinding machines are cylindrical grinding, internal grinding, surface grinding, centerless grinding, sharpening and special (thread grinding and gear grinding, spline grinding, etc.).

As a result of incorrect choice of depth and feed, carelessness in bringing the grinding wheel to the part (or, conversely, the part to the wheel), damage and even rupture of the grinding wheel or part may occur, and burns may also appear, indicating structural changes in the surface of the material. Cooling must be used when grinding. Soda solution is used as a coolant.

When grinding, it is necessary to correctly select the appropriate grinding wheel, balance it and set the design speed. The grinding wheel should be properly secured and protected with a guard. To grind parts that are held in your hands, use a stop located at a distance of 2–3 mm in front of the grinding wheel. When sanding, use safety glasses. Grinding must be carried out in accordance with the machine maintenance instructions.

2.15. Lapping, polishing and surface finishing

Lapping – This is the removal of the thinnest layers of metal using fine-grained abrasive powders in a lubricant environment or diamond pastes applied to the surface of the tool (lapping). Used as a tool lapping, made of gray cast iron with pearlitic structure or other soft metal.

This is one of the most precise methods of surface treatment of metal parts. As a result of this treatment, all irregularities, as well as irregularities resulting from previous processing, are removed from the surface of the workpiece, while simultaneously achieving a very high degree of plane accuracy (1 μm). The purpose of lapping is to obtain accurate fits of the contacting surfaces of machine parts, as well as the accurate execution of other surfaces, for example, in reference tiles.

There are two types of lapping: lapping with an abrasive that penetrates into the surface of the lap; lapping with a non-charging abrasive.

The first type of lapping is the most common and is carried out with an abrasive freely supplied to the lap in a mixture with a liquid lubricant or with an abrasive previously loaded into the lap in a mixture with a viscous lubricant.

In accordance with the specified types of lapping, lappings are divided into manual, machine-manual, machine (mechanical) and assembly.

Lappings have the form of tiles, lapping plates, rollers, cones, circles, and can also have a complex configuration in accordance with the type of surface of the workpiece, and they can be monolithic or expanding (Fig. 34).

Rice. 34. Lappings: a – for shafts; b – for holes; c – disk; g – conical

Lapping materials are divided into pastes, lapping powders and cloth.

Lapping paste– this is a mixture of chromium oxide, silicon, stearic acid, as well as a small amount of fat and machine oil; Available in several varieties. Diamond, white and normal electrocorundum, boron carbide, glass, polishing crocus, abrasive mineral, and quicklime are used as polishing powders. Products made of non-ferrous metals and alloys are ground in with non-charging abrasives. The grain size of abrasive powders is selected depending on the purpose of the operation: for rough grinding - coarse-grained, for final grinding - fine-grained.

Kerosene serves as a lubricant for free flow of abrasive, and gasoline for particularly fine grinding; in case of preliminary caricature of laps - kerosene, machine oil. By adding stearic acid to kerosene, the process is accelerated.

For lapping with non-charging abrasive, which ensures the highest surface quality and gloss, relatively soft abrasive materials are used. In this case, the hardness of the lap must be higher than the hardness of the surface of the part being ground. The abrasives used are chromium oxide, crocus (iron oxide). The lubricant is kerosene, machine oil for steel and a mixture of animal fat and machine oil for copper and its alloys.

Abrasive mineral, usually called emery, is a fine-grained natural corundum with a dark color. An abrasive mineral in the form of free grains or grains glued to an elastic substrate (canvas, paper) is used for polishing and lapping. The grain size is determined in the same way as in other abrasive materials. The coarser the grain, the higher the number used to designate the abrasive mineral.

Lappings are made from gray pearlitic cast iron with a hardness within HB 180–200, mild steel, brass, copper, lead and hardwood. Before you start working, the lap should be primed, that is, rub abrasive powder into its working surface using a steel rod or roller (if the lap is made of soft material) or using the part being ground (if the lap is made of cast iron).

Polishing is a finishing treatment in which surface irregularities are smoothed mainly as a result of their plastic deformation and (to a lesser extent) cutting off the protrusions of microirregularities.

Polishing is used to make the surface of a part shine. As a result of polishing, surface roughness is reduced and a mirror finish is achieved. The main purpose of polishing is decorative surface treatment, as well as reducing the coefficient of friction, increasing corrosion resistance and fatigue strength.

Polishing is done with soft circles (felt, felt, cloth), onto which a mixture of abrasive powder and lubricant or polishing paste is applied.

Emery and electrocorundum powders, chromium oxide, crocus, and Vienna lime are used as abrasive powders. Grease and mixtures of paraffin and wax are used as oils and binding elements of micropowders with a soft wheel or tape, applied to the wheels in a heated state. In some cases, the abrasive powder is glued to the wheel with wood glue or synthetic glue BF-2. Small parts polished in a rotating drum using hardened steel balls with a diameter of 3–8 mm. The polishing operation can be done manually or by machine.

“Inducing frost” on the surface- this is one of the ways final finishing metal surface, giving it good appearance by applying small marks on it in a specific pattern. These risks are carried out carefully and accurately using a scraper, manually or mechanically.

Matting- This is giving the metal surface a matte ash-gray color. This operation is performed mechanically on small forged, cast, filed or cast parts using steel or copper wire brushes in a rotating motion. Before matting, the metal surface is moistened with soap solutions.

Oxidation- this is the formation of a thin layer of blue or dark blue oxide on the surface of a steel part or product. The most common method of oxidation during metalwork is based on covering a well-cleaned item from rust with a thin layer of linseed oil and heating it in a furnace over hot coke.

Blackening of a steel part is carried out in the following sequence: surface polishing, degreasing with Vienna lime, washing, drying, coating with an etching solution. After coating with the etching solution, the part is dried at a temperature of 100 °C for several hours, after which it is exposed to steam and hot water. Then the part is cleaned wet with a wire brush.

Coloring- This is coating the surface with a layer of paint or varnish in order to prevent corrosion and give the part or product a marketable appearance. Painting is done manually with a brush or mechanically (with a paint gun). Paints can be water-based, oil-based, nitro paints and synthetic enamels.

Before painting, the object should be thoroughly cleaned, washed with a warm alkali solution, then with clean water and dried. After this, the metal surface is primed with an appropriate primer or red lead. The surfaces of large objects or machine parts, the surfaces of which must be flat and smooth, must be puttied before painting. After the putty has dried, the surfaces are sanded, then primed and painted.

Materials and pastes used for lapping contain (among others) harmful and toxic substances. Therefore, when grinding and finishing surfaces, general precautions should be taken (if possible, do not touch them with your fingers, wash your hands). Tools and machines must be technically sound and used in accordance with the operating instructions. Paints should be stored in fireproof boxes. When painting, spraying and polishing, fire safety measures should be taken. The worker must wear protective clothing and a respirator. When performing these operations in enclosed spaces, intensive ventilation must be provided.

2.16. Soldering, tinning, filling of inserts, metallization and gluing

Soldering – is the process of creating a permanent joint between metals using a filler bonding material called solder, Moreover, the solder is brought to a liquid state during the soldering process. The melting point of solder is much lower than that of the metals being joined.

Permanent connection of metals by soldering can be made with a soldering iron, in a gas flame, soldering in ovens, in a bath, chemically, autogenous soldering, etc.

Soldering requires soldering irons, solders, as well as cleaning, etching and surface oxidation-preventing agents during soldering.

Soldering iron – this is a hand tool various shapes and masses. The part of the soldering iron that is directly used for soldering is made of copper. Heating of the copper part of the soldering iron can be done using electricity (electric soldering iron), over a gas flame (gas soldering iron) or in a forge.

Gasoline blowtorches can be used to heat soldering irons and some warm-up of the metals being joined (Fig. 35).

Rice. 35. Soldering irons: a – ordinary, heated by flame; b – electric; c – blowtorch

Soft solders are tin-lead (with or without the addition of antimony). The melting point of these solders is from 183 to 305 °C.

The hardness of the solder is determined by the brand and chemical composition metals used for soldering. Solders are made from copper, brass, silver, nickel and aluminum. In addition, there are heat-resistant and stainless steel solders based on nickel, manganese, silver, gold, palladium, cobalt and iron. The melting temperature of hard solders ranges from 600 to 1450 °C

Chemical cleaning and etching agents include: hydrochloric acid, zinc chloride, borax, boric acid, ammonia. You can clean the surface by mechanical means, an abrasive material or a file or metal brushes. During soldering, the surface is protected from oxidation by means such as stearin, turpentine and rosin.

Zinc chloride is a chemical compound of hydrochloric acid and zinc. It is obtained by placing pieces of zinc in dilute hydrochloric acid. After the completion of the reaction (cessation of hydrogen evolution), the zinc chloride should be poured into another container, leaving the sediment in the original container. The acid should be diluted by adding water to it, and not vice versa.

Soft solders are used for permanent connections and sealing of metals with insignificant requirements for strength and tensile and impact endurance of the joint, hard solders are used for permanent and hermetic connections of high strength and tensile and impact endurance.

Solders are available in the form of sheet, strip, rod, wire, mesh, blocks, foil, grains, powders and solder paste.

Tinning called surface coating metal products a thin layer of tin or tin-based alloy. Galvanizing It is produced by cold electrolytic or hot coating of metal products with a thin layer of zinc.

Tinning and galvanizing are used, for example, in plumbing in the production of household products, in the food industry, in construction as a means of protection against corrosion, oxidation and the formation of chemical compounds that are harmful to health and destroy metal.

For tinning and galvanizing, depending on the part and its purpose, you need to have pure tin, zinc or their alloys, a blowtorch or gas torch, cleaning agents necessary for degreasing and cleaning surfaces subject to tinning or galvanizing, baths for melting tin or zinc, and a wiping machine. material and pliers.

Bearing alloy is an alloy of metals (tin, lead, copper, antimony, etc.) used for the manufacture of plain bearing shells by casting. In bearing alloy shells, very little friction occurs when the shafts rotate in them.

The selection of bearing alloys that best meet the given conditions is carried out taking into account their physical and mechanical properties, in particular antifriction properties, the ability to withstand certain pressures and temperatures, hardness, viscosity, casting qualities, etc.

The properties of a bearing alloy are determined by its main component.

There are bearing alloys based on tin, lead, aluminum, cadmium, zinc, copper (bronze, brass) and other bases. The most commonly used bearing alloys are tin, lead or copper.

Liquid bearing alloy is prepared in a graphite or cast iron crucible. The crucible is heated with a blowtorch, on a forge, or with the flame of gas burners.

The casting temperature for tin- or lead-based bearing alloys ranges from 450 to 600 °C. The melting point of bronze ranges from 940 to 1090 °C. Crushed material is poured onto the molten bearing alloy before casting. charcoal, which protects the alloy from oxidation.

Spray metallization- This is the application of a metal coating to the surface of a product by spraying molten metal under pressure.

This operation is performed using special guns. Metallization is used to protect products from corrosion, as well as to repair worn machine parts, to correct defective castings, and also to correct defects resulting from cutting.

By gluing called permanent connection of product parts by coating the connected surfaces of the product with a substance (or mixture of substances) called glue, connecting them and maintaining them under some load until the glue hardens. In some cases, heating of glued parts is used.

Glue is a viscous substance with adhesive properties. The adhesive consists of a filler, a hardener, a solvent, a binder, and a plasticizer.

Depending on the purpose of the glue, wood flour, crushed asbestos, metal powders, their oxides, etc. are used as fillers. Depending on the hardener, cold- and hot-curing adhesives are distinguished.

There are the following types of glues: protein or vegetable (starch, dextrin, gum arabic, rubber glue), animal (bone, fish, casein, flesh, carpentry, etc.), synthetic (carbinol, urea, resin, etc.).

In the plumbing industry, the most common synthetic adhesives are: phenolic BF-2, BF-4, VK-32-200, VS-350, epoxy ED-5, ED-6, VK-32-EL, polyamide PPFE-2/10, MPF-1, carby-nol and polyurethane PU-2. In addition to metals, these adhesives can also be used to glue non-metallic products such as wood, glass, ceramics, artificial materials, leather, fabrics, paper, etc.

In plumbing, glue is used primarily to join both metal parts and metal parts to non-metal parts. For this purpose, carbinol glue is used.

The bonded surfaces should be thoroughly cleaned mechanically, then degreased with aviation gasoline, benzene or toluene. After degreasing, the product is dried without touching the surfaces intended for gluing with your fingers.

Of the non-ferrous metals, copper is the worst at gluing; brass and bronze are slightly better.

A worker performing metallization, tinning, soldering or gluing operations comes into contact with molten metal, acids, alkalis and vapors of various substances that are caustic and harmful to the body. The rooms in which these operations are performed must have good ventilation.

Workers must have protective clothing, glasses and gloves. The blowtorch must be technically sound. When pumping fuel, you cannot create high pressure, you should also not add fuel to a heated lamp. Acids and alkalis should be kept in glass bottles, and they must be diluted by adding acids to water, and not vice versa. The workplace should be free of rags, spilled oil and grease.

In the work of a mechanic in the manufacture, repair or assembly of parts of mechanisms and machines, there is often a need to obtain a wide variety of holes in these parts. To do this, the operations of drilling, countersinking, countersinking and reaming holes are performed.

The essence of these operations is that the cutting process (removal of a layer of material) is carried out by rotational and translational movements of the cutting tool (drill, countersink, etc.) relative to its axis. These movements are created using manual (rotary, drill) or mechanized (electric drill) devices, as well as machine tools (drilling, lathe, etc.).

Drilling is one of the types of making and processing holes by cutting using a special tool - a drill.

Like any other cutting tool, the drill works on the wedge principle. According to their design and purpose, drills are divided into feather, spiral, centering, etc. modern production Mostly twist drills are used, and less often special types of drills are used.

A twist drill consists of a working part, a shank and a neck. The working part of the drill, in turn, consists of a cylindrical (guide) and cutting parts.

There are two helical grooves on the guide part, through which chips are discharged during the cutting process.

The direction of helical grooves is usually right. Left-handed drills are used very rarely. Along the grooves on the cylindrical part of the drill there are narrow stripes called ribbons. They serve to reduce friction between the drill and the walls of the hole (drills with a diameter of 0.25-0.5 mm are made without bands).

The cutting part of the drill is formed by two cutting edges located at a certain angle to each other. This angle is called the vertex angle. Its value depends on the properties of the material being processed. For steel and cast iron of medium hardness it is 116-118°.

The shank is designed to secure the drill in the drill chuck or machine spindle and can be cylindrical or conical. The conical shank has a tab at the end, which serves as a stop when pushing the drill out of the socket.

The neck of the drill, connecting the working part with the shank, serves to release the abrasive wheel during the grinding process of the drill during its manufacture. The brand of the drill is usually indicated on the neck.

Drills are made primarily from high-speed steel grades P9, P18, P6M5, etc. Metal-ceramic hard alloys of grades VK6, VK8 and T15K6 are increasingly being used. Hard alloy plates are usually equipped only with the working (cutting) part of the drill.

During operation, the cutting edge of the drill becomes dull, so the drills are periodically sharpened.

Drills are used not only for drilling blind (drilling) and through holes, i.e. obtaining these holes in solid material, but also drilling - increasing the size (diameter) of already obtained holes.

Countersinking is the processing of the top of holes in order to obtain chamfers or cylindrical recesses, for example, for the countersunk head of a screw or rivet. Countersinking is performed using countersinks with a larger diameter drill; Countersinking is the processing of holes produced; by casting, stamping or drilling, to give them a cylindrical shape, improving accuracy and surface quality. Countersinking is performed with special tools - countersinks (20, in). Countersinks can be with cutting edges on a cylindrical or conical surface (cylindrical and conical countersinks), as well as with cutting edges located at the end (end countersinks). To ensure alignment of the hole being machined and the countersink, a smooth cylindrical guide part is sometimes made at the end of the countersink.

Countersinking can be a finishing process or preparatory to reaming. In the latter case, when countersinking, an allowance is left for further processing.

Reaming is the finishing of holes. In essence, it is similar to countersinking, but provides higher accuracy and low surface roughness of holes. This operation is performed using mechanic (manual) or machine (machine) reamers. The reamer consists of a working part, a neck and a shank. The working part is divided into intake, cutting (conical) and calibrating parts. The calibrating part closer to the neck has a reverse cone (0.04-0.6) to reduce friction of the reamer against the walls of the hole. The teeth on the working part (helical or straight) can be spaced evenly around the circumference or unevenly. Reamers with uneven tooth pitch are usually used for manual processing of holes. They allow you to avoid the formation of the so-called cut, i.e. obtaining holes of irregular cylindrical shape. The manual reamer shank has a square for installing a driver. The shank of machine reamers with a diameter of up to 10 mm is made cylindrical, while other reamers have a conical shank with a foot, like a drill.

For roughing and finishing of holes, a set (set) of reamers is used, consisting of two or three pieces. Reamers are made from the same materials as other cutting tools for making holes.

The considered hole processing operations are performed mainly on drilling or lathes. However, in cases where the part cannot be installed on the machine or the holes are located in hard-to-reach places, processing is done manually using cranks, hand or mechanized (electric and pneumatic) drills.

A driver with square holes is used when working with a tool that has a square on the shank, for example a manual reamer.

A hand drill consists of a frame with a stop /, which is pressed to give the drill a translational movement, a gear with a manual drive, a handle for holding the drill 6, a spindle A with a chuck installed on it for securing the cutting tool.

In order to facilitate labor when processing holes and increase its productivity, mechanized drills (hand-held drilling machines) are used. They can be electric or pneumatic. The practice of working in training workshops is wider; Electric drills are used, since pneumatic ones require compressed air to be supplied to them.

Electric drilling machines are manufactured in three types: light, medium and heavy. Lightweight machines are designed for drilling holes with a diameter of up to 8-9 mm. The body of such machines is often pistol-shaped.

Medium type clippers usually have a closed handle; on the back of the case. They are used for drilling holes up to 15 mm in diameter.

Heavy type machines are used to produce and process holes with a diameter of 20-30 mm. They have two handles on the body (or two handles and a stop) to hold the machine and transmit translational motion to the working tool.

Let's consider the design of vertical drilling machines using the example of a machine type 2A135. This machine is designed for drilling and reaming blind and through holes up to 35 mm in diameter, as well as countersinking, countersinking, reaming and threading.

It has a frame, in the upper part of which a spindle head is installed. Inside the head box there is a gearbox that transmits rotation from the electric motor to the spindle. Axial movement of the tool is carried out using a feed box mounted on the frame. The workpiece to be processed is fixed on a table, which can be raised and lowered using a handle, which makes it possible to process workpieces different heights. The machine is mounted on a plate

When working on drilling machines, various devices are used to secure workpieces and cutting tools.

Machine vice - a device for securing workpieces different profiles. They can have replaceable jaws for clamping parts of complex shapes.

Prisms are used to secure cylindrical workpieces.

Drill chucks hold cutting tools with cylindrical shanks.

Using adapter bushings, cutting tools are installed whose shank cone size is smaller than the machine spindle cone size.

Drilling machines can perform all basic operations for producing and processing holes by drilling, countersinking, countersinking and reaming.

To set up a machine for a particular type of hole processing, it is important to correctly set the cutting speed and feed.

The cutting speed (m/min) during drilling is the distance traveled in the direction of the main movement by the point of the cutting edge most distant from the axis of the tool per unit time.

The cutting speed is selected depending on the properties of the material being processed, the diameter, material and sharpening shape of the cutting part of the tool and other factors.

In accordance with the obtained tool rotation speed, the machine spindle speed is set.

Feed is the amount of movement of the cutting tool relative to the workpiece along its axis per revolution. It is measured in millimeters per revolution (mm/rev).

Feed values ​​also depend on the properties of the material being processed, the drill material and other factors.

When determining cutting speed and feed, the depth of cut is taken into account. Depth of cut t for drilling and other types of hole processing is the distance between the machined and machined surfaces, measured perpendicular to the axis of the workpiece.

Since the depth of cut when machining holes is a relatively constant value (specified by the drawing or machining allowance), the main influence on the processing performance will be exerted by the selected values ​​of cutting speed and feed.

As the cutting speed increases, the machining process accelerates. But when working at too high speeds, the cutting edges of the tool quickly become dull and it has to be sharpened frequently. Increasing the feed also increases machining productivity, but this usually increases the surface roughness of the hole and dulls the cutting edge.

Thread cutting techniques, and especially the cutting tool used, largely depend on the type and profile of the thread.

Threads can be single-start, formed by one helical line (thread), or multi-start, formed by two or more threads.

According to the direction of the helical line, the threads are divided into right and left.

The profile of a thread is the section of its turn with a plane passing through the axis of the cylinder or cone on which the thread is made.

To cut a thread, it is important to know its basic elements: pitch, outer, middle and inner diameters and the shape of the thread profile.

The thread pitch S is the distance between two points of the same name on adjacent thread profiles, measured parallel to the thread axis.

Outer diameter d - the largest distance between the outermost points, measured in the direction perpendicular to the thread axis.

Internal diameter di is the smallest distance between the extreme internal points of the thread, measured in a direction perpendicular to the axis.

Average diameter di is the distance between two opposite parallel flanks of a thread profile, measured in a direction perpendicular to the axis.

Base of thread Top of thread

According to the shape of the thread profile, they are divided into triangular, rectangular, trapezoidal, thrust (profile in the form of an unequal trapezoid) and round.

Depending on the sizing system, threads are divided into metric, inch, pipe, etc.

In metric threads, the angle of the triangular profile φ is 60°, the outer, middle and inner diameters and thread pitch are expressed in millimeters. Example of designation: M20X X1.5 (the first number is the outer diameter, the second is the pitch).

Pipe thread differs from inch thread in that its initial size is not the outer diameter of the thread, but the diameter of the hole of the pipe on the outer surface of which the thread is cut. Example of designation: pipes. 3/U (numbers are the internal diameter of the pipe in inches).

Thread cutting is carried out on drilling and special thread-cutting machines, as well as manually.

When manually processing metals, internal threads are cut with taps, and external threads are cut with dies.

Taps according to their purpose are divided into manual, machine-hand and machine, and depending on the profile of the thread being cut - into three types: for metric, inch and pipe threads.

The tap consists of two main parts: the working part and the shank. The working part is a screw with several longitudinal grooves and is used for direct thread cutting. The working part, in turn, consists of an intake (cutting) and a guide (calibrating) parts. The intake (cutting) part does the main work when cutting threads and is usually made in the form of a cone. The calibrating (guiding) part, as the name suggests, guides the tap and calibrates the hole.

Longitudinal grooves serve to form cutting feathers with cutting edges and accommodate chips during the thread cutting process.

The shank of the tap is used to secure it in the chuck or in the driver during operation.

To cut a thread of a certain size, hand (mechanism) taps are usually made in a set of three pieces.

metal mechanic detail

After making holes in a solid material, they are processed to increase the size and reduce the roughness of surfaces, as well as the processing of previously obtained holes (for example, by casting, punching, etc.). Hole machining in progress in several ways, depending on what parameters of the accuracy and roughness of the hole surface are specified in the drawing. In accordance with the chosen processing method, the tool for its implementation is also selected. When machining holes There are three main types of operations: drilling, countersinking, reaming and their varieties: drilling, countersinking, countersinking.

Drilling

Drilling is an operation for the formation of through and blind holes in a solid material, performed using a cutting tool - a drill. There are manual drilling - with manual pneumatic and electric drilling devices (drills) and drilling on drilling machines. Manual drilling devices are used to produce holes with a diameter of up to 12 mm in materials of low and medium hardness (plastics, non-ferrous metals, structural steels, etc.). To drill and process holes of larger diameter, increase labor productivity and quality of processing, desktop drilling and stationary machines are used - vertical drilling and radial drilling.

One of the types of drilling is reaming - increasing the diameter of a previously drilled hole. Drills are used as tools for drilling holes, as well as for drilling. It is not recommended to drill holes made in a workpiece by casting, forging or stamping. Such holes have different hardness along the surface of the hole due to the scale formed during casting, as well as due to the uneven concentration of internal stresses in the metal on different areas of the surface of the holes produced by forging or stamping. The presence of places with uneven and increased surface hardness leads to changes in the radial loads on the drill during the processing of the hole, which leads to a displacement of its axis and also causes drill breakage. Processing holes by drilling and reaming allows you to obtain dimensional accuracy of the machined hole up to 10th grade and a roughness of the machined surface up to Rz 80.

Countersinking

Countersinking is an operation associated with the processing of pre-drilled, stamped, cast or other methods of holes in order to give them a more regular geometric shape (elimination of deviations from roundness and other defects), as well as to achieve higher accuracy compared to drilling (up to 8 th quality) and lower roughness (up to Ra 1.25). Countersinking is carried out either on tabletop drilling machines (for small hole diameters) or on stationary drilling equipment installed on the foundation. Manual drilling equipment is not used for countersinking, since it cannot provide the required accuracy and surface roughness. Types of countersinking include countersinking and countersinking.

Basic rules for countersinking holes:

Drilling and countersinking of holes must be done with one installation of the part (workpiece) on the machine, i.e., changing only the processing tool;

When countersinking unprocessed holes in body parts, special attention should be paid to the reliability of installation and the strength of the part;

It is necessary to strictly observe the amount of allowance for countersinking, guided by the corresponding table;

Countersinking should be done in the same modes as drilling;

It is necessary to follow the same labor protection rules as when drilling.

Countersinking

Countersinking- This is the processing at the top of drilled holes of cylindrical or conical recesses for the heads of screws and rivets, as well as chamfers. The operation is performed using a special tool - a countersink.

Basic rules for countersinking holes:

It is necessary to follow the correct sequence of countersinking holes: first drill the hole, and then countersink it;

Drilling a hole and countersinking it should be done from one installation of the workpiece (part), changing only the tool;

Countersinking should be performed with manual feed of the countersink and low spindle speed (no more than 100 rpm) using emulsion; the depth of countersinking should be checked with a caliper or machine ruler;

When countersinking holes with a cylindrical countersink, when the diameter of the trunnion is larger than the diameter of the hole, it is necessary to first drill a hole along the diameter of the trunnion, and then countersink the hole. The final operation is drilling the hole to a given size.

Countering- this is an operation for cleaning the end surfaces when processing bosses for washers, nuts, and retaining rings. The operation is performed using a special tool—a counterbore, which is mounted on special mandrels.

Deployment

Deployment — This is an operation to rework previously drilled holes. with a high degree of accuracy (up to 6th grade) and low roughness (up to Ra 0.63). Reaming processing is carried out after preliminary drilling, reaming and countersinking of the hole using reamers, which are divided into roughing and finishing, manual and machine. Deployment is carried out both manually and on machines, usually stationary. The design of the tool is selected depending on the processing method used.

Basic rules for drilling holes:

It is necessary to strictly observe the amount of allowance for deployment, guided by the corresponding table;

Manual reaming should be performed in two steps: first rough and then finishing;

In the process of reaming a hole in a steel workpiece, it is necessary to generously lubricate the surface to be treated with emulsion or mineral oil; cast iron workpieces should be reamed dry;

Manual reaming should only be done clockwise to avoid scoring the hole walls with chips;

During processing, the reamer should be periodically cleared of chips;

The accuracy of processing of reamed holes should be checked with gauges: cylindrical - go-through and non-go-through; conical - according to the maximum risks on the caliber. The expanded conical hole can be checked with a “pencil” control pin;

Drilling and reaming holes on a drilling machine using a machine reamer must be done from one installation of the workpiece, changing only the processing tool.

TO category:

Car maintenance

Main types of locksmith work

Marking
]

Rice. 30. Marking plate

Marking is the drawing of boundaries on the surface of the workpiece in the form of lines and points corresponding to the dimensions of the part according to the drawing, as well as axial lines and centers for drilling holes.

If the marking is made in only one plane, for example on sheet material, then it is called planar. Marking the surfaces of the workpiece located under different angles to each other is called spatial. The workpieces are marked on a special cast iron plate (Fig. 30), called a marking plate, installed on a wooden table so that its upper plane is strictly horizontal.

Tools for marking and. When marking, use various marking tools.

The scriber (Fig. 31) is a steel rod with sharp, hardened ends. A scriber draws thin lines on the surface of the workpiece using a ruler, template or square.

Markers are used to apply horizontal lines on the workpiece parallel to the surface of the marking plate. Reismas (Fig. 32) consists of a base and a stand fixed in its center, on which there is a movable clamp with a scriber that rotates around its axis. The movable clamp can move along the stand and be secured to it in any position with a clamping screw.

Rice. 31. Scribbler

The marking compass (Fig. 33) is used for drawing circles and curves on the workpiece to be marked.

Rice. 32. Reismas

Rice. 33. Marking compass

For precise marking, use a height gauge (Fig. 34). A rod with a millimeter scale is firmly fixed on a massive base. A frame with a vernier and a second micrometric feed frame move along the rod. Both frames are secured to the rod with screws in any desired position. The replaceable scriber leg is attached to the frame with a clamp.

Marking calipers are used for drawing circles of large diameters with direct setting of dimensions. A marking caliper (Fig. 35) consists of a rod with a millimeter scale printed on it and two legs, of which the leg is fixedly mounted on the rod, and the leg is movable and can be moved on the rod. The movable leg has a vernier. Hardened steel needles are inserted into both legs. The needle of the movable leg can be moved up and down and secured with a screw in the desired position.

Rice. 34. Height gauge

Rice. 35. Marking caliper

Rice. 36. Center finder

The center finder is designed to determine the center of the end of a cylindrical workpiece (Fig. 36). The center finder consists of a square with shelves located at an angle of 90° to each other, and a leg, the inner side of which divides the right angle of the square in half. To determine the center, the center finder is installed so that the flanges of the square touch the cylindrical surface of the workpiece. A scriber is drawn along the inside of the leg, thus marking a diameter line, then the center finder is turned 90° and a second diameter line is drawn. The intersection point of these lines will be the center of the end of the cylindrical workpiece.

A scale altimeter (Fig. 37) is used for marking in cases where it is necessary to set the tip of the scriber at a certain height. It consists of a fixed scale ruler attached to a cast iron square, a movable ruler moving along guide bases, and a sighting slide with a fine line. When marking, the sighting slider is installed so that its thin line coincides with the main axis of the workpiece, and is secured in this position. After this, the zero division of the movable ruler is placed against the thin line of the sighting slider and the distance (height) from the main axis of the workpiece to the other axes is read on the movable ruler.

The punch is used to make small indentations on the marking lines of the workpiece, so that these lines are clearly visible and are not erased during the processing of the workpiece. The center punch (Fig. 38) is made of tool steel in the form of a rod, the middle part of which has a notch. The working part of the lower end of the punch is sharpened at an angle of 45-60° and hardened, and the upper end is a striker, which is hit with a hammer when punching.

Devices for marking. In order to protect the surface of the marking plate from scratches and nicks, as well as to create a stable position when marking parts that do not have a flat base, and to facilitate the marking process, cast iron linings (Fig. 39, a) and jacks (Fig. 39) are used , b) and marking boxes (Fig. 39, c) of various shapes. Squares, clamps and adjustable wedges are also used.

The marking process is carried out as follows. The surfaces of the marked workpieces are cleaned of dirt, dust and grease. Then cover with a thin layer of chalk diluted in water with the addition of linseed oil and drier or wood glue. Well-treated surfaces are sometimes coated with a solution of copper sulfate or quick-drying paints and varnishes. When the applied layer of chalk or paint has dried, you can begin marking. Marking can be done according to a drawing or template.

Rice. 37. Scale altimeter

Rice. 38. Kerner

The process of marking the workpiece according to the drawing is performed in the following sequence:
– the prepared workpiece is placed on the marking plate;
– main lines are drawn on the surface of the workpiece, from which the position of other lines or centers of holes can be determined;
– draw horizontal and vertical lines in accordance with the dimensions of the drawing, then find the centers and draw circles, arcs and inclined lines;
– small depressions are knocked out using a center punch along the marked lines, the distance between which, depending on the condition of the surface and the size of the workpiece, can be from 5 to 150 mm.

Rice. 39. Marking devices:
a - linings, b - additional frames, c - marking boxes

When marking identical parts planarly, it is more advisable to use a template. This method of marking consists in placing a steel template on the workpiece and using a scriber to trace its contours on the workpiece.

Metal cutting

Bench cutting is used to remove excess metal in cases where great processing precision is not required, as well as for rough leveling of rough surfaces, for cutting metal, cutting down rivets, for cutting out keyways, etc.

Chopping tools. The tools for cutting metal are chisels and crosscutters, and the striking tool is a hammer.

The chisel (Fig. 40, a) is made of tool steel U7A and, as an exception, U7, U8 and U8A. The width of the chisel blade is from 5 to 25 mm. The sharpening angle of the blade is selected depending on the hardness of the metal being processed. For example, for cutting cast iron and bronze, the sharpening angle should be 70°, for cutting steel 60°, for cutting brass and copper 45°, for cutting aluminum and zinc 35°. The chisel blade is sharpened on an emery wheel so that the chamfers have the same width and the same angle of inclination to the chisel axis. The sharpening angle is checked with a template or protractor.

Rice. 40. Tools for chopping metal:
a - chisel, b - crossmeisel, c - metalworker's hammer

Kreuzmeisel (Fig. 40, b) is used for cutting keyways, cutting rivets, and preliminary cutting grooves for subsequent cutting with a wide chisel.

To prevent the crossmeisel from jamming when cutting narrow grooves, its blade should be wider than the drawn part. The sharpening angles of the crossmeissel blade are the same as those of the chisel. Crossmeisel length is from 150 to 200 mm.

Bench hammer (Fig. 40, b). When chopping, hammers weighing 0.5-0.6 kg are usually used. The hammer is made from tool steel U7 and U8, and its working part is subjected to heat treatment (hardening followed by tempering). Hammers come with round and square heads. Hammer handles are made of hardwood (oak, birch, maple, etc.). The length of the handles of medium-weight hammers is from 300 to 350 mm.

To increase labor productivity in Lately began to mechanize cutting by using pneumatic hammers operating under the influence of compressed air supplied from a compressor unit.

Process manual cutting is as follows. The workpiece or part to be chopped is clamped in a vice so that the cutting marking line is at the level of the jaws. Chopping is carried out in a chair vice (Fig. 41, a) or, in extreme cases, in a heavy parallel vice (Fig. 41.6). When chopping, the chisel should be in an inclined position to the surface of the workpiece being cut at an angle of 30-35°. The hammer is struck in such a way that the center of the hammer striker hits the center of the chisel head, and you only need to look carefully at the chisel blade, which should be moved exactly along the marking line for cutting the workpiece.

Rice. 41. Vise:
a - chair, 6 - parallel

When chopping, a thick layer of metal is cut down with several passes of the chisel. To remove metal with a chisel wide surface First, the grooves are cut out with a cross-section, then the resulting protrusions are cut off with a chisel.

To facilitate work and obtain a smooth surface when cutting copper, aluminum and other viscous metals, periodically moisten the chisel blade with soapy water or oil. When cutting cast iron, bronze and other brittle metals, chipping often occurs on the edges of the workpiece. To prevent chipping, chamfers are made on the ribs before cutting.

Is the sheet material cut on an anvil or on a slab with a chisel with a rounded blade, and do I do it first? cut with light blows along the marking line, and then cut the metal with strong blows.

The main equipment of a mechanic's workplace is a workbench (Fig. 42, a, b), which is a strong, stable table with a height of 0.75 and a width of 0.85 m. The cover of the workbench must be made of boards with a thickness of at least 50 mm. The top and sides of the workbench are covered with sheet steel. A chair or heavy parallel vice is installed on the workbench. The table has drawers for storage metalworking tools, drawings and processed workpieces and parts.

Before starting work, the locksmith must check the locksmith tools. Defects found in tools are eliminated or the unusable tool is replaced with a serviceable one. It is strictly forbidden to work with a hammer with a slanted or knocked-down surface of the striker, or to use a chisel with a slanted or knocked-down head.

Rice. 42. Mechanic's workplace:
a - single workbench, b - double workbench

To protect the eyes from fragments, a mechanic must wear glasses when working. To protect others from flying fragments, a metal mesh is installed on the workbench. The workbench should be firmly placed on the floor and the vice should be firmly secured to the workbench. It is impossible to work on poorly installed workbenches, as well as on weakly secured vices, as this can lead to injury to the hand, and also quickly tires.

Metal straightening and bending

Mechanical straightening is usually used to straighten the curved shape of workpieces and parts. Straightening is performed manually or on straightening rolls, presses, sheet straightening and angle straightening machines, etc.

Straightening is done manually on a straightening cast iron plate or on a blacksmith's anvil using wood or metal hammers. Thin sheet material is straightened on correct slabs. When straightening sheet material less than 1 mm thick, wooden or steel bars are used to smooth the sheets onto the straightening plate. When straightening sheets more than 1 mm thick, wooden or metal hammers are used.

When manually editing sheet material, first identify all the bulges and mark them with chalk, then the sheet is laid on the correct plate so that the bulges are on top. After this, they begin to strike with a hammer from one edge of the sheet in the direction of the convexity, and then from the other edge. The hammer blows should not be very strong, but frequent. The hammer should be held firmly and struck on the sheet with the central part of the striker, without allowing any distortions, since if struck incorrectly, dents or other defects may appear on the sheet.

The strip material is straightened on straight slabs with hammer blows; Round bar material is straightened on a special straightening and calibrating machine.

Dents on the fenders, hood and body of the car are straightened first using shaped levers, then a blank or mandrel is installed under the dent and struck with metal or wooden hammer straighten out the dent.

Metal bending is used to obtain the required shape of products from sheet, rod, and pipe materials. Bending is carried out manually or mechanically.

When bending manually, a pre-marked metal sheet is installed in a fixture and clamped in a vice, after which the part protruding from the fixture is struck with a wooden hammer.

Pipes are bent manually or mechanically. Large pipes (for example, a muffler pipe) are usually bent with preheating at the bend points. Small pipes (pipes for power and brake systems) are bent in a cold state. In order to prevent the walls of the pipe from being flattened during bending and the cross-section not to change at the bending points, the pipe is first filled with fine dry sand, rosin or lead. To obtain a normal rounding, and at the bend point the pipe is round (without folds or dents), you need to choose the bend radius correctly (a larger pipe diameter corresponds to a larger radius). For cold bending, pipes must first be annealed. The annealing temperature depends on the pipe material. For example, copper and brass pipes are annealed at a temperature of 600-700 °C followed by cooling in water, aluminum at a temperature of 400-580 °C followed by air cooling, steel at 850-900 °C followed by air cooling.

Rice. 43. Roller pipe bending device

Pipe bending is done using various devices. In Fig. 43 shows a roller device. Mechanical bending of pipes is carried out on pipe bending, edge bending machines, and universal bending presses.

Metal cutting

When cutting metal, they use various tools: wire cutters, scissors, hacksaws, pipe cutters. The use of a particular tool depends on the material, profile and dimensions of the workpiece or part being processed. For example, to cut wire, wire cutters are used (Fig. 44a), which are made from tool steel grade U7 or U8. The cutting jaws are subjected to hardening followed by low (heating to 200° C and slow cooling) tempering.

Rice. 44. Tools for cutting metal: a - wire cutters, b - chair scissors, c - lever scissors

For cutting sheet material, hand, chair, lever, electric, pneumatic, guillotine, and disc shears are used. Thin sheet material (up to 3 mm) is usually cut with hand or chair scissors (Fig. 44, b), and thick (from 3 to 6 mm) - with lever scissors (Fig. 44, c). Such scissors are made from carbon tool steel U8, U10. The cutting edges of the scissors are hardened. The sharpening angle of the cutting edges of scissors usually does not exceed 20-30°.

When cutting with scissors, a pre-marked metal sheet is placed between the blades of the scissors so that the marking line coincides with the upper blade of the scissors.

Electric and pneumatic shears are increasingly used. The body of the electric scissors contains an electric motor (Fig. 45), the rotor of which, using a worm gear, rotates an eccentric roller, to which a connecting rod is connected, driving the movable knife. The lower stationary knife is rigidly connected to the scissors body.

Rice. 45. Electric scissors I-31

Pneumatic shears operate under the influence of compressed air.

Mechanically driven guillotine shears cut steel sheets up to 40 mm thick. Disc shears cut sheet material up to 25 mm thick along straight or curved lines.

For cutting small workpieces or parts, hand and electromechanical hacksaws are used.

A hand saw (Fig. 46) is a steel sliding frame, called a machine, in which a steel hacksaw blade is secured. The hacksaw blade has the shape of a plate up to 300 mm long, 3 to 16 mm wide and 0.65 to 0.8 mm thick. The teeth of the hacksaw blade are set in different directions so that the width of the cut formed during cutting is 0.25-0.5 mm greater than the thickness of the hacksaw blade.

Hacksaw blades come with fine and large teeth. When cutting parts with thin walls, thin-walled pipes and thin rolled products, blades with fine teeth are used, and for cutting soft metals and cast iron - with large teeth.

The hacksaw blade is installed in the machine with the teeth forward and tensioned so that it does not warp during operation. Before starting work, the workpiece or part to be cut is installed and clamped in a vice so that the marking line (cut line) is located as close as possible to the jaws of the vice.

During operation, the mechanic should hold the hacksaw by the handle with his right hand, and his left hand should rest on the front end of the machine. When moving the hacksaw away from you, a working stroke is made. During this move, you need to apply pressure, and when moving the hacksaw back, i.e., when moving towards you, an idle motion occurs, during which pressure should not be applied.

Working with a hand hacksaw is unproductive and tiring for the worker. The use of electromechanical hacksaws dramatically increases labor productivity. The structure of an electromechanical hacksaw is shown in Fig. 47. The hacksaw body contains an electric motor that rotates the shaft on which the drum is mounted.

Rice. 47. Electromechanical hacksaw

The drum has a spiral groove along which a finger fixed in the slide moves. A hacksaw blade is attached to the slide. When the electric motor operates, the drum rotates, and the hacksaw blade attached to the slide, performing a reciprocating motion, cuts the metal. The bar is designed to support the tool during operation.

Hacksaw blade.

Rice. 46. ​​Hacksaw:
1 - machine, 2 - fixed shackle, 3 - handle, 4 - hacksaw blade, 5 - magnifying glass, 6 - thumb, 7 - movable shackle

Rice. 48. Pipe cutter

A pipe cutter is used to cut pipes. It consists of a bracket (Fig. 48) with three disk cutters, of which the cutters are fixed and the cutter is movable, and a handle mounted on the thread. When working, put the pipe cutter on the pipe, turn the handle to move the movable disk until it comes into contact with the surface of the pipe, then, rotating the pipe cutter around the pipe, cut it.

Pipes and profile material They can also be cut with band saws or circular saws. The structure of the LS-80 band saw is shown in Fig. 49. On the saw bed there is a table with a slot designed for the passage (band) of the saw blade. At the bottom of the frame there is an electric motor and a driving pulley of the saw, and at the top of the frame there is a driven pulley. Using the handwheel, the saw blade is tensioned.

IN circular saws ah, instead of a cutting tape there is a cutting disk. A special feature of circular saws is the ability to cut profile metal at any angle.

Thin grinding wheels are also used for cutting hardened steel and hard alloys.

Metal filing

Filing is one of the types of metalworking, which consists in removing a layer of metal from a workpiece or part to obtain specified shapes, sizes and surface cleanliness.

This type of processing is performed with a special metalworking tool called a file. Files are made from tool steels U12, U12A, U13 or U13A, ShKh6, ShKh9, ShKh15 with mandatory hardening. According to the cross-sectional shape, files are divided into flat (Fig. 50, a), semicircular (Fig. 50.6), square (Fig. 50, c), triangular (Fig. 50, d), round (Fig. 50, e ) and etc.

According to the types of notches, files come with single and double notches (Fig. 51, a, b). Files with a single cut are used for filing soft metals (lead, aluminum, copper, babbitt, plastics), files with a double cut are used for processing hard metals. Depending on the number of notches per 1 linear line. cm, files are divided into six numbers. No. 1 includes coarsely cut files with a number of teeth from 5 to 12, the so-called “drachevye”. Files with a No. 2 cut have a number of teeth from 13 to 24, they are called “personal”. The so-called “velvet” files have a fine cut - No. 3, 4, 5, 6, and are manufactured with a number of teeth from 25 to 80.

Rice. 49. Band saw LS-80

Rice. 50. Files and their use (left):
a - flat, o - semicircular, c - square, d - triangular, d - round

For rough filing, when it is necessary to remove a layer of metal from 0.5 to 1 mm, bastard files are used, which can remove a layer of metal 0.08-0.15 mm thick in one working stroke.

In cases where, after preliminary rough filing with brute files, clean and precise processing of the workpiece or part is required, personal files are used, which can be used to remove a layer of metal 0.02-0.03 mm thick in one stroke.

Rice. 51. File notch:
a - single, b - double

Velvet files are used for the most precise processing and giving the treated surface a high purity. For finishing and other special work, files called “needles” are used. They have the smallest notch. For filing soft materials (wood, leather, horn, etc.), files called rasps are used.

The choice of file depends on the hardness of the surface being processed and the shape of the workpiece or part. To increase the service life of files, it is necessary to take measures to prevent water, oil, and dirt from getting on them. After use, the file cut should be cleaned wire brush from dirt and sawdust stuck between the teeth of the notch. For storage, files are placed in tool boxes in one row, preventing them from touching each other. To prevent the file from becoming oily during operation, rub the notch with oil or dry charcoal.

Filing techniques. The productivity and accuracy of filing depend mainly on how coordinated the movements of the right and left hands are, as well as on the force of pressure on the file and the position of the mechanic's body. When filing, the mechanic stands on the side of the vice at a distance of approximately 200 mm from the edge of the workbench so that the movement of his hands is free. The position of the mechanic's body is straight and rotated 45° relative to the longitudinal axis of the vice.

The file is taken by the handle with the right hand so that the thumb is located on top along the handle, and the remaining fingers clasp it from below. The left hand should rest with the palm across the top surface of the front end of the file.

The movement of the file must be strictly horizontal, and the force of hand pressure must be adjusted depending on the fulcrum of the file on the surface being processed. If the fulcrum is in the middle of the file, then the pressure with both hands should be the same. When moving the file forward, you need to increase the pressure of the right hand, and, on the contrary, decrease the pressure with the left. The file must move backward without pressure.

When filing, traces of file teeth, called streaks, remain on the surface being processed. The strokes, depending on the direction of movement of the file, can be longitudinal or cross. The quality of filing is determined by how evenly the strokes are spaced. To obtain a straight sawn surface, evenly covered with strokes, cross filing is used, which consists of first filing in parallel strokes from right to left, and then from left to right (Fig. 52, a).

After rough filing, check the quality of work against the light with a straight edge, which is applied along, across and diagonally to the processed plane. If the gap is the same or there is no gap at all, the quality of filing is considered good.

A more accurate method is the “paint” test, which consists of applying a thin layer of paint (usually blue or soot diluted in oil) to the surface of the test plate and placing the part with the treated surface on it, and then, lightly pressing the part, moving it it all over the slab and remove it. If traces of paint are evenly distributed over the entire surface of the part, it is considered that filing has been done correctly.

Thin round parts are filed as follows. A wooden block with a triangular cutout is clamped into a vice, into which the part to be filed is placed, and its end is clamped into a hand vise (Fig. 52, b). When filing, the hand vise, together with the part fixed in it, is gradually turned with the left hand.

When filing several planes located at an angle of 90° relative to each other, proceed as follows. First, wide opposite planes are processed by cross-filing and checked for parallelism. After this, one of the narrow planes is filed with longitudinal strokes. The quality of its processing is checked with a ruler against the light, the angles formed with a wide plane are checked with a square. Then the remaining planes are filed. Narrow planes are checked for mutual perpendicularity with a square.

When filing parts made from thin sheet metal, first, wide surfaces are processed on surface grinding machines, then the parts are combined into packs and their edges are filed using the usual techniques.

Sawing straight shaped armholes usually begins with the manufacture of liners and only after that do they begin to make armholes. First, the outer edges of the armhole are filed, then the center and contours of the armhole are marked, after marking, a round hole is drilled so that the edges of the hole are at least 1-2 mm away from the marking lines. After this, preliminary filing of the hole (armhole) is carried out and trimming is done in its corners with a needle file.

Rice. 52. Filing surfaces:
a - wide flat, b - cylindrical

Then they begin the final processing, first filing two mutually parallel sides of the armhole, after which the adjacent side is filed according to the template, and then the next opposite side, parallel to it. Mark the armhole a few hundredths of a millimeter smaller than the dimensions of the liner. When the armhole is ready, make a fitting (exact fit of the parts to each other) according to the liner.

After fitting, the liner should fit into the armhole and have no gaps in the places of contact with it.

Identical parts are made by filing using a master-conductor. The copier-conductor is a device, the contour of the working surfaces of which corresponds to the contour of the part being manufactured.

To file along a copier-conductor, the workpiece is clamped together with the copier in a vice (Fig. 53) and the parts of the workpiece protruding beyond the contour of the copier are filed. This processing method increases labor productivity when filing parts made of thin sheet material, which are clamped in a vice several at a time.

Mechanization of the filing process. At repair enterprises, manual filing is replaced by mechanized filing, performed in filing stations. machines using special devices, electric and pneumatic grinders. Lightweight portable machines include a very convenient electric Sander I-82 (Fig. 54, a) and pneumatic grinding machine ShR-06 (Fig. 54,6), on the spindle of which there is an abrasive wheel. The spindle is driven by a pneumatic rotary motor.

To file surfaces in hard-to-reach places, a mechanical file is used (Fig. 54, c), powered by an electric drive with a flexible shaft that rotates the tip /. The rotation of the tip is transmitted through the roller and worm gear to the eccentric 2. When the eccentric rotates, it imparts a reciprocating motion to the plunger 3 and the file attached to it.

Safety precautions when filing. The workpiece to be sawn must be securely clamped in a vice so that during operation it cannot change its position or jump out of the vice. Files must be with wooden handles, on which metal rings are mounted. The handles fit firmly onto the file shanks.

The shavings formed during filing are removed with a hair brush. It is strictly forbidden for a mechanic to remove chips with bare hands or blow it off, as this may cause injury to your hands and eyes.

Rice. 53. Filing according to the copier:
1 - copy bar, 2 - removable layer

Rice. 54. Tools for mechanized filing:
a - electric grinder I-82, 6 - pneumatic grinder ShR-06, c - mechanical file

When working with portable electric tools It is necessary to first check the reliability of their grounding.

Scraping

Scraping is the process of removing a very thin layer of metal from an insufficiently flat surface with a special tool - a scraper. Scraping is the final (precise) finishing of the surfaces of mating parts of machine tools, bearing shells, shafts, testing and marking plates, etc. to ensure a tight fit of the joint parts.

The scrapers are made from high-carbon tool steel U12A or U12. Often, scrapers are made from old files, removing the notch from them with an emery wheel. The cutting part of the scraper is hardened without subsequent tempering in order to give it high hardness.

The scraper is sharpened on an emery wheel so that the sharpening marks are located across the blade. To avoid excessive heating of the blade when sharpening, the scraper is periodically cooled in water. After sharpening, the scraper blade is polished on whetstones or on abrasive wheels, the surface of which is coated with machine oil.

Scrapers come with one or two cutting ends, the first are called one-sided, the second - double-sided. According to the shape of the cutting end, scrapers are divided into flat (Fig. 55, a), triangular (Fig. 55, b) and shaped.

Flat one-sided scrapers come with a straight or bent down end and are used for scraping flat surfaces of grooves and grooves. For scraping curved surfaces (when processing bushings, bearings, etc.), triangular scrapers are used.

Shaped scrapers are designed for scraping shaped surfaces, grooves, grooves, grooves, etc., with complex profiles. A shaped scraper is a set of steel plates, the shape of which corresponds to the shape of the surface being processed. The plates are mounted on a metal holder. scraper and secured to it with a nut.

The quality of surface treatment by scraping is checked on a surface plate.

Depending on the length and width of the flat surface being processed, the scraping allowance should be from 0.1 to 0.4 mm.

Before scraping, the surface of a part or workpiece is processed on metal-cutting machines or by filing.

After pre-treatment, scraping begins. The surface of the surface plate is covered with a thin layer of paint (red lead, blue or soot diluted in oil). The surface to be treated is thoroughly wiped with a rag, carefully placed on the surface plate and slowly moved along it in a circular motion, after which it is carefully removed.

As a result of this operation, all areas protruding on the surface are painted and clearly visible as spots. Painted areas (stains) along with the metal are removed with a scraper. Then the surface to be treated and the surface plate are cleaned and the plate is again coated with a layer of paint, and the workpiece or part is placed on it again.

Rice. 55. Hand scrapers:
a - straight flat one-sided and flat one-sided with a bent end, b - triangular

Newly formed stains on the surface are again removed with a scraper. During repeated operations, the spots will become smaller in size, and their number will increase. Scrape until the spots are evenly distributed over the entire surface to be treated, and their number meets the technical conditions.

When scraping curved surfaces (for example, a bearing shell), instead of a surface plate, use a shaft neck, which must be in contact with the surface of the shell being processed. In this case, the bearing shell is placed on the shaft journal, covered with a thin layer of paint, carefully rotated around it, then removed, clamped in a vice and scraped over the spots.

When scraping, the scraper is placed in relation to the surface being processed at an angle of 25-30° and held with the right hand by the handle, pressing the elbow to the body, and pressed on the scraper with the left hand. Scraping is carried out with short movements of the scraper, and if the scraper is flat and straight, then its movement should be directed forward (away from you), with a flat scraper with the end bent downwards the movement is made back (toward you), and with a triangular scraper - to the side.

At the end of each stroke (movement) of the scraper, it is torn off from the surface being processed so that burrs and ledges do not form. To obtain a smooth and precise surface to be processed, the direction of scraping is changed each time after checking the paint so that the strokes intersect.

The accuracy of scraping is determined by the number of evenly spaced spots on an area measuring 25X25 mm2 of the treated surface by placing a control frame on it. The average number of stains is determined by checking several areas of the surface being treated.

Manual scraping is very labor-intensive and therefore in large enterprises it is replaced by grinding, turning, or it is carried out by mechanized scrapers, the use of which facilitates labor and dramatically increases its productivity.

Rice. 56. Mechanized scraper

The mechanized scraper is driven by an electric motor (Fig. 56) through a flexible shaft connected at one end to the gearbox and the other to the crank. When the electric motor is turned on, the crank begins to rotate, imparting a reciprocating motion to the connecting rod and the scraper attached to it. In addition to the electric scraper, pneumatic scrapers are used.

Lapping

Lapping is one of the most accurate methods of final finishing of the processed surface, providing high processing accuracy - up to 0.001-0.002 mm. The grinding process involves removing the thinnest layers of metal using abrasive powders and special pastes. For lapping, abrasive powders from corundum, electrocorundum, silicon carbide, boron carbide, etc. are used. Lapping powders are divided into grinding powders and micropowders based on their grain size. The former are used for rough grinding, the latter for preliminary and final finishing.

For grinding the surfaces of mating parts, for example, valves to seats in engines, nipples to valve sockets, etc., GOI (State Optical Institute) pastes are mainly used. GOI pastes can be used to grind any metals, both hard and soft. These pastes are available in three types: coarse, medium and fine.

Coarse GOI paste is dark green (almost black), medium is dark green, and fine is light green. Lapping tools are made of gray fine-grained cast iron, copper, bronze, brass, and lead. The shape of the lap must match the shape of the surface being ground.

Lapping can be carried out in two ways: with and without lapping. Processing of non-mating surfaces, such as gauges, templates, squares, tiles, etc., is carried out using a lap. The mating surfaces are usually ground to each other without the use of a lap.

Lappings are movable rotating disks, rings, rods or fixed plates.

The grinding process of non-mating planes is carried out as follows. A thin layer of abrasive powder or paste is applied to the surface of the flat lap, which is then pressed into the surface with a steel bar or rolling roller.

When preparing a cylindrical lap, abrasive powder is poured into an even thin layer onto a hardened steel plate, after which the lap is rolled along the surface until the abrasive powder is pressed into its surface. The prepared lap is inserted into the workpiece and, with light pressure, is moved along its surface or, conversely, the workpiece is moved along the surface of the lap. Abrasive grains of powder, pressed into the lap, cut off a layer of metal 0.001-0.002 mm thick from the surface of the part being ground.

The workpiece must have a lapping allowance of no more than 0.01-0.02 mm. To improve the quality of lapping, lubricants are used: machine oil, gasoline, kerosene, etc.

The mating parts are lapped without lapping. A thin layer of the appropriate paste is applied to the surfaces of the parts prepared for grinding, after which the parts begin to move one over the other in a circular motion, first in one direction, then in the other.

The manual grinding process is often replaced by a mechanized one.

Automotive repair shops use rotators, electric drills and pneumatic machines to grind valves into seats.

The valve is ground to its seat as follows. The valve is installed in the guide sleeve of the cylinder block, having previously placed a weak spring and a felt ring on the valve stem, which protects the guide sleeve from getting lapping paste into it. After this, the working chamfer of the valve is lubricated with GOI paste and they begin to rotate the valve with a hand or electric drill, making one third of a turn to the left, and then two or three turns to the right. When changing the direction of rotation, it is necessary to loosen the pressure on the drill so that the valve, under the action of a spring placed on its rod, rises above the seat.

The valve is usually rubbed in first with a coarse paste, and then with a medium and fine paste. When a matte gray stripe in the form of a ring without spots is formed on the working chamfer of the valve and seat, the grinding is considered complete. After lapping, the valve and seat are thoroughly washed to remove any remaining particles of lapping paste.

Drilling is used to produce round holes in workpieces or parts. Drilling is carried out on drilling machines or with a mechanical (manual), electric or pneumatic drill. The cutting tool is a drill. Drills according to their design are divided into feather, spiral, center, drills for drilling deep holes and combined. In plumbing, twist drills are mainly used. Drills are made from tool carbon steels U10A, U12A, as well as from alloy chromium steels 9ХС, 9Х and high-speed cutting steels Р9 and Р18.

A twist drill (Fig. 57) has the shape of a cylindrical rod with a cone-shaped working end, which has two helical grooves on the sides with an inclination to the longitudinal axis of the drill of 25-30°. These grooves carry the chips out. The tail part of the drill is made cylindrical or conical. The sharpening angle at the tip of the drill can be different and depends on the material being processed. For example, for processing soft materials it should be from 80 to 90°, for steel and cast iron 116-118°, for very hard metals 130-140°.

Drilling machines. In repair shops, single-spindle vertical drilling machines are most commonly used (Fig. 58). The workpiece or part to be processed is placed on a table that can be raised and lowered using a screw. The handle secures the table to the frame at the required height. The drill is installed and secured in the spindle. The spindle is driven by an electric motor through a gearbox, and automatic feeding is carried out by a feedbox. Vertical movement of the spindle is carried out manually using a flywheel.

A hand drill (Fig. 59) consists of a spindle on which the chuck is located, a bevel gear (consisting of a large and small gear), a fixed handle, a movable handle and a breastplate. The drill is inserted into the chuck and secured. When drilling, the mechanic holds the drill with his left hand by the fixed handle, and with his right hand he rotates the movable handle, leaning his chest on the breastplate.

Rice. 57. Twist drill:
1 - working part of the drill, 2 - neck, 3 - shank, 4 - foot, l - groove, 6 - feather, 7 - guide chamfer (ribbon), 8 - rear sharpening surface, 9 - cutting edges, 10 - jumper, 11 - cutting part

Rice. 58. Single-spindle vertical drilling machine 2135

A pneumatic drill (Fig. 60, a) operates under the influence of compressed air. It is convenient to use, as it is small in size and weight.

An electric drill (Fig. 60, b) consists of an electric motor, a gear and a spindle. A chuck is screwed onto the end of the spindle, in which the drill is clamped. There are handles on the casing, and in the upper part of the body there is a breastplate for support when working.

Drilling is done either according to the markings or according to the jig. When drilling according to markings, first mark the hole, then mark it around the circumference and in the center. After this, secure the workpiece in a vice or other device and begin drilling. Drilling along the markings is usually carried out in two steps. First, drill a hole to a depth of a quarter of the diameter. If the resulting hole (not through) coincides with the marked one, then continue drilling, otherwise correct the installation of the drill and only then continue drilling. This method is most widely used.

Rice. 59. Hand drill

Rice. 60. Pneumatic (a) and electric (b) drills:
1 - rotor, 2 - stator, 3 - chuck, 4 - spindle, 5 - gearbox, 6 - trigger

Drilling a large number of identical parts with high precision is carried out using a jig (a template with precisely made holes). The jig is placed on the workpiece or part being processed and drilling is carried out through the holes in the jig. The jig does not allow the drill to deviate, so the holes are accurate and located at the required distance. When drilling a hole for a thread, it is necessary to use reference manuals to select the drill diameter in accordance with the type of thread, as well as taking into account the mechanical properties of the material being processed.

Causes of drill bit failures. The main causes of drill breakages during drilling are: deviation of the drill to the side, the presence of shells in the workpiece or part being processed, clogging of the grooves on the drill with chips, improper sharpening of the drill, poor heat treatment of the drill, dull drill.

Sharpening drills. The sharpening of the drill has a great influence on the productivity and quality of drilling. Drills are sharpened on special machines. In small workshops, drills are sharpened by hand using emery sharpeners. Control of drill sharpening is carried out with a special template having three surfaces a, b, c (Fig. 61).

Countersinking of holes is the subsequent (after drilling) processing of holes, which consists of removing burrs, chamfering and obtaining a conical or cylindrical recess at the entrance part of the hole. Countersinking is carried out with special cutting tools - countersinks. According to the shape of the cutting part, countersinks are divided into cylindrical and conical (Fig. 62, a, b). Conical countersinks are used to produce conical recesses in holes for the heads of rivets, countersunk screws and bolts. Conical countersinks can be with apex angles of 30, 60 and 120°.

Cylindrical countersinks are used to process the planes of the bosses, the recesses for the heads of screws, bolts, screws, and washers. A cylindrical countersink has a guide pin that fits into the hole being machined and provides right direction countersinks. Countersinks are made from carbon tool steels U10, U11, U12.

Countersinking is the subsequent processing of holes before deployment with a special tool - a countersink, the cutting part of which has more cutting edges than a drill.

According to the shape of the cutting part, countersinks are spiral and straight; according to their design, they are divided into solid, mounted and with inserted knives (Fig. 63, a, b, c). Depending on the number of cutting edges, countersinks come in three- and four-tooth types. Solid countersinks have three or four cutting edges, mounted countersinks have four cutting edges. Countersinking is performed on drilling machines, as well as pneumatic and electric drills. Countersinks are attached in the same way as drills.

Reaming is the finishing of a hole performed with a special cutting tool called a reamer.

When drilling a hole, leave an allowance for the diameter for rough reaming of no more than 0.2-0.3 mm, and for finishing reaming - 0.05-0.1 mm. After deployment, the hole size accuracy increases to class 2-3.

Rice. 61. Template for controlling drill sharpening

Rice. 62. Countersinks:
a - cylindrical, b - conical

According to the method of actuation, reamers are divided into machine and manual, according to the shape of the hole being machined - into cylindrical and conical, according to their design - into solid and prefabricated. Reamers are made from tool steels.

Cylindrical solid reamers come with straight or helical (spiral) teeth, and therefore the same grooves. Cylindrical reamers with a spiral tooth can have right or left grooves (Fig. 64, a, b). The reamer consists of a working part, a neck and a shank (Fig. 64, c).

Rice. 63. Countersinks:
a - solid, b - mounted, i - with insert knives

Rice. 64. Cylindrical reamers:
a - with a right helical groove, b - with a left helical groove, c - the main parts of the reamer

The cutting, or intake, part is made conical; it performs the main cutting work of removing the allowance. Each cutting edge forms a main angle in plan with the reamer axis Ф (Fig. 64, c), which for manual reamers is usually 0.5-1.5°, and for machine reamers 3-5° - for processing hard metals and 12- 15° - for processing soft and tough metals. .

The cutting edges of the fence part form an angle with the axis of the reversal at the apex of 2 cf. The end of the cutting part is chamfered at an angle of 45°. This is necessary to protect the tops of the cutting edges from nicks and chipping during operation.

The calibrating part of the reamer produces almost no cutting; it consists of two sections: a cylindrical section, which serves to calibrate the hole, the direction of the reamer, and a section with a reverse taper, designed to reduce the friction of the reamer on the surface of the hole and protect the hole from development.

The neck is the section of the reamer between the working part and the shank. The diameter of the neck is 0.5-1 mm less than the diameter of the calibrating part. Machine reamers have conical shanks, while hand reamers have square shanks. Reamers come with uniform and uneven tooth pitch. Machine reamers are secured in the machine spindle with the help of conical sleeves and cartridges, manual reamers are secured in a collar, with the help of which the reaming is carried out.

Conical reamers used for reaming conical holes for Morse taper, metric taper, and pins with a taper of 1:50. Conical reamers are made in sets of two or three pieces. A set of three scans consists of a rough, intermediate and finishing (Fig. 65, a, b, c). In a set of two reamers, one is transitional and the other is finishing. Conical reamers are made with a cutting part along the entire length of the tooth, which for finishing reamers is also a calibrating part.

Deployment by hand and on machines. Manual deployment is carried out using a crank in which the reamer is secured. When manually unfolding, small workpieces or parts are secured in a vice, while large ones are processed without securing.

After securing the workpiece or part, the cutting part of the reamer is inserted into the hole so that the axes of the reamer and the hole coincide. After this, slowly rotate the reamer clockwise; You cannot rotate the reamer in the opposite direction, as scoring may occur. When machine reaming on machines proceed in the same way as when drilling.

Rice. 65. Conical reamers:
a - rough, b - intermediate, c - finishing

When drilling holes in steel workpieces or parts, mineral oils are used as a lubricant; in copper, aluminum, brass parts - soap emulsion. In cast iron and bronze workpieces, holes are drilled dry.

The choice of reamer diameter is of great importance for obtaining the required hole size and surface cleanliness. In this case, the thickness of the chips removed by the tool is taken into account (Table 2).

Using this table, you can select the diameter of the reamer and countersink.

Example. It is necessary to manually unroll a hole with a diameter of 50 mm. To do this, take a finishing reamer with a diameter of 50 mm, and a rough reamer 50-0.07 = 49.93 mm.

When choosing a machine finishing ream, you should take into account the size of the development, i.e., the increase in the diameter of the hole during machine reaming.

When processing holes with a drill, countersink and reamer, the following basic safety rules must be observed:

perform work only on working machines that have the necessary guards;

Before starting work, put your clothes and hats in order. When working, clothing should fit the body without fluttering hems, sleeves, belts, ribbons, etc., it should be tightly buttoned.

Long hair should be matched to a headdress:
– a drill, countersink, reamer or fixture is accurately installed in the machine spindle and firmly secured;
– it is strictly prohibited to remove chips from the resulting hole with your fingers or blow them away. It is allowed to remove chips only with a hook or brush after stopping the machine or when retracting the drill;
– the workpiece or part being processed must be installed motionless on the table or plate of the machine in a fixture; you cannot hold it with your hands during processing;
– do not install the tool while the spindle is rotating or check the sharpness of the rotating drill with your hand;
– when working with an electric drill, its body must be grounded, the worker must be on an insulated floor.

Threading

Threading is the process of producing helical grooves on cylindrical and conical surfaces. The set of turns located along a helical line on a product is called a thread.

Threads can be external or internal. The main elements of any thread are profile, pitch, height, outer, middle and inner diameters.

Rice. 66. Thread elements

The thread profile is the cross-sectional shape of a thread passing through the axis of a bolt or nut (Fig. 66). A thread (turn) is the part of the thread formed during one full revolution of the profile.

The thread pitch is the distance between two points of the same name on adjacent threads, measured parallel to the axis of the thread, the axis of the bolt or nut.

Thread height is defined as the distance from the top of the thread to the base.

The apex of the thread is the section of the thread profile located at the greatest distance from the thread axis (the axis of the bolt or nut).

The base of the thread (the root) is the section of the thread profile located at the shortest distance from the thread axis.

The thread profile angle is the angle between the two flanks of the thread profile.

The outer diameter of a thread is the largest diameter measured at the top of the thread in a plane perpendicular to the axis of the thread.

Rice. 67. Thread systems:
a - metric; b - inch, c - pipe

The average thread diameter is the distance between two lines parallel to the axis of the bolt, each of which is at a different distance from the top of the thread and the bottom of the gullet. The width of the external and internal threads, measured along the circle of the average diameter, is the same.

The internal diameter of a thread is the smallest distance between opposite thread roots, measured in a direction perpendicular to the thread axis.

Profiles and thread systems. Various thread profiles are used in machine parts. The most common are triangular, trapezoidal and rectangular profiles. According to their purpose, threads are divided into fastening and special. Triangular threads are used to fasten parts together (threads on bolts, studs, nuts, etc.); they are often called fastening threads. Trapezoidal and rectangular threads are used on parts of motion transmission mechanisms (screws of metalworking disks, lead screws of screw-cutting lathes, lifts, jacks, etc.). R. There are three thread systems: metric, imperial and pipe. The main one is metric thread, which has a profile in the form of an equilateral triangle with an apex angle of 60° (Fig. 67, a). To avoid jamming during assembly, the tops of the threads of the bolts and nuts are cut off. Metric thread sizes are given in millimeters.

Pipe thread is a fine inch thread. It has the same profile as the inch one, with an apex angle of 55° (Fig. 67, c). Pipe threads are mainly used for gas, water pipes and couplings connecting these pipes.

Tools for cutting external threads. For cutting external threads, a die is used, which is a split or split ring with a thread on inner surface(Fig. 68, a, b). The chip flutes of the die serve to form cutting edges and also to release chips.

Based on their design, dies are divided into round dies, sliding dies, and special dies for cutting pipes. Round dies are either solid or split. Solid round dies have great rigidity and ensure clean threads. Split dies are used for cutting low-precision threads.

Sliding dies consist of two halves, which are called half-dies. On the outer sides of the half-dies there are grooves with an angle of 120° for securing the half-dies in the die. Each half-die is marked with a thread diameter and numbers 1 and 2, which are used as a guide when installing them in the die. Dies are made of tool steel U£2"

Manual thread cutting with dies is carried out using cranks and clamps. When working with round dies, special wrenches are used (Fig. 68, c). The frame of such a shortcut has the shape of a round die. A round die is installed in the frame hole and secured with three locking screws having conical ends that fit into special recesses on the die. The fourth screw, included in the section of the adjustable die, sets the outer thread size.

Rice. 68. Tools for cutting external threads:
a - split die, b - sliding die, c - knob, d d - die with an oblique frame

Sliding dies are installed in a die with an oblique frame (Fig. 68, d), which has two handles. Both half-dies are installed in the frame. Use an adjusting screw to bring the half dies closer together and install them to obtain a thread. the right size. A cracker is inserted between the outer half-die and the adjusting screw, ensuring uniform distribution of screw pressure on the half-dies.

Threads are cut by hand and on machines. In plumbing, hand tools are often used. Cutting external threads with sliding dies is as follows. The blank of a bolt or other part is clamped in a vice and lubricated with oil. Then a die with dies is placed on the end of the workpiece and the dies are brought together with an adjusting screw so that they cut into the workpiece by 0.2-0.5 mm.

After this, they begin to rotate the die, turning it 1-2 turns to the right, then half a turn to the left, etc. This is done until the thread is cut to the required length of the part.

Then the die is rolled along the thread to its original position, the dies are brought closer together with the adjusting screw and the cutting process is repeated until a complete thread profile is obtained. After each pass, it is necessary to lubricate the part of the workpiece being cut. Thread cutting with solid dies is done in one pass.

Rice. 69. Bench taps:
a - main parts of the tap, b - set of taps: 1 - rough, 2 - medium, 3 - finishing

Tools for cutting internal threads. Internal thread cut with a tap both on machines and by hand. In plumbing, they mainly use the manual method.

The tap (Fig. 69, a) is a steel screw with longitudinal and helical grooves that form cutting edges. The tap consists of a working part and a shank. The working part is divided into intake and calibrating parts.

The cutting part of the tap is the front conical part, which performs the main cutting work. The calibration part serves to guide the tap in the hole when cutting and calibrating threads. The teeth of the threaded part of the tap are called cutting feathers. The shank is used to secure the tap in the chuck or in the driver. The shank ends in a square. According to their purpose, taps are divided into metalworking taps, nut taps, machine taps, etc.

Taps are used for cutting threads by hand; they are produced in sets of two or three pieces. Set of taps”“’ for cutting metric and inch threads consists of three pieces: rough, medium and finishing (Fig. 69, b). The intake part of the rough tap has 6-8 turns, the middle tap has 3-4 turns, and the finishing part has 1.5-2 turns. A rough tap is used to make preliminary cuts, a medium tap is used to make the thread more accurate, and a finishing tap is used to make the final cutting and calibrate the thread.

According to the design of the cutting part, taps are cylindrical and conical. With a cylindrical design, all three taps in the set have different diameters. Only the finishing tap has a full thread profile, the outer diameter of the middle tap is less than the finishing tap by 0.6 of the thread height, and the diameter of the rough tap is less than the finishing diameter by the full height of the thread. Taps with a cylindrical cutting part are used mainly for cutting threads in blind holes.

With a tapered design, all three taps have the same diameter, full thread profile with different lengths of intake parts. These taps are used for cutting threads in through holes. Taps are made from tool carbon steels U10, U12. Threads are cut manually using a crank having a square hole.

The workpiece or part is secured in a vice, and the tap is secured in the driver. The thread cutting process is as follows. The roughing tap is installed vertically in the prepared hole and, using a wrench, begins to rotate it clockwise with light pressure. After the tap hits the metal, the pressure is stopped and rotation continues.

Periodically you need to check the position of the tap with a square in relation to the upper plane of the workpiece. The tap should be turned 1-2 turns clockwise, and then half a turn counterclockwise. This should be done for

so that the chips resulting from cutting are crushed and thereby make the work easier.

After the rough tap, cutting is done with a medium tap and then a fine tap. To obtain a clean thread and cool the tap during cutting, a lubricant is used. When cutting threads in steel workpieces, mineral oil, drying oil or emulsion are used as lubricants and coolants, in aluminum - kerosene, in copper - turpentine. In cast iron and bronze workpieces, threads are cut dry.

When cutting threads in workpieces made of soft and tough metals (babbitt, copper, aluminum), the tap is periodically unscrewed from the hole and the grooves are cleared of chips.

When working with a tap, various defects are possible, for example, breakage of the tap, torn threads, stripped threads, etc. The causes of these defects are: a dull tap, clogging of the tap grooves with chips, insufficient lubrication, incorrect installation of the tap in the hole and selection of the hole diameter, as well as inattentive attitude of the worker .

Riveting

When repairing machines and assembling them, a mechanic has to deal with various connections of parts. Depending on the assembly method, connections can be detachable or permanent. One of the ways to assemble parts into a permanent connection is riveting.

Riveting is done using rivets either manually or by machine. Riveting can be cold or hot.

The rivet is a cylindrical rod with a head at the end, which is called a rivet. In the process of riveting the rod, a second head is formed, called the closing head.

Rice. 70. Main types of rivets and rivet seams:
heads: a - semicircular, 6 - countersunk, c - semi-countersunk, d - pitch of the rivet connection; seams; d - overlap, e - butt with one overlay, g - butt with two overlays

According to the shape of the embedded head, rivets come with a semicircular head, with a semi-countersunk head, with a countersunk head (Fig. 70, a, b, c), etc.

The connection of parts made with rivets is called a rivet seam.

Depending on the location of the rivets in the seam in one, two or more rows, rivet seams are divided into single-row, double-row, and multi-row.

The distance t between the centers of rivets of one row is called the pitch of the rivet connection (Fig. 70, d). For single-row seams, the pitch should be equal to three diameters of the rivet, the distance a from the center of the rivet to the edge of the parts being riveted should be equal to 1.5 the diameter of the rivet with drilled holes and 2.5 diameters with punched holes. In double-row seams, the pitch is taken equal to four rivet diameters, the distance from the center of the rivets to the edge of the parts being riveted is 1.5 diameters, and the distance between the rows of rivets should be equal to two rivet diameters.

Riveted joints are made in three main ways: lap, butt with one overlay and butt with two overlays (Fig. 70, e, f, g). According to their purpose, rivet seams are divided into strong, dense and strong-dense.

The quality of a rivet seam largely depends on whether the rivet is selected correctly.

Equipment and tools used for manual and mechanized riveting. Manual riveting is carried out using a mechanic's hammer with a square striker, support, tension and crimping (Fig. 71). Hammers come in weights from 150 to 1000 g. The weight of the hammer is selected in accordance with the diameter of the rivet rod,

The support serves as a support for the rivet head when riveting, the tension serves to bring the riveted parts closer together, crimping is used to give correct form closing head of the rivet.

Mechanized riveting is carried out using pneumatic structures. The pneumatic riveting hammer (Fig. 72) operates under the influence of compressed air and is activated by a trigger. When you press the trigger, valve 9 opens and compressed air, flowing through the channels into the left side of the barrel chamber, activates the firing pin, which hits the crimp.

Rice. 71. Auxiliary tools used for riveting:
1 - crimping, 2 - support, 3 - tension

After the impact, the spool shuts off the flow of air into channel 3, connecting it to the atmosphere, and the compressed air is directed through channel 4 to the right side of the barrel chamber, while the striker is thrown away; channel 4 is blocked from action, etc. The pneumatic work is performed by two people , one does the riveting with a hammer, and the other is a helper.

Rice. 72. Pneumatic riveting hammer P-72

The riveting process is as follows. A rivet is inserted into the hole and installed with the mounting head on a support clamped in a vice. After this, a tension is installed on the rivet rod. The head of the tensioner is hit with a hammer, causing the parts to be riveted together to be brought together.

Then they begin to rivet the rivet rod with hammer blows, alternately delivering straight and oblique blows directly to the rod. As a result of riveting, a closing rivet head is obtained. To give the closing head the correct shape, a crimp is put on it and the final processing of the head is carried out by hitting the crimp with a hammer, giving it the correct shape.

For rivets with a countersunk head, the hole is pre-processed with a countersink to a cone. Rivet the countersunk head with straight hammer blows directed exactly along the rivet axis.

The most common riveting defects are the following: bending of the rivet rod in the hole, resulting from the fact that the diameter of the hole was very large; deflection of the material due to the fact that the hole diameter was small; displacement of the rivet head (the hole was drilled obliquely), bending of the closure head resulting from the fact that the rivet rod was very long or the support was not installed along the rivet axis; undercutting of a part (sheet) due to the fact that the crimp hole was larger than the rivet head, cracks on the rivet heads that appear when the rivet material is insufficiently ductile.

Safety precautions. When performing riveting work, it is necessary to observe following rules safety precautions: the hammer must be securely mounted on the handle; the hammer heads and crimps should not have potholes or cracks, since they can split during the riveting process and injure both the worker doing the riveting and the workers nearby with fragments; When using a pneumatic hammer, it must be adjusted. When adjusting, you should not try the hammer while holding the crimp with your hands, as this can lead to serious injury to your hand.

Pressing in and pressing out

When assembling and disassembling assemblies consisting of fixed parts, pressing and unpressing operations are used, carried out using presses and special pullers.

Pressing out is often done using screw pullers. A puller for pressing out bushings is shown in Fig. 73. It has a gripper which is pivotally connected to the end of the screw. To secure the pressed-out bushing in it, the gripper is tilted and inserted into the bushing.

Rice. 73. Puller for pressing out bushings

Pullers can be special or universal. Universal pullers can be used to press out parts of various shapes.

In auto repair shops, when disassembling and assembling cars, presses of various designs are used for pressing and pressing out: hydraulic (Fig. 74), bench rack, bench screw (Fig. 75, a, b). Bench bench rack and bench screw machines are used for pressing out bushings, pins and other small parts. The pressing and pressing of large parts is carried out using hydraulic presses.

When pressing and pressing with a hydraulic press, proceed as follows. First of all, by rotating the handle (see Fig. 74), the lifting table is installed so that the part being pressed in or pressed out freely passes under the rod, and it is secured with studs.

Rotating the flywheel, lower the rod until it stops with the part. After this, a lever is used to activate the pump, which pumps oil from the tank into the press cylinder. Under oil pressure, the piston and the rod connected to it are lowered. While moving, the rod presses (or presses out) the part. After the work is completed, the valve is opened and the piston springs upward along with the rod. The oil from the cylinder is transferred back to the reservoir.

Rice. 74. Hydraulic press:
1 - lifting table, 2 - table lifting handle, 3 - rollers for winding the cable, 4 - lifting spring, 5 - pressure gauge, 6 - cylinder, 7 - release valve, 8 - pump lever, 9 - oil tank, 10 - rod , 11 - flywheel, 12 - pressed part, 13 - bed

Rice. 75. Mechanical presses:
a - rack bench, 6 - screw bench

In all cases of pressing, to protect the surface of parts from damage and jamming, they are first cleaned of rust, scale and lubricated with oil. There should be no nicks, scratches or burrs on parts prepared for pressing.

Soldering

Soldering is a method of joining metal parts to each other using special alloys called solders. The soldering process consists of placing the parts to be soldered one next to the other, heating them to a temperature slightly higher than the melting point of the solder, and liquid molten solder is introduced between them.

To obtain a high-quality solder joint, the surfaces of the parts are cleaned of oxides, grease and dirt immediately before soldering, since the molten solder does not wet contaminated areas and does not spread over them. Cleaning is carried out mechanically and chemically.

The surfaces to be soldered are first subjected to mechanical cleaning from dirt, rust with a file or scraper, then degrease them by washing them in a 10% solution of caustic soda or in acetone, gasoline, denatured alcohol.

After degreasing, the parts are washed in a bath of running water and then etched. Brass parts are etched in a bath containing 10% sulfuric acid and 5% chromium; for etching steel parts, a 5-7% solution of hydrochloric acid is used. At a solution temperature of no more than 40°C, parts d are kept in it for 20 to 60 minutes. ~~ At the end of etching, the parts are thoroughly washed, first in cold, then in hot water.

Before soldering, the working part of the soldering iron is cleaned with a file and then tinned (coated with a layer of tin).

When soldering, tin-lead and copper-zinc are most commonly used. copper, silver and copper-phosphorus solders.

To eliminate the harmful effects of oxides, fluxes are used, which fuse and remove oxides from the surfaces being soldered and protect them from oxidation during the soldering process. The flux is selected in accordance with the properties of the metals being soldered and the solders used.

Solders are divided into soft and hard. Soft solders are used to solder steel and copper alloys. Steel parts before soldering soft solders served. Only under this condition can a reliable solder connection be ensured.

The most common soft solders are tin-lead alloys of the following grades: POS-EO, POS-40, POS-ZO, POS-18. Solders are available in the form of rods, wires, strips and tubes. As fluxes for soft soldering, zinc chloride, ammonium chloride (ammonia), rosin (for soldering copper and its alloys), 10% aqueous solution of hydrochloric acid (for soldering zinc and galvanized products), stearin (for soldering low-melting alloys) are used. lead).

For soldering critical parts made of cast iron, steel, copper alloys, aluminum and its alloys, hard solders are used, mainly copper-zinc and silver of the following grades: PMC-36, PMC-48, PMC-54, PSr12, PSr25, PSr45 (melting temperature of hard alloys from 720 to 880 °C).

For soldering aluminum and its alloys, for example, solder of the following composition is used: 17% tin, 23% zinc and 60% aluminum. Borax, boric acid and their mixtures are used as fluxes. When soldering aluminum, they use a flux consisting of a 30% solution of an alcohol mixture, which contains 90% zinc chloride, 2% sodium fluoride, 8% aluminum chloride.

When soldering with hard solders, the parts are fixed in special devices in such a way that the gap between the parts does not exceed 0.3 mm. Then flux and solder are applied to the area to be soldered, and the part is heated to a temperature slightly above the melting point of the solder. The melted solder fills the gap and forms a strong connection as it cools.

After soldering is completed, the parts are cleaned of flux residues, since remaining fluxes can cause corrosion of the weld surface. The seams are cleaned with a file or scraper.

The main tools for soldering are soldering irons and blowtorches. In addition, when soldering, induction heating installations with high frequency currents and other devices are used. When soldering with soft solders, soldering irons (Fig. 76, a, b, c) and blowtorches are usually used.

A hand-held soldering iron is made of copper and may have different shapes(Fig. 76, a, b). When brazing, the parts to be soldered are heated with a blowtorch or in a forge.

TO Category: - Car maintenance