Marking is the operation of applying marking marks to the surface of a part or workpiece to be processed, defining the contours of the part profile and the places to be processed. The main purpose of marking is to indicate the boundaries to which the workpiece must be processed. To save time, simple workpieces are often processed without preliminary marking. For example, in order for a toolmaker to make an ordinary key with flat ends, it is enough to cut off a piece of square steel from a bar of a certain size, and then saw it to the dimensions indicated on the drawing.
Blanks are received for processing in the form of castings (produced from metal poured into pre-prepared molds - earthen, metal, etc.), forgings (produced by forging or stamping), or in the form of rolled material - sheets, rods, etc. d. (obtained by passing metal between rotating different sides rollers having a profile corresponding to the resulting rolled product). If there are holes in the workpieces, then to mark their centers, a wooden or aluminum plate is tightly driven into the hole
When manufacturing a part, its dimensions are laid down on the workpiece exactly according to the drawing and marked with lines (marks) indicating the processing boundaries to which the metal layer should be removed. Marking is used mainly in single and small-scale production. In large-scale and mass production factories, the need for markings is eliminated due to the use of special jigs, stops, etc.
Three main groups of markings are used: mechanical engineering, boiler room and ship. Mechanical marking is the most common metalworking operation. The boiler room and ship markings have some peculiarities. Depending on the shape of the blanks and parts being marked, marking can be planar and spatial (volumetric).
Planar marking is the application of flat workpieces on sheet and strip metal, as well as on the surfaces of cast and forged parts of various lines. When marking in space, marking lines are applied in several planes or on several surfaces.
Apply various ways markings: according to drawing, template, sample and location. The choice of marking method is determined by the shape of the workpiece, the required accuracy and the number of products. The accuracy of marking significantly affects the quality of processing. The degree of marking accuracy ranges from 0.25--0.5 mm. Errors made during marking lead to defects.
At machine-building and instrument-making plants, marking is carried out by workers qualified as markers, but often this operation has to be performed by a toolmaker.
At the workplace of a marker or tool maker there should be various marking, control and marking tools and devices. One of these devices is a precise control and marking plate, on which parts are installed and all fixtures and tools are prepared.
Marking plates are cast from gray fine-grained cast iron; in the lower part the plate has stiffening ribs that protect the plate from possible deflection. The top, working surface and sides of the slab are precisely processed planing machines and scraping. On work surface Large slabs are sometimes made with longitudinal and transverse grooves 2-3 mm deep and 1-2 mm wide at equal distances (200-250 mm), forming equal squares. The grooves make it easier to install various devices on the plate.
"The dimensions of the slab are chosen so that its width and length are 500 mm more sizes marked workpiece.
Marking tools include: scriber (with one point, with a ring, double-sided with a curved end), marker (there are several types), marking compass, punches (regular, automatic, for stencil, for circle), calipers with a conical mandrel, hammer , center compass, rectangle, marker with prism. 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 strubs, 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 crown compass, a level, a control ruler for surfaces, a feeler gauge and standard tiles.
TO auxiliary materials for markings include: chalk, White paint(a mixture of chalk diluted in water with linseed oil and adding a compound that prevents the oil from drying out), red paint (a mixture of shellac with alcohol and the addition of dye), lubricant, washing and etching materials, wooden blocks and slats, small tin containers for paints and a brush.
(tools and devices)
The purpose of the marking is to outline and apply the contours of the future part on the workpiece so that, during the processing of the workpiece, this very part of the required size and quality is obtained with a minimum amount of waste. Marking is done using marking tools, such as: malka, level, compass, bore gauge, drawbar, bracket, surface planer, level with plumb line, center finder square, tape measure, square, tape measure, erank, folding meter. With the help of these tools, they determine, measure, calibrate and mark thin lines, bends, angles for cutting, drilling, chiselling and planing, taking into account the type of wood, as well as taking into account allowances (margin) for further processing. Let's get acquainted with the structure and operating principles of these tools.
Malka - angular template with variable measurement angle. Represents rectangular section a block (block), one end of which is sawn at an angle of 45°, and at the other end, half the length, a through slot is made, through which a ruler is hingedly attached with a bolt with a wing nut screwed onto it. Due to this slot, the ruler can move along the block in cases where it is necessary for reasons of difficult accessibility of applying the fry to the workpiece in the right place.
Compass - a drawing tool designed for transferring dimensions from a sketch (drawing, diagram, template) to the plane of workpieces, as well as for outlining circular markings of the required dimensions.
Bore gauge - in principle, the same compass (meter) with two needles curved in directions opposite to each other. Purpose - transfer of internal measurements of holes, grooves, notches, etc.
Otvoloka - a tool designed for marking in the form of scratches on the edge of a board, is a wooden block 400 mm long and 50 mm wide. One end of the block is somewhat beveled and at a distance of 1/5 from the edge has a protrusion in which there is a movable but fairly tightly fixed scriber (sharp pin, needle, nail). The remaining 4/5 of the bars are 5-7 mm thinner for ease of working with the scriber.
Bracket - a tool designed for marking when manually cutting tenons and eyes. The tool is made in the form wooden block, having at a distance of 1/3 from the edge a sample the size of a quarter in which nails are hammered, the distances between the points of which are equal to the thickness of the tenons (eyes). Marking is done by drawing cut lines with nails in the parts of the joint with a tenon joint.
Reismus - a tool used to apply marks running parallel to one of the sides of the workpiece. It consists of a wooden block approximately 30x60x90 mm, into which two bars are inserted through two holes made in its body, at the ends of which on one side there are sharp pins (needles, nails) for applying marks. The depth of extension of the bars is fixed with a locking wedge. The transfer size is measured from the edge of the block to the tip of the sliding bar, or between two tips.
Plumb level - an instrument made in the form of an isosceles right triangle, the base of which is the hypotenuse with a mark applied in its middle. From the top right angle A plumb line is dropped onto the hypotenuse. If the base is horizontal, the plumb line points to the mark; if horizontality is violated, the plumb line deviates in one direction or another. Thus, the verticality of articulated and free-standing parts is checked.
Corner finder is a rectangular isosceles square made of bars with a cross-section of 30x15 mm with a ruler tightly fixed to it at the joint of the corner. The ruler is installed so that the working, digitized and marked side divides the right angle of the triangle in half. At the same distance from the top of the angle, both rays of the square are connected by a “string” (a block of the same cross-section) placed on top of the rays and the ruler. In this case, the ruler is completely recessed from below in the groove of the “string”, equal in depth to the thickness of the ruler. If you now put the square on the end round lumber So; so that the ruler lies on the plane of the end, and the rays are pressed against the side surface, and draw two intersecting lines along the ruler, moving the square along the side surface of the round timber, without tearing the rays and ruler off the material, at the point of intersection of these straight lines we obtain the desired center of the section of the round timber.
Square - a tool designed to check and establish the squareness of construction blanks, as well as to mark perpendicular cuts. The structure of the square is simple: a block with a cross-section of 20x30 mm, into the end of which a ruler with a cross-section of 5x30 mm with divisions is embedded at a right angle. The significant difference in the thickness of the block and the ruler allows you to use the square in the same way as when working with a surface thicknesser.
Tools For markings
a - malka; b - compass, c - bore gauge, d - drawbar, d - bracket, e - thickness gauge, g - square, h - center finder square, i - weight level, k - folding meter, l - tape measure, m -erunok
Meter tape has the same purpose as a roulette, but allows for more precise measurements, since it has not only centimeter, but also millimeter divisions. These roulettes are sometimes not hidden in a blind box, but tucked into a box that is open on one side, but equipped with special device allowing it to be folded and placed in a box. By the way, the tape of such tape measures, thanks to their special production, when leaving the box retains the appearance of light, straight, grooved in longitudinal direction rulers.
Erunok - a tool similar to a crowbar, only with a ruler rigidly attached to the block at an angle of 45°. This way you can quickly measure and mark angles of 45 and 135°.
Folding meter - a tool (metal or wood) used for measuring workpieces and finished products short length. It is a set of rulers of the same length (100 or 200 mm), hinged and softly locked in working and folded states.
Marking is the operation of applying marking lines to the workpiece being processed, defining the contours of the future part or place to be processed.
The accuracy achieved with conventional marking methods is approximately 0.5 mm.
Planar marking, usually performed on the surface of flat parts, on strip and sheet material, consists of applying contour parallel and perpendicular lines (marks), circles, arcs, angles, center lines, and various geometric shapes according to specified dimensions or contours various holes according to templates.
Spatial marking is most common in mechanical engineering; and in its techniques it differs from the planar one.
Devices for planar marking
To carry out markings, marking plates, pads, rotating devices, jacks, etc. are used.
The parts to be marked are installed on the marking plate and all fixtures and tools are placed. The marking plate is cast from fine-grained gray cast iron.
The size of the slab is chosen so that its width and length are 500 mm greater than the corresponding dimensions of the workpiece to be marked. The surface of the stove must always be dry and clean. After work, the slab is swept with a brush, thoroughly wiped with a rag, greased with oil to protect against corrosion and covered with a wooden shield.
Tools for planar marking
Scribler, caliper, center punch, ruler, square, hammer, etc.
Scribblers are used to draw lines (scores) on the surface to be marked using a ruler, square or template. Scribblers are made from tool steel U10 or U12, sharpened to a cone at an angle of 15-20 0.
Kerner - a metalworking tool used for making indentations (cores) on pre-marked lines.
Cores are made from tool carbon or alloy steel U7A, U8A, 7HF or 8HF, at an angle of 50-60 degrees.
Compasses used for marking circles and arcs, dividing segments and circles, as well as for geometric constructions. Compasses are also used to transfer dimensions from measuring rulers for detail.
Reismas is the main tool for spatial marking and is used for applying parallel, vertical and horizontal lines, as well as to check the installation of parts on the plate.
Preparing for marking.
Before marking, you must do the following:
Clean the workpiece from dust, dirt, scale, traces of corrosion with a steel brush, etc.;
Carefully inspect the workpiece;
If shells, bubbles, cracks, etc. are detected, measure them accurately and, drawing up a marking plan, take measures to remove these defects during further processing (if possible);
All dimensions of the workpiece must be carefully calculated so that after processing there are no defects left on the surface;
Study the drawing of the part to be marked, find out its features and purpose;
Specify dimensions;
Define base surfaces blanks from which dimensions should be taken during the marking process;
When planar marking, the bases can be the processed edges of the workpiece or the center lines, which are applied first;
It is also convenient to take tides, bosses, and plates as bases.
Applying marking marks. Marking marks are applied in the following sequence: first, horizontal ones are made, then vertical ones, after that - inclined ones, and lastly - circles, arcs and roundings.
Direct marks are applied with a scriber, which should be tilted in the direction of its movement and away from the ruler. The scriber is constantly pressed against the ruler, which should fit tightly to the part. Risks are carried out only once. If the mark is applied poorly, paint over it, let the dye dry, and apply the mark again.
Angles and slopes are marked using protractors, calipers, and inclinometers.
Marking marking lines. A core is a depression (hole) formed by the action of the tip of a center punch when it is struck with a hammer. The centers of the punches must be located exactly on the marking lines.
Marking hammers. For marking works use hammer No. 1 (weighing 200 g).
Marking methods. Template marking is usually used in the production of large batches of parts of the same shape and size, but sometimes even small batches of complex products are marked using this method.
Marking with a pencil It is produced on a line on blanks made of aluminum and duralumin. It is not allowed to mark the latter using a scriber, since the marks are destroyed when applied. protective layer and traces of corrosion appear.
Defects:
Inconsistency between the dimensions of the marked workpiece and the drawing data due to the inattention of the marker or the inaccuracy of the marking tool;
Inaccuracy of setting the gauge on right size; the reason for this is the inattention or inexperience of the marker, the dirty surface of the slab or workpiece;
Careless installation of the workpiece on the slab as a result of slab alignment.
Safety.
Observe following rules occupational safety:
Installing workpieces (parts) on the stove and removing them from the stove must be done only with gloves;
Workpieces (parts) and fixtures should be securely installed closer to the middle;
Before installing workpieces (parts), check the slab for stability;
Check the reliability of the hammer on the handle;
Remove dust and scale from the marking plate only with a brush, and from large plates - with a broom.
Marking is the application of points and lines to the materials to be processed or to the product being processed, indicating the axes and contours of the part according to the drawing, as well as the places to be processed.
The main purpose of marking is to indicate the boundaries to which the workpiece must be processed. The difference between the dimensions of the workpiece before and after processing is called processing allowance. However, in order to save time, simple workpieces are often processed without preliminary marking (for example, they are filed to the dimensions indicated in the drawing).
Sometimes two marks are applied: one to indicate the processing boundary, the other at some distance from it - for control.
There are planar and spatial markings. By using planar marking mark flat parts or individual planes of parts if they should not be linked to their other planes. Planar marking techniques are very similar to technical drawing techniques and are performed with tools similar to drafting ones.
Spatial marking consists in marking individual surfaces of a part located in different planes and under different angles to each other, are linked to each other. For spatial marking, the part is installed on a special marking plate, and the correctness of its installation is carefully checked.
When marking, the following tools are used (Fig. 4.2): rulers, meter, scriber, center punch, steel square, protractor, marking compass, caliper, surface planer, etc.
Rice. 4.2. Tools used for marking: a - scriber; b - mechanic's square; c - marking compass; g - surface planer; d - caliper.
Part marking can be done according to a drawing or a template.
Marking according to a drawing requires certain skills from the worker: a clear understanding of the drawing or sketch, the right choice the base from which the dimensions of the part are plotted, accurately setting the dimensions using a scale ruler and transferring them to the part to be marked.
Templates are usually used in markup large quantity flat parts and can significantly simplify and speed up the marking process itself. Templates are made from sheet steel, aluminum alloys or plywood. To mark a part using this method, the template is placed on the sheet to be marked, pressed against it and traced along the edges using a scriber. In this case, it is necessary to hold the scriber at a constant angle to the sheet, without tilting it towards the template (or ruler), since this distorts the dimensions of the part.
Usually, when drawing marks, the scriber is held with a double slope: one at 15-20° from the vertical away from the ruler (or template), the other in the direction of the scriber’s movement so that the angle between it and the workpiece (part) is 45-70°.
The mark should be carried out only once, and in order for it to be as thin as possible, the tip of the scribe should always be well sharpened.
To ensure that the lines drawn during marking are not erased during transportation and processing of the part, they are punched after 50-100 mm, and on curves - after 5-10 mm. The center punch is placed at the marked point first obliquely, and at the moment of impact it is brought to a vertical position (Fig. 4.3). The fingers of the hand holding the center punch should not touch the part being marked. The hammer strike is easy to apply.
Rice. 4.3. Punching techniques.
Nailing should be done after all marking is completed. It should be remembered that marking is one of the most critical operations that ensure correct production details. Therefore, the worker, when marking, must be careful, especially when determining the dimensions from the drawing, applying them to the workpiece, and also when installing the part on the marking plate. Marking should only be done with a serviceable and accurate tool.
TO category:
Marking
Tools and devices used for marking in plumbing
Marking is done using various instruments and devices, which include a scriber, a compass, a thickness gauge, a height gauge, a scale altimeter, squares, center-finder squares, center punches, a bell, a hammer, a marking plate,
The scriber is used to draw lines (scores) on the marked surface using a ruler, square or template. When applying marks, the scriber is held in the hand like a pencil, pressing it tightly against the ruler or template and tilting it slightly in the direction of movement so that it does not tremble. The scriber is carried out only once, then it turns out clean and correct. Methods of using the scriber are shown in Fig. 1.
Rice. 1. Scribbler and its application: a - scriber, b - two positions of the scriber when drawing marks: correct (left) and incorrect (right), c - drawing marks with the curved end of the scriber
The scriber is made from carbon tool steel U10-U12. Its ends at a length of about 20 mm are hardened. The scriber is sharpened on sharpening machine, while holding it with the left hand by the middle, and with the right hand by the unsharpened end. Applying the tip of the scriber to the rotating stone, rotate it evenly with the fingers of both hands around the longitudinal axis.
The compass is used to transfer linear dimensions from a scale ruler to the workpiece, dividing lines into equal parts, constructing angles, marking circles and curves, to measure the distances between two points, followed by determining the size using a scale ruler.
There are simple marking compasses (Fig. 2, a) and spring ones (Fig. 2, b). A simple compass consists of two hinged legs, solid or with inserted needles. To secure the open legs in the required position, an arch is attached to one of them
Rice. 2. Compasses: a - simple, b - spring
In a spring compass, the legs are connected by a spring ring. The legs are moved apart and brought together by rotating the split nut in one direction or the other along the set screw.
The legs of the compass are made of steel grades 45 and 50. The ends of the working parts of the legs are hardened at a length of about 20 mm.
The thicknesser is used to draw parallel, vertical and horizontal lines, as well as to check the installation of parts on the plate. The thicknesser consists of a cast iron base, a stand and a scriber. The scriber can be mounted anywhere on the stand, rotated around its axis and tilted at any angle. In Fig. Figure 3b shows different types of surface planers and how to use them.
Rice. 3. Thicknesser and its application: a - general view of the thicknesser: 1 - base, 2 - stand, 3 - scriber needle, 4 - set screw for adjusting the needle for precise size adjustment, 5 - stop pins; b - some techniques for using a thicknesser: 1 - making parallel marks (the stop pins of the thicknesser are lowered down with springs, and the thicknesser rests against the edge of the tile being marked), 2 and 3 - applying marks at different positions of the thicknesser needle, 4 and 5 - making circular marks on disks; c - thicknessers for marking sheet material: 1 - sliding thicknesser with precise adjustment to size, 2 - plate for applying marks from the edge of the sheet at one certain distance from it, 3 - slotted sliding thicknesser with size adjustment using a scale ruler
Scale altimeter. In addition to the previously described scale ruler, which is used to determine linear dimensions and draw straight lines on the surface of the workpieces to be marked, a scale altimeter is used to measure distances and plot vertical dimensions.
Marking calipers are intended for drawing circles of large diameters. It consists of a rod with millimeter graduations and two legs - fixed and movable with a vernier. The legs, secured in the required position with locking screws, have insertable needles that can be placed higher or lower, which is very convenient when describing a circle at different levels.
Rice. 4. Scale altimeter (next to the thickness gauge)
Rice. 5. Marking caliper with insert needles: 1 - fixed leg, 2 - rod, 3 - locking screw for securing the frame, 4 - frame with vernier, 5 - hundred. stop screw for fastening the insertion needle, 6 - movable leg, 7 - insertion needles
In Fig. Figure 6 shows a different type of marking caliper for more accurate marking of straight lines and centers and shows examples of its use.
A height gauge is used to check heights and more accurately apply center and other marking lines to the surfaces being processed.
Squares are used for drawing vertical and horizontal lines on marked surfaces, checking the correct installation of parts on the plate, as well as for marking sheet and strip material; center-finder squares are used for applying marks passing through the center on the ends of round products. The center finder square (Fig. 30) consists of two strips connected at an angle; The working edge of the ruler passes through the middle of the corner. The connecting strip serves to provide rigidity to the device. When marking centers, the part to be marked is placed on its end. A square is placed on the upper end so that the planks connected at an angle touch the part. Draw a line along the ruler using a scribe. Then turn the part or square approximately 90° and make a second mark. The intersection of the marks determines the center of the end of the part.
Rice. 6. Vernier calipers for accurately marking straight lines and centers (a) and its application (b)
Rice. 7. Height gauge: 1 - rod, 2 - frame clamp, 3 - frame, 4 - base, 5 - leg for measuring yaw, 6 - vernier, 7 - micrometric frame feed, 8 - leg for marking
Rice. 8. Marking square and its application. a - square with a shelf, b - installation of the square when drawing (or checking) vertical lines, c - position of the square when drawing lines in the horizontal plane
The center punch is used to make small indentations on the marks. This tool is a round rod with a knurl in the middle part, at one end of which there is a conical tip with an angle at the needle of 45-60°; the other end of the center punch is pulled to a cone; This end is struck with a hammer when punching.
Rice. 9. Square finder
Rice. 10. Kerner
The punches are made from carbon tool steel U7A. Their working part (edge) is hardened at a length of about 20 mm, and the striking part at a length of about 15 mm.
The tip of the punch is sharpened on a grinding machine, securing the punch in the chuck; Under no circumstances should you hold the center punch in your hands while sharpening.
When punching, the punch is taken with three fingers of the left hand - thumb, index and middle, as shown in Fig. 32. The point of the center punch is set exactly at the middle of the marks or at the intersection point of the marks. Before the impact, tilt the center punch slightly away from you in order to position it more accurately, and at the moment of impact, without moving the punch from the mark, place it vertically. The hammer strike is easy to apply.
The hammer for striking the center punch should be light in weight, approximately 50-100 g.
A bell is a special device that is easy and convenient for marking the center and punching center holes at the ends of round parts. The device is placed on the end of the part with a conical hole; in this case, the bell center punch is automatically installed in the center of the end of the part. With a light blow of a hammer on the center punch, the center is marked.
Rice. 11. Punching: a - installation of the punch at the mark, b - position of the punch when hit with a hammer, c - marked and punched part before processing (top) and after processing (bottom)
Rice. 12. Bell for piercing centers
Rice. 13. Spring center punch
The spring center punch has a body screwed together in three parts. The housing contains two springs, a rod with a center punch, a striker with a sliding block and a flat spring. When punching, that is, when pressing on the product with the tip of the punch, the inner end of the rod rests against the cracker, as a result of which the striker moves upward and compresses the spring. Resting against the edge of the shoulder, a cracker
moves to the side, and its edge comes off the rod. At this moment, the striker, under the influence of the force of a compressed spring, delivers a strong blow to the end of the rod with the center punch. Immediately after this, the spring restores the initial position of the center punch.
An electric punch consists of a housing, springs, a striker, a coil with a varnished wire winding, and a punch. When you press the tip of the punch installed on the mark, the electrical circuit is closed and the current passing through the coil creates a magnetic field, the striker is instantly drawn into the coil and strikes the punch rod. During the transfer of the punch to another point, the spring opens the circuit, and the spring returns the hammer to its original position.
Rice. 14. Electric punch
Rice. 15. Marking plate on the table
The marking plate is the main device for marking. It is a cast iron plate with a precisely machined top surface and sides. The product to be marked is installed on the plane of the slab and markings are made. The surface of the marking plate should be protected from damage and impact. After marking is completed, the slab is wiped with a dry, clean rag or washed with kerosene and lubricated with oil, then covered with a protective wooden shield.
When marking, various devices are used in the form of pads, prisms, and cubes.
Main stages of marking
Before marking, the workpiece is carefully inspected, checking whether it has any defects - holes, bubbles, cracks, films, distortions, whether its dimensions are correct, whether the allowances are sufficient. After this, the surface intended for marking is cleaned of scale and molding soil residues and irregularities (bumps, burrs) are removed from it, then painting begins
The workpiece is painted so that the marking lines are clearly visible during processing. Black, i.e. untreated, as well as roughly processed surfaces are painted with chalk, quick-drying paints or varnishes. Chalk (powder) is diluted in water to the consistency of milk and a little linseed oil and drier are added to the resulting mass. It is not recommended to rub the surface to be marked with a piece of chalk, as the chalk quickly crumbles and the marking lines disappear.
To paint cleanly treated surfaces, copper sulfate is used - in solution or in pieces. A solution of copper sulfate (two to three teaspoons per glass of water) is applied to the surface with a brush or cloth; Rub lump vitriol on surfaces moistened with water. In both cases, the surface is covered with a thin and durable copper layer, on which the marking lines are clearly visible.
Before applying marking marks to the painted surface, determine the base from which the marks will be applied. For planar marking, the bases can be the outer edges of flat parts, strip and sheet material, as well as various lines applied to the surface, for example, center, middle, horizontal, vertical or inclined. If the base is the outer edge (bottom, top or side), then it must first be aligned.
The marks are usually applied in the following order: first, all horizontal marks are drawn, then vertical ones, then inclined ones and, finally, circles, arcs and roundings.
Since the marks can be easily rubbed out with your hands during work and they will then become difficult to see, small depressions are filled along the lines of the marks with a center punch. These recesses - cores should be shallow and divided in half by a line.
The distances between the punches are determined by eye. On long lines of simple outline, these distances are taken from 20 to 100 mm; on short lines, as well as in corners, bends or curves - from 5 to 10 mm.
On the processed surfaces of precision products, marking lines are not punched.
