Purpose, types, essence, techniques and sequence of execution

Fitting operations of metalwork processing include: fitting, fitting, grinding and finishing.

For fit one part to another, first of all, it is necessary that one of the parts be completely finished - and fitting is carried out on it. In fitting sliding parts, the most significant obstacle is the sharp edges and corners of the surfaces to be cut. They are adjusted until the mating parts enter one another freely, without a gap. If the connection is not visible through the light, sawing along the paint is carried out. On the adjusted surfaces, traces of friction from one surface to another can be discernible even without paint. These traces, which look like shiny spots, show that it is these places that prevent the movement of one part over another. Shiny places (or traces of paint) are filed with a file until the part is finally ready. During any fitting work, sharp edges and burrs should not be left on the parts; they need to be smoothed with a file, as they can get hurt. The quality of the processing of the ends and edges can be judged by running your finger over them.

The concept of edge smoothing should not be confused with the concept of chamfering. When chamfering on the edge of the part, a small flat ribbon is made, inclined at an angle of 45 ° to the side faces of the part.

Fitting called the mutual fitting of parts mating without a gap. Fit both closed and semi-closed contours. Fitting is characterized by high processing accuracy. In fitting parts, the hole is called an armhole, and the part included in the armhole is called an insert. Templates, counter-templates, stamping tools (punches and dies), etc. are subjected to fitting. The working parts of the template and counter-template must be fitted, so that when the fitted sides of the template and counter-template come into contact, there is no gap between these sides for any of options mutual permutations of the pattern and the counter-pattern.

Lapping- surface treatment of the product with lapping, which is a tool made of soft materials with grinding powder. With the help of a lap, the thinnest layer of metal (up to 0.02 mm) is removed from the workpiece. The thickness of the metal layer removed by lapping in one pass does not exceed 0.002 mm. Lapping is done after work with a file or scraper for final finishing surface of the workpiece and give it the greatest accuracy. Lapping is a very precise finishing operation and is used to provide tight, airtight detachable and movable joints (connection of tap parts, valves, which retains liquids and gases well). The accuracy of grinding parts is made from 0.001 to 0.002 mm or until the mating surfaces completely match. The allowance for this operation is 0.01-0.02 mm. Lapping is done on the stovetop. Electrocorundum, emery (aluminum oxide), silicon carbide, crocus (iron oxide), chromium oxide, Viennese lime, tripoli, crushed glass, diamond dust, GOI pastes and other materials are used as an abrasive. Of the lubricants, the most commonly used machine oil, kerosene, gasoline, toluene, alcohol.

To lap the part, an abrasive powder mixed with oil is applied to the lapping plate in a thin, uniform layer. The part is placed with a lapped surface on the plate and moved in a circular motion over the entire plate until a matte or glossy (shiny) surface is obtained.

During the lapping process, the mechanical removal of metal particles is combined with chemical reactions. When working with abrasive substances, the treated surface is oxidized under the action of the abrasive and atmospheric oxygen. With the movement of the lap, this film of oxidized metal is removed from the surface, but the surface immediately oxidizes again. In this way, the metal is removed until the surface acquires the required accuracy and cleanliness of processing.

debugging performed on pre-polished surfaces, with a finishing allowance of 0.01 to 0.02 mm left. Finishing is a type of lapping and serves to obtain not only the required shapes and surface roughness, but also the specified dimensions of parts with high precision. Finished surfaces are more durable, which is a determining factor for measuring and verification tools and very precise workpieces.

Working tool and accessories

An important condition for high-quality machining of aligned surfaces and holes is right choice files. Files are selected according to the section profile depending on the shape of the surfaces and holes being processed: for recesses and holes with a square section - square files, for rectangular ones - flat and square files, for triangular ones - trihedral, diamond-shaped and semicircular, for hexagonal holes - trihedral and square . Files should have a width of the working part of not more than 0.6-0.7 of the size of the side of the recess or hole, the length of the file is determined by the size of the surface to be processed (along the length) plus 200 mm. When machining curved surfaces of holes in the form of radius, oval or complex curvilinear contours round or semicircular files are used, in which the radius of curvature must be less than the radius of curvature of the contour being machined. Fitting is done with files with fine and very fine notches - No. 2, 3, 4 and 5, as well as abrasive powders and pastes.

It also contributes to high-quality processing of parts correct selection clamping devices, such as a hand vise, allowing you to quickly clamp the workpiece. Their design allows the workpiece to be clamped in a vice with a cone device that opens and closes the jaws when the round handle with a knurled surface is rotated. Oblique vise jaws are used for clamping parts when filing inclined surfaces and chamfering. Oblique jaws are inserted between the jaws of conventional parallel bench vise.

A curved vise is used to perform operations that require high basing accuracy and reliable fastening of a part (during marking, drilling, reaming, flat and profile grinding). These vices differ from machine vices in their high manufacturing precision and the possibility of their installation on three mutually perpendicular planes. The fixed jaw is integral with the body. The design of the movable jaw allows it to move along the precisely ground plane of the body. In this case, the direction of the lips is given by two keys. The movable jaw is held on the plane of the housing by screws that pass through the distance stop and the bar.

The distance stop, when the screws are tightened, allows the parts to move in a sliding fit relative to the housing rails. The movement of the sponge is carried out with the help of a screw rotating in a nut, which is fixedly fixed on the body and locked in the movable sponge with a pin. Side surfaces curved vise are strictly perpendicular to the ground base and parallel to each other, and the clamping planes of the jaws are perpendicular to the base and the upper plane of the vise body. All main parts of the vise are made of U7A steel, subjected to heat treatment to HRC 55-58 hardness and grinding with tolerances for the second accuracy class. Clamps are widely used in fitting operations performed by a locksmith. For example, a clamp with a differential clamping screw has the following design. The differential clamping screw clamps a stack of plano-parallel parts and adjusts both the parallelism of the jaws and the clamping force, which is especially important in curved work.

The clamp has two clamping strips connected by two screws. The screw is differential, i.e. with two threads different diameter And different pitch. The screw has a spring-loaded tip, self-adjusting in the recess of the bar. Such a device allows you to first clamp the parts with a screw, and only then with a screw, which, with small dimensions of the clamp, allows you to obtain reliable fastening with a significant clamping force.

To facilitate work and ensure higher accuracy in processing the edges of parts, locksmiths use special devices providing optimal installation of the workpiece, its reliable fixing in the required position and the creation of an accurate direction for the processing tool (file, needle file, abrasive bar, lap). Exist various designs devices: from the simplest filing square to complex frame devices with roller guides, goniometers, sine rulers. To process rectilinear surfaces of templates and patterns, parallels (bastings) are used. Parallel with prismatic guide inserts consists of two hardened and well ground at a right angle slotted strips, in which two guide inserts are placed, tightly seated in the grooves. The movement of the bars relative to each other and the clamping of the workpiece is carried out using two screws.

For locksmith processing of internal right angles for templates, calibers and curved tools, sliding squares are used. At manual processing templates, patterns and various calibers before and after hardening are used universal parallel. This fixture replaces several parallels used to process individual elements of the template profile. It consists of a body, on the side surfaces of which there is a large number of threaded holes M6. The holes are arranged in vertical and horizontal rows at a distance of 10 mm from each other. A bar with a longitudinal groove is attached to one of the end surfaces of the body on pins and screws, which acts as a guide plane along which the working tool moves. On the front side the body has a vertical slot with a through slot along its entire length, in which a slider is placed, moving along the slot. In the desired position, the slider is fixed with a screw located on the back of the housing. In the upper part of the slider there is a through hole, two faces of which form a prism. A screw is screwed from the end of the slider, with which a pin is pressed against the prism, which serves as an axis. A processed template is put on this axis with a technological hole when reproducing the arc sections of its profile. The diameter of the protruding part of the pin is 2 mm. Adjustment to a given radius is carried out by moving the slider along the groove with control of the distance from the pin axis to the working plane of the fixture. The installation is carried out according to the block of end measures and with the help of a curved ruler.

Fitting is the final precise fitting of one part to another without gaps, pitching and distortions. Fit both closed and semi-closed contours. The correctness of the fitting of parts is checked with special template gauges, which are called workings (Fig. 115, c).

When cutting and fitting semicircular parts First, a part is made with inner loop. This detail is called an armhole (Fig. 115, d), since it is easily processed and measured with round rollers and washers. An insert is attached to the processed armhole.

The processing of the armhole is carried out in the following order: first, a wide plane is precisely filed as a base, then rough - ribs 1; 2; 3 and 4, after which they mark the semicircles with a compass, cut them out with a hacksaw (as shown by the dotted line in the figure), accurately file the rib 1 and the semicircular recess and check against the template washer, as well as for symmetry with respect to the axis using a vernier caliper.

Rice. 115. Sawing and fitting parts:

c - check by working out, d - fitting of the liner and armhole, d - fitting of oblique inserts

When processing the liner, wide planes are first filed, and then all four ribs. Next, mark and cut out the corners with a hacksaw, as shown by the dotted line in the figure. After that, precise filing of ribs 5 and 6 is performed in parallel and in the same plane. Then the exact filing and fitting of the liner to the armhole is performed. Fitting accuracy is considered sufficient if the liner enters the armhole without distortions, pitching and gaps.

When sawing and fitting oblique liners and armholes shown in fig. 115, d, processing begins with the insert, since it is easier to process and check. The liner is processed in the following order: first, it is roughly filed, then the wide plane is accurately filed as a base and all four narrow ribs. Next, sharp corners are marked, cut with a hacksaw and accurate filing. And first, ribs 5 and 6 are sawn in a plane parallel to rib 1, then ribs 7 and 8 along a ruler, a square and at an angle of 60 ° to rib 5. They must be symmetrical with respect to the axis of the liner, since the latter must turn over to the armhole. An acute angle of 60° is measured with special angle gauges.

The armhole is processed in the following order: first, a wide plane is precisely filed, after which all four ribs are sawn. Next, marking is carried out, cutting a groove with a hacksaw (shown in dotted line in the figure) and filing ribs 5, 6 and 7. First, the width of the groove is made less than the required one by 0.05-0.1 mm while maintaining the strict symmetry of the lateral edges of the groove with respect to the axis of the armhole; the depth of the groove is immediately accurate in size. Then, when fitting the liner and armhole, the width of the groove receives the exact size according to the shape of the protrusion of the liner. Fitting accuracy is considered sufficient if the insert enters the armhole tightly by hand, without gaps, pitching and distortions.

Increasing labor productivity. When sawing and fitting, you can increase productivity by using special tools and fixtures. These tools and devices include: hand files with interchangeable blades, filing prisms, filing marks, etc.

Hand file with interchangeable blades consists of a body made of light-alloy metal, in which replaceable inserts made of high-quality carbon steel are fixed. The plates are notched. Under each tooth there is a hole through which the removed chips are forced, which protects the teeth from clogging with chips.

This file is used for processing different metals(steel, aluminum, copper), as well as materials (wood, leather, rubber, etc.). After wear, the plates are changed. Experience has shown that prefabricated files are much more productive than conventional ones.

filing prism(Fig. 116, a) consists of two plates 1 with guides 2-3. On the side surface of the plate with a threaded hole 7, a clamping bar 4, a rectangular square 5 and a ruler 6 are fixed. After installing the workpiece, the prism is fixed in a bench vise (Fig. 116, b). Square 5 and ruler 6 are used to check the correct installation of the workpiece.

Rice. 116. filing prisms:

a - general view: 1 - plates, 2, 3 - guides, 4 - clamping bar, 5 - square, 6 - ruler, 7 - threaded hole; b - filing techniques, details in a prism

Sliding frame is a kind of filing prism and has the same purpose. It consists of two metal rectangular bars with grooves along the edges, which include two guide bars connecting these bars.

The rectangular bar is tightly screwed to one end of the guide rails. Such a device allows installation in a sliding frame of workpieces different sizes(within the length of the guide rails).

The frame is installed in a metalwork vise, after which the workpiece is clamped in it, which is then sawn off.

Fitting is the processing of one part on another in order to make a connection. For fitting, it is necessary that one of the parts be completely finished, they are fitting along it. Fitting is widely used in repair work ah, as well as when assembling single products.

Fitting with a file is one of the most difficult jobs for a locksmith, since it has to be processed in hard-to-reach places. It is advisable to perform this operation with bore files, grinding heads, using filing and cleaning machines.

When fitting the liner to the finished hole, the work is reduced to the usual filing. When fitting on a large number of surfaces, first two mating base sides are processed, then the other two are adjusted until the desired pairing is obtained. Details should enter one another without pitching, freely. If the product is not visible through the light, sawing along the paint is carried out.

Sometimes on adjusted surfaces and without paint, you can distinguish traces of friction from one surface to another. Traces that look like shiny spots ("fireflies") show that this place interferes with the movement of one part over another. These places (protrusions) are removed, achieving either the absence of gloss, or a uniform gloss over the entire surface.

In any fitting work, sharp edges and burrs should not be left on the parts, they must be smoothed out with a personal file. How well an edge is smoothed can be determined by running your finger over it.

Fitting is called the exact mutual fit of parts that are connected without gaps during any edge changes. Fitting is distinguished by high processing accuracy, which is necessary for gap-free mating of parts (a light gap of more than 0.002 mm is visible).

Fit both closed and semi-closed contours. Of the two fitting parts, the hole is usually called the armhole, and the part included in the armhole is called the liner.

Armholes are open (Fig. 336) and closed (see Fig. 335). Fitting is carried out with files with fine and very fine notches - No. 2, 3, 4 and 5, as well as abrasive powders and pastes.

In the manufacture and fitting of templates with semicircular outer and inner contours, first a part with an inner contour is made - an armhole (1st operation) (Fig. 336, a). The liner is adjusted (attached) to the processed armhole (Fig. 336.6) (2nd operation).

When processing the armhole, wide planes are first accurately filed as base surfaces, then rough edges (narrow edges) 1,2,3 and 4, after which they mark a semicircle with a compass, cut it out with a hacksaw (as shown by a dash in the figure); produce an accurate filing of a semicircular recess (Fig. 336, c) and check the accuracy of processing with an insert, as well as symmetry with respect to the axis using a caliper.

When processing the liner, wide surfaces are first filed, and then ribs 1, 2 and 3. Next, mark and cut out the corners with a hacksaw. After that, precise filing and fitting of ribs 5 and 6 are performed. Then, precise filing and fitting of the insert to the armhole is performed. Fitting accuracy is considered sufficient if the liner enters the armhole without skew, pitching and gaps (Fig. 336, d).

In the manufacture and fitting of oblique inserts and armholes of the " dovetail"(Fig. 337, h, 6) first I process - * - the liner (processing and checking it is easier). Processing is carried out in the following order (Fig. 337.6). First, wide planes are accurately filed as base surfaces, then all four narrow edges (ribs) 1, 2, 3 and 4. Next, mark the sharp corners (Fig. 337, c), cut them out with a hacksaw and file accurately. rib 7, then ribs 7 and 8 (Fig. 337, a) along the ruler and at an angle of 60 ° to rib 4. An acute angle (60 °) is measured with an angular template.

The armhole is processed in the following order. First, wide planes are accurately filed, after which all four ribs are filed.

Next, marking is done, cutting a groove with a hacksaw (shown in a dash in Fig. 337, c) and filing edges 5, 6 and 7. First, the width of the groove is made less than the required one by 0.05 - 0.1 mm while maintaining the strict symmetry of the side edges of the groove with respect to to the axis of the armhole, the depth of the groove is immediately accurate in size. Then, when fitting the liner and armhole, the width of the groove receives the exact size according to the shape of the protrusion of the liner. Fitting accuracy is considered sufficient if the liner enters the armhole tightly by hand, without gaps, pitching and distortions (Fig. 337, e).

Manual sawing, fitting and fitting are very time-consuming operations. In modern conditions, these operations are performed using metal cutting equipment general and special purpose, in which the role of a locksmith is reduced to managing machines and controlling dimensions.

Curvilinear and shaped parts are processed on grinding machines special profiled abrasive wheels. Wide application they also find electrospark, chemical and other processing methods that exclude additional manual finishing.

However, when performing metalwork and assembly, repair work, as well as during the final processing of parts obtained by stamping, these works have to be done manually.

With the use of special tools and devices, they achieve an increase in the productivity of sawing and fitting. Such tools and devices include hand files with interchangeable blades and wire files coated with diamond grit, filing prisms, filing basting, etc.

In the process of assembling parts into units and products, the jeweler repeatedly, each time before soldering, carries out their fitting - an exact fit to each other (Fig. 5.12).

Shinki fit in to castes, welts, overlays. Their places of attachment are determined design features decorations, but it is always necessary to observe certain patterns developed by practice, i.e. strictly maintain the lower and upper limits of the combination of parts. The lower limit in all cases is the location of the support platform of the shank and the base of the caste or welt on the same level. The upper limit may be different; for deaf castes, it reaches the middle of the caste, for lateral smooth castes, this limit is limited to the conditional line of the bartacking belt, for rimless castes - the height of the openwork, and sometimes the bartacking belts, for prong and corner castes - approximately the middle of the prong or corner, and the welt - the plane its surface.

The process of fitting begins with sawing of areas - alleys on castes or welts and support areas at the shank. The dimensions of the alleys are dictated by the dimensions of the taverns, or rather, the dimensions of their supporting platforms. To ensure high-quality fitting, the notches are made with a step, and support platforms the shank is sawn at the same angle with the notches.

When fitting deaf rim (smooth and openwork) makes casts of the alleys from two opposite sides above the base, and one of the alleys must be on the fugue in order to prevent the seam from diverging during soldering. When fitting prong and most corner castes are made on the welt, exactly against the prongs or corners, and the supporting platforms of the taverns are cut down at an angle of the welt - they are pointed upwards (towards the prong, corner). Shinki are soldered simultaneously to the welt and to the prong or corner, as if connecting the whole bundle together.

When fitting tops vsechki are made on the welt. In those cases when, due to the low height of the welt, it is impossible to make a stitch, the shank is soldered simultaneously to the top and the welt, sawing for this its support pads in the form of a spike and fitting (inserting) them between the top and the welt at an angle that provides high density fit. Such a fitting technique, additionally connecting the top with the welt, increases the reliability of the entire structure.

When fitting overlays it is necessary to proceed from their appearance: invoices are soldered at one end to the top of the shank, and at the other - to the wall of the cast without any notches; the plug-in overlays are supported by one end on the wall of the caste, and by the other (due to the notch) they are cut into the vinca.

rack (checkbox) fit to the caste or welt exactly against the soldered hook; an appropriate slot is made with a needle file, a rack is inserted into it and soldered. The soldering points are cleaned.

Hooks they fit into a cast or welt, making a hole in the cast (by drilling or piercing) and inserting the end of the wire into it, or (in low castes) making a shallow notch (groove) with a needle file and soldering the end of the wire in it. In products with a low welt, the hook is threaded and soldered between the top and the welt. Often (in simple designs earrings) hooks are soldered without pre-training all-rounder and slots.

Fitting is the mutual adjustment of one part to another without gaps, swings and distortions.

The opening of one of the fitted parts is called an armhole, and the other fitting part included in the armhole is called an insert.

Fitting parts by filing is a difficult job, it requires patience and perseverance.

Fitted with special - needle files. Fitted parts should freely fit one into the other. Such requirements apply to many machine parts. The sharp ribs and corners of the parts to be sawn down are the most difficult to fit.

Sharp corner blunting, (smoothing) must not be confused with chamfering. When chamfering on the edge of the part, a flat surface of certain dimensions is made, according to the drawing, while blunting is limited to smoothing sharp edges and deburring.

The fitted surfaces are controlled in the light, as well as with the help of special plates (probes). If the parts to be joined are not visible through the light, they are sawn along the paint.

covering one surface thin layer paints, impose on it another surface of the mating part. Traces (paint stains) show that it is these places that prevent the movement of one part over another.

Spots are removed with a file and this is repeated until the adjusted surface is completely painted. Usually on adjusted surfaces and without paint, traces (in the form of shiny spots) are distinguished from the friction of one surface against another.

Questions

1. What is fitting parts?
2. What is called an armhole?
3. What is an insert?
4. What are the details for?
5. What are the requirements for fitting?
6. How are stocked parts checked?

They are most often fitted in the manufacture of templates and counter-templates. A template is a tool that controls the profile by the "light gap". Patterns are checked against a counterpattern.

The following describes the manufacture of the template (armhole) shown in the figure below.

a - drawing; 6, c and d — processing sequence.

A rectangular billet 82 mm long and 45 mm high (82X45 mm) is cut from sheet steel 3 mm thick. Clean and cover one wide surface solution blue vitriol. A narrow surface is sawn, it serves as a marking base.

Then mark up the template. After drilling (or cutting with a hacksaw), the template armholes are filed with contours in a certain sequence. Side 3 is precisely filed parallel to side 1 and sides 2 and 4, checking them with a ruler and square. The armhole of the template is processed with a semicircular or round file.