Sawing plumbing. General information about plumbing. Self Test Questions
Fitting is the mutual fit of two parts that mate without clearance. Fit both closed and semi-closed circuits. The fit is characterized by high precision machining. Of the two fittings, the hole is called the armhole, and the part entering the armhole is called the insert.
In the manufacture and fitting of templates with a semicircular outer and inner contour, a part with an inner contour is first produced - an armhole (Fig. 151, d). An insert is fitted to the treated armhole.
Processing armholes are in the following order. First, wide planes are precisely filed as base surfaces, then rough - edges 1; 2; 3 and 4, after which they mark a semicircle with a pair of compasses, cut it with a hacksaw (as shown by the dotted line in the figure); make accurate filing of a semicircular recess and check the accuracy of processing according to the template, as well as for symmetry with respect to the axis using a caliper.
When processing the liner, first saw off wide surfaces, and then the ribs 1, 2 and 3. Next, mark the corners and cut them with a hacksaw. After this, the exact filing and fitting of the ribs 5 to 6. is performed. Then, the exact filing and fitting of the insert to the armhole is performed. The accuracy of the fit is considered sufficient if the insert enters the armhole without skewing, pitching and gaps.
In the manufacture and fitting of oblique liners and dovetail armholes depicted in Fig. 151, d, the liner is first processed (processing and verification is easier).
The liner is processed in the following order. First, wide planes are precisely filed as base surfaces, then all four narrow ribs 1, 2, 3 and 4. Next, sharp edges are marked, cut with a hacksaw and precisely filed. First, ribs 5 and 6 are filed in a plane parallel to rib 7, then ribs 7 and 8 in a ruler and at an angle of 60 ° to rib 4. An acute angle (60 °) is measured with an angular gauge.
Next, marking, cutting a groove with a hacksaw (dotted line in the figure) and filing of the ribs 5; 6 and 7. First, the groove width is made less than the required one by 0.05-0.1 mm while maintaining strict symmetry of the side ribs of the groove with respect to the axis of the armhole, while the depth of the groove is immediately accurate in size. Then, when fitting the liner and armhole, the width of the groove gets the exact size in the shape of the protrusion of the liner. The accuracy of fitting is considered sufficient if the insert enters the armhole tight by hand, without gaps, pitching and distortions.
The filing prism (Fig. 152, a) consists of two plates 1 with guides 2 and 3. The lateral surface of the plate has threaded holes 7 for bolting the clamping plate 4, rectangle 5 and ruler 6. Procurement of all four narrow ribs 1, 2, 3 and 4. Next, sharp edges are marked, cut with a hacksaw and precisely filed. First, ribs 5 and 6 are filed in a plane parallel to rib 7, then ribs 7 and 8 in a ruler and at an angle of 60 ° to rib 4. An acute angle (60 °) is measured with an angular gauge.
Fig. 152. Filing prism (a), filing reception (b)
The armhole is processed in the following order. First, broad planes are precisely filed, after which all four ribs are filed.
Next, marking, cutting a groove with a hacksaw (dotted line in the figure) and filing of the ribs 5; 6 and 7. First, the groove width is made less than the required one by 0.05-0.1 mm while maintaining strict symmetry of the side ribs of the groove with respect to the axis of the armhole, while the depth of the groove is immediately accurate in size. Then, when fitting the liner and armhole, the width of the groove gets the exact size in the shape of the protrusion of the liner. The accuracy of fitting is considered sufficient if the insert enters the armhole tight by hand, without gaps, pitching and distortions.
Using special tools and devices, they achieve increased sawing and fitting performance. These tools and fixtures include hand files with interchangeable plates and wire files coated with diamond chips, filing prisms, filing basting, etc.
A hand file with interchangeable plates has a case made of light alloy, in which interchangeable inserts made of high-quality carbon steel are firmly fixed. The plates have notches. Under each tooth there is a hole through which the removed chips are forced, which protects the teeth from clogging.
This file is used for processing steel, aluminum, copper, as well as wood, leather, rubber and other materials. After wear, the plates are changed. Experience has shown that a prefabricated file is significantly more productive than usual.
The filing prism (Fig. 152, a) consists of two plates 1 with guides 2 and 3. The side surface of the plate has threaded holes 7 for bolting the clamping plate 4, rectangle 5 and ruler 6. The blank is installed between the guides 2 and 3 so that the metal layer to be removed protruded above the planes of the guides, and is firmly fixed with a clamping bar 4. The prism is fixed in a bench vise (Fig. 152, b). Squares 5 and a ruler 6 are used to verify the installation of the workpiece.
The sliding frame is a kind of filing prism and has the same purpose. It consists of two rectangular metal bars having grooves at the edges, which include two guide bars connecting these bars.
The rectangular block is tightly screwed to one end of the guide rails. Such a device allows the installation in a sliding frame of workpieces of different sizes (within the length of the guide rails).
The frame is installed in a bench vise, after which the workpiece is clamped in it, which is then filed.
Self Test Questions
- What are the features, techniques and rules of fitting?
- How is sawing and fitting of trihedral holes?
- What tools are used for sawing and fitting?
Purpose, types, essence, techniques and sequence of execution
The fitting operations of locksmithing include: fitting, fitting, lapping and lapping.
For fit One part to another, first of all, it is necessary that one of the parts be completely finished - fitting is carried out along it. In fitting sliding parts, the most significant obstacle is sharp ribs and corners of the sawn surfaces. They are adjusted until the mating parts begin to enter one into another freely, without a gap. If the connection to the lumen is not visible, they are sawed over the paint. On customized surfaces, traces of the friction of one surface on another can also be distinguished without paint. These traces, in the form of shiny spots, show that it is these places that interfere with the movement of one part over another. Brilliant places (or traces of paint) are filed with a file until the part is finally ready. For any fitting work, sharp ribs and burrs must not be left on the parts; they need to be smoothed out with a file, as you can get hurt about them. The quality of processing the ends and ribs can be judged by swiping them with a finger.
The notion of “smoothing an edge” cannot be confused with the notion of “chamfering”. When chamfering on the edge of the part, they make a small flat ribbon, inclined at an angle of 45 ° to the side faces of the part.
Fitting Mutual fitting of parts mating without clearance is called. Fit both closed and semi-closed circuits. Fittings are characterized by high precision machining. In stocked parts, the hole is called the armhole, and the part included in the armhole is called the liner. Templates, counter templates, stamping tools (punches and dies) are subjected to fitting, etc. The working parts of the template and counter template must be fitted so that when the sides of the template and the counter template come in contact, there is no gap between these sides for any of the possible mutual re-editions of the template and counter-pattern.
Lapping - surface treatment of the product by lapping, which is a tool made of soft materials with grinding powder. Using lapping, the thinnest metal layer (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 performed after work with a file or a scraper for the final surface finish of the workpiece and giving it the greatest accuracy. Lapping is a very accurate finishing operation and is used to provide tight, tight detachable and movable joints (connection of parts of taps, valves, well-retaining liquid and gases). The lapping accuracy of the parts is from 0.001 to 0.002 mm, or until the mating surfaces completely coincide. The allowance for this operation is 0.01-0.02 mm. Lapping is performed on the stove. 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 most commonly used are engine oil, kerosene, gasoline, toluene, alcohol.
In order to grind the part, abrasive powder mixed with oil is applied with a thin even layer on the lapping plate. The part is placed with a rubbed surface on the plate and in a circular motion it is moved throughout the plate until a matte or glossy (shiny) surface is obtained.
In the process of grinding, the mechanical removal of metal particles is combined with chemical reactions. When working with abrasive substances, the treated surface is oxidized under the influence of abrasive and oxygen. By lapping, this film of oxidized metal is removed from the surface, but the surface is immediately oxidized again. Thus, the metal is removed until the surface acquires the required accuracy and purity of processing.
Fine-tuning perform on pre-sanded surfaces, with an allowance for finishing from 0.01 to 0.02 mm. Finishing is a type of lapping and serves to obtain not only the required shapes and surface roughness, but also the specified dimensions of the parts with high accuracy. Finishing surfaces are more durable, which is a determining factor for measuring and calibration tools and very precise parts.
Work tools and accessories
An important condition for high-quality machining of adjustable surfaces and holes is the right choice of files. Files are selected according to the cross-sectional profile depending on the shape of the surfaces and holes being machined: for grooves and holes having a square section, square files, for rectangular files, flat and square files, for trihedral files, trihedral, rhomboid 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 treated (in length) plus 200 mm. When processing curved surfaces of holes in the form of radial, oval or complex curved contours, round or semicircular files are used, in which the radius of curvature should be less than the radius of curvature of the processed contour. The packing is done with files with small and very small notches - No. 2, 3, 4 and 5, as well as abrasive powders and pastes.
The correct selection of fasteners, such as a manual vice, which quickly fix the workpiece, also contributes to high-quality machining of parts. Their design allows you to clamp the part in a vice with a conical device that spreads and brings down the jaws when rotating a round handle with a knurled surface. Slanting jaws to a vice are used to clamp parts when filing inclined surfaces and chamfering. Slanting jaws are inserted between the jaws of a conventional parallel bench vice.
The patterned vice is used to perform operations that require high accuracy of basing and reliability of fixing the part (when marking, drilling, reaming, flat and profile grinding). This vice differs from machine vice in high precision of manufacturing and the possibility of their installation on three mutually perpendicular planes. The fixed sponge is integral with the body. The design of the movable jaw allows it to move along the finely polished plane of the body. In this case, the direction of the jaws is set 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 with the screws tightened allows the parts to move along a sliding fit relative to the guides of the housing. The jaw is moved by means of a screw rotating in a nut fixedly mounted on the body and locked with a pin locked in the movable jaw. The lateral surfaces of the patterned vice are strictly perpendicular to the polished base and parallel to each other, and the clamping planes of the jaws are perpendicular to the base and the upper plane of the vice. All the main details of the vice are made of U7A steel, subjected to heat treatment to hardness НРС 55-58 and grinding with tolerances in 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 the package of plane-parallel parts and adjusts both the parallelism of the jaws and the clamping force, which is especially important when machining.
The clamp has two clamping bars connected by two screws. Differential screw, i.e. with two threads of different diameters and different pitch. The screw has a spring-loaded tip, self-aligning 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 the small dimensions of the clamp, makes it possible to obtain reliable fastening with significant clamping force.
To facilitate the work and ensure higher accuracy of processing the edges of the parts, the fitters use special tools that ensure optimal installation of the workpiece, secure it in the required position and create an exact direction for the processing tool (file, file, abrasive bar, lapping). There are various designs of devices: from the simplest filing square to complex frame devices with roller guides, goniometers, sine bars. To process the rectilinear surfaces of patterns and patterns, parallels (markings) are used. The parallel with the prismatic guiding inserts consists of two strips with hardened and well sanded at right angles, in which two guiding inserts are placed, which are tightly seated in the grooves. Moving the strips relative to each other and clamping the workpiece is done using two screws.
For the plumbing of internal right angles of the templates, calibers and pattern tools, sliding angles are used. For manual processing of templates, patterns and various calibers before and after quenching universal parallel. This tool replaces several parallels used to process individual elements of the template profile. It consists of a housing, on the side surfaces of which there are a large number of holes with M6 thread. The holes are arranged in vertical and horizontal rows at a distance of 10 mm from each other. A strap with a longitudinal groove is attached to one of the end surfaces of the housing on the pins and screws, which acts as a guide plane along which the working tool moves. On the front side of the case there is a vertical groove with a through slot along its entire length, in which a slider is placed that moves along the groove. In the desired position, the slider is fixed with a screw located on the back of the case. In the upper part of the slider there is a through hole, the two faces of which form a prism. A screw is screwed from the end of the slider, with the help of which a pin serving as an axis is pressed against the prism. A machined 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 device. Installation is carried out on the block of end measures and using a straightedge.
steel or carbide.
Disk scraper used for scraping wide planes. A disk with a diameter of 50 ... 60 mm and a thickness of 3 ... 4 mm is sharpened on a circular grinding machine. In this way, the entire scraper disk is used, which increases labor productivity.
Sharpening. Often, the sharpening angle of the cutting part of the steel scraper is assumed to be 75 ... 90 degrees. Scraper sharpening angles for processing cast iron and bronze 75 ... 100 degrees, for rough scraping of soft metals 35 ... 40 degrees.
After sharpening, barbs and irregularities form on the blade of the scraper, so the blade is finished by being carried out on abrasive bars with a grain size of 90 or lower. For precise scraping and final finishing of the cutting part of the scraper, GOI pastes are accepted. On average, over 7 hours of work, the scraper is adjusted 4 ... 6 times depending on the nature of the scraping and the material being processed.
Before scraping, surface irregularities are revealed by staining them with a mixture of machine oil and azure. Azure can be replaced with soot mixed in a mixture of autol with kerosene.
Paint is applied to the surface of the plate with a swab of clean linen rags folded in several layers. It is convenient to stain with a bag made of a clean canvas (canvas), in which the paint is applied.
In small depressions, the paint will accumulate, but in places deeper it will not. So white spots appear in the most in-depth places that are not covered with paint; dark spots less deep places in which paint has accumulated; gray spots are the most prominent places on which the paint lies in a thin layer.
Safety. When scraping, the following safety requirements must be met:
the workpiece must be securely installed and firmly fixed;
work with faulty scrapers (without handles or with cracked handles) is not allowed;
when working with grinding heads, observe the electrical safety rules.
Sawing and stocking
51. Sawing
Sawing is the processing of holes in order to give them the desired shape. The processing of round holes is carried out with round and semicircular files, trihedral trihedral, hacksaw and rhombic files, square square files.
Sawing in the workpiece of the handle of a square hole. First, mark the square, and in it a hole, then drill a hole with a drill, the diameter of which is 0.5 mm less than the side of the square.
Further processing of the sides is carried out until the square head easily but firmly fits into the hole.
Sawing a three-sided hole in a workpiece. Mark the outline of the triangle, and in it a hole and drill it with a drill, without touching the markings of the triangle. The gap between the sides of the triangle and the inserts when checking with a probe should be no more than 0.05 mm.
52. Fit and fit
Fit called processing one part over another in order to complete the connection. This operation is widely used in repair work, as well as in the assembly of individual products.
For any fitting work, sharp edges and burrs cannot be left on the parts; they must be smoothed out with a personal file. How well the edge is smoothed can be determined by drawing a finger over it.
Fitting called the exact mutual fit of parts that connect without gaps for any turning. The fit is done with files with small and very small notches - No. 2, 3, 4 and 5, as well as abrasive powders and pastes.
In the manufacture and fitting of templates with a semicircular outer and inner contours, the part with the inner contour of the armhole is first manufactured. To the processed armhole fit (fit) the liner.
Manual sawing, fitting and fitting are very time-consuming operations. However, when performing fitter's and assembly, repair work, as well as during the final processing of parts obtained by stamping, it is necessary to perform these works manually. The use of special tools and devices (hand files with interchangeable plates, wire files coated with diamond chips, filing prisms, etc.) increases labor productivity when sawing and fitting.
GRINDING AND FINISHING
53. General information. Lapping materials.
General information. Lapping called processing of parts working in pairs to ensure the best contact of their working surfaces.
When sawing openings, open circuits and holes, the following rules must be observed:
1. It is rational to determine the method of preliminary formation of sawn openings and holes: in parts with a thickness of up to 5 mm - by cutting, and in parts with a thickness of more than 5 mm - by drilling or reaming, followed by cutting or cutting the jumpers.
2. When drilling, drilling, cutting or cutting out jumpers, it is necessary to strictly monitor the integrity of the marking marks, leaving an allowance for processing of about 1 mm.
3. A rational sequence of processing openings and holes should be observed: first, process straight sections of surfaces, and then curved sections associated with them.
4. The process of sawing openings and holes must be periodically combined with checking their contours according to a control template, insert or workout.
5. The corners of the openings or holes must be finished clean with a file edge of the corresponding cross-sectional profile (No. 3 or 4) or files, checking the quality of processing with workings.
6. Finishing the surface of the holes should be done with a longitudinal stroke.
7. For the final calibration and finish of the hole, use notches, broaches and firmware on a screw or pneumatic press (Fig. 4.2).
8. The work should be considered completed when the control template or insert completely, without pitching, enters the opening or hole, and the clearance (gap) between the template (insert, output) and the sides of the contour of the opening (hole) is uniform.
Fit rules
When fitting The following rules must be observed:
1. The fitting of two parts (pairs) to each other should be carried out in the following order: first, one part of the pair is made and finished (usually with external contours) - an insert, and then another, paired according to the template, is fitted and fitted (fitted) to it detail - armhole.
2. The quality of the fit should be checked by the clearance: in the gap between the parts of the pair, the clearance should be uniform.
3. If the contour of a pair of parts - the liner and the armhole - is symmetrical, they should be mated effortlessly with a uniform gap when turning 180 °.
Typical defects during sawing and fitting parts, the reasons for their appearance and methods of prevention are given in table. 4.1.
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Table 4.1 Typical defects during sawing and fitting parts, the reasons for their appearance and methods of prevention
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The end of the table. 4.1
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Fitting is the mutual fitting of one part to another without gaps, swings and distortions.
The hole of one of the fittings is called the armhole, and the other fitment part included in the armhole is called an insert.
Fitting parts by filing is a difficult job, it requires patience and perseverance.
Fit with special, - files. The fitted parts must fit one into the other freely. Such requirements impose on many parts of machines. The sharp ribs and corners of the sawed surfaces of the parts are most hindering the fitting.
Blunting sharp edges, (smoothing) cannot be mixed with chamfering. When chamfering on a rib, parts make a flat surface of certain sizes, according to the drawing, while blunting is limited to smoothing sharp ribs and deburring.
Control the prepared surfaces for clearance, as well as using special plates (probes). If the connected parts are not visible in the lumen, they are sawed over with paint.
Having covered one surface with a thin layer of paint, impose on it another surface of the mating part. Traces (spots from paint) show that it is these places that interfere with the movement of one part over another.
The spots are removed with a file and so repeated until the adjustable surface is completely painted. Usually on adjustable surfaces and without paint they distinguish traces (in the form of shiny spots) from the friction of one surface against another.
Questions
- What is fitting parts?
- What is called armhole?
- What is an insert?
- Why fit parts?
- What are the requirements for fitting?
- How to check fittings?
Fit most often in the manufacture of templates and counter-patterns. A template is a tool that controls the profile by the "light gap". Check pattern check templates.
The following describes the manufacture of the template (armhole), shown in the figure below.
a - drawing; 6, c and d are the processing sequence.
A rectangular blank 82 mm long and 45 mm high (82X45 mm) is cut from sheet steel 3 mm thick. They clean and cover one wide surface with a solution of copper sulfate. They saw a narrow surface, it serves as a basis for marking.
Then mark up the template. After drilling (or cutting with a hacksaw), the armholes of the template file the contours in a certain sequence. Precisely filed side 3 parallel to side 1 and sides 2 and 4, checking them with a ruler and a square. The pattern is treated with a semicircular or round file.
