To category:
metal cutting
The essence of sawing and fitting
In the practice of locksmith processing, the processes of sawing and fitting are quite common, especially when performing repair and assembly work, as well as in the tool shops of machine-building plants.
The essence of the sawing process is that by processing round holes with files of various profiles, square, rectangular, oval and other shapes are obtained.
In a number of cases, blanks for machine parts and products with holes of the desired shape are also obtained by stamping, however, their final processing is also carried out with files by sawing to the dimensions indicated on the drawings. In order not to damage the walls of the hole being sawn by the side faces of the file, its cross section must be less than the size of the hole. Sawing holes in parts with narrow, flat and straight surfaces is carried out using bastings, frames and parallels.
Fitting - the final precise fit of one part to another without any gaps, swings and distortions. In this case, one of the parts before fitting and fitting must be processed within the specified accuracy.
Templates, counter-templates, matrices and punches of stamps, etc. are subjected to fitting. The working parts of the template and counter-template must be fitted very accurately, so that when connecting the fitted sides of the template and counter-template, there is no gap between them for any of the possible mutual permutations.
They fit both closed (closed) and semi-closed (open) contours. These contour cavities (holes) are called armholes.
The correctness of their contours is checked by special template gauges called workings.
Sawing and filing are very labor intensive manual processes; where possible, they try to mechanize.
steel or hard alloy.
Disc 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. Thus, the entire scraper disk is used, which increases labor productivity.
Sharpening. Often the angle of sharpening of the cutting part of the scraper for steel is taken equal to 75 ... 90 degrees. The sharpening angles of the scraper for processing cast iron and bronze are 75 ... 100 degrees, for rough scraping of soft metals 35 ... 40 degrees.
After sharpening, burrs and irregularities form on the blade of the scraper, so the blade is adjusted by carrying out on abrasive bars with a grain size of 90 and below. For precise scraping and final finishing of the cutting part of the scraper, GOI pastes are used. On average, for 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 with a mixture of autol and kerosene.
The paint is applied to the surface of the plate with a swab of clean linen rags folded in several layers. It is convenient to carry out staining with a bag made of clean linen (canvas) into which paint is applied.
In small recesses, the paint will accumulate, and in more recessed places it will not. This is how white spots appear - the most in-depth places that are not covered with paint; dark spots are 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;
it is not allowed to work with defective scrapers (without handles or with cracked handles);
when performing work with grinding heads, observe the rules of electrical safety.
SAWING AND PACKING
51. Sawing
Sawing is the processing of holes in order to give them the desired shape. Processing of round holes is carried out with round and semicircular files, triangular triangular, hacksaw and rhombic files, square square files.
Sawing a square hole in a workpiece. First, a square is marked, and a hole in it, then a hole is drilled 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 fits easily but tightly into the hole.
Sawing a trihedral hole in a workpiece. Mark the contour of the triangle, and in it a hole and drill it with a drill, without touching the marking marks of the triangle. The gap between the sides of the triangle and the liners when checking with a probe should be no more than 0.05 mm.
52. Fit and fit
Fit called the processing of one part on another in order to make a connection. This operation is widely used in repair work ah, as well as when assembling single products.
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 called the exact mutual fitting of parts that are connected without gaps in any perekantovki. 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, a part with an inner contour of an armhole is first made. The liner is adjusted (attached) to the processed armhole.
Manual sawing, fitting and fitting are very time-consuming operations. 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 performed manually. Application special tools and accessories (hand files with interchangeable blades, wire files coated with diamond grit, filing prisms, etc.) increases productivity when sawing and fitting.
GRINDING AND FINISHING
53. General information. Lapping materials.
General information. Lapping called the processing of parts working in pairs to ensure the best contact of their working surfaces.
Study questions:
-1. The essence of sawing and fitting.
-2. Basic rules for sawing and fitting parts.
-3. Typical defects in sawing and fitting parts, their causes and ways to prevent them.
Download:
Preview:
To use the preview of presentations, create a Google account (account) and sign in: https://accounts.google.com
Slides captions:
Discipline "Technology of plumbing work" College ISTiD (branch) NCFU in Pyatigorsk Goncharov Oleg Yuryevich College teacher
Topic 11. Sawing and fitting 1. The essence of sawing and fitting. 2. Basic rules for sawing and fitting parts. 3. Typical defects in sawing and fitting parts, their causes and ways to prevent them. Study questions:
1. The essence of sawing and fitting Sawing is a kind of filing. When sawing, a hole or opening is processed with a file to ensure the specified shape and size after this hole or opening is previously obtained by drilling, drilling the contour, followed by cutting out jumpers, sawing an open contour (opening) with a hand saw, stamping, etc. The peculiarity of the sawing operation is processing quality control (size and configuration) is carried out with special testing tools - templates, workings, inserts, etc. (Fig. 1.1) along with the use of universal measuring tools.
Continuation of question 1 Fig. 1.1. Template and insert: a - template; b - production; c - liner Fitting is a locksmith operation for mutual fitting by means of filing two mating parts (pairs). Fitted contours of pairs of parts are divided into closed (such as holes) and open (such as openings). One of the attached parts (with a hole, an opening) is called an armhole, and the part included in the armhole is called an insert.
2. Basic rules for sawing and fitting parts Rules for sawing 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 out, and in parts with a thickness of more than 5 mm - by drilling or reaming, followed by cutting out or cutting jumpers. 2. When drilling, reaming, punching or cutting out jumpers, it is necessary to strictly monitor the integrity of the marking marks, leaving a processing allowance of about 1 mm. 3. You should follow a rational sequence for processing openings and holes: first, process straight sections of surfaces, and then - curved sections associated with them.
Question 2 continued 4. The process of sawing openings and holes must be periodically combined with checking their contours according to a control template, insert or working. 5. The corners of openings or holes must be finished with a file edge of the corresponding cross-sectional profile (No. 3 or 4) or needle files, checking the quality of processing by workings. 6. Finishing the surfaces of the holes should be done with a longitudinal stroke. 7. For the final calibration and finishing of the hole, punching, broaching and flashing on a screw or pneumatic press should be used (Fig. 2.1). Rice. 2.1. Cylindrical firmware
Question 2 continued 8. The work should be considered completed when the control template or liner completely, without pitching, enters the opening or hole, and the clearance (gap) between the template (liner, working) and the sides of the opening (hole) contour is uniform. Fitting rules: 1. The fitting of two parts (pairs) to each other should be carried out in the following order: first, one part of the pair (usually with external contours) is made and finished - an insert, and then, according to it, as in a template, it is marked and fitted (fitted ) another mating part is an armhole. 2. The quality of the fit should be checked by clearance: in the gap between the parts of the pair, the clearance should be uniform. 3. If the contour of a pair of parts - an insert and an armhole - is symmetrical, they should, when edging 180 °, be mated effortlessly, with a uniform gap.
3. Typical defects when sawing and fitting parts, their causes and ways to prevent Defect Cause Prevention Misalignment of the opening or hole in relation to the base surface of the part Misalignment when drilling or reaming. Insufficient control when sawing Carefully monitor the perpendicularity of the tool to the base surface of the workpiece when drilling and reaming the opening (hole). In the process of work, systematically check the perpendicularity of the plane of the opening (hole) being sawn to the base surface of the part. Non-observance of the shape of the opening (hole) Sawing was performed without checking the shape of the opening (hole) according to the template (shu inserts). "Gouges" for the marking when cutting out the contour First, sawing should be carried out according to the marking (0.5 mm to the marking line). The final processing of the opening (hole) should be carried out with a thorough check of its shape and dimensions. measuring instruments or template (insert)
Question 3 continued Non-coincidence of the symmetrical contours of the fitted pair (insert and armhole) when they are turned over by 180° One of the parts of the pair (counter-template) is not made symmetrically Carefully check the symmetry of the insert during marking and manufacturing One of the parts of the pair (armhole) is loose adjoins another (insert) in the corners Obstructions in the corners of the armhole Follow the rules for processing parts. Cut through the corners of the armhole with a hacksaw or saw with a round file.
Sawing holes
To category:
Scraping, lapping, etc.
Sawing holes
Sawing is the processing of holes in order to give them a certain (given) shape. Round, oval, trihedral, square, rectangular and other shapes are found in products and their details. All such holes can be processed by sawing manually and mechanically.
Round and oval holes are sawn with round, semicircular and oval files, triangular holes - with trihedral, hacksaw and diamond-shaped files, square holes - with square files, rectangular holes - with square and flat files.
In order for the side edges of the file not to damage the side walls of the hole being sawn, its cross section must be less than the size of the hole.
For sawing holes in parts with narrow, flat and straight surfaces, bastings, frames and parallels are used.
Consider a few examples of sawing holes.
Manufacture of strip steel plate with a hole in the middle.
This work should be done like this:
1) measure and mark the length of the plate on the strip and cut off the blank from the strip;
2) straighten the plate on the plate;
3) file sides 2 and 4 along the square applied to sides 1 and 5;
4) remove burrs from the edges of the plate;
5) mark and mark the center of the hole, mark and mark the contour of the hole for punching;
6) departing 2 mm from the line of the applied contour, draw the contour of the hole for sawing;
7) straighten the plate;
8) cut the cut hole at risk;
9) remove the burrs from the edges of the hole..
Rice. 1. Steel plate (detail)
Sawing a trihedral hole template in the workpiece according to the marking (Fig. 2). Machining accuracy 0.05 mm on the probe.
The work must be done in the following sequence:
1) mark the contour of the hole to be sawn and drill it;
2) file three corners of the trihedron in the round hole of the workpiece;
3) sequentially cut the sides of the hole, not reaching 0.5 mm to the risks;
4) cut sides / and 2 to the risks and fit them to the square and using the control insert;
5) cut side 3 to the mark and fit it to sides 1 and 2 on a square with a check with an insert;
6) adjust sides 1, 2 and 3 of the trihedron so that the insert enters the hole freely; the gap between the side of the template and the insert when checking with a probe should be no more than 0.05 mm; after fitting, remove the burrs from the sharp edges of the triangular hole. Sawing a square hole in the workpiece by marking.
Rice. 2. Template with triangular hole
Rice. 3. Crank with a square hole
The hole is processed as follows:
1) drill a hole in the workpiece -
2) apply risks along the boundaries of a given square hole;
3) file four corners in the hole with a square file, not reaching 0.5 mm to the marks;
4) they cut (align) in the hole of the side of the square, not reaching 0.5 mm to the risk;
5) sawing all sides of the square to the risks;
6) adjust the sides of the hole along the square head of the tap or reamer, while first sawing the sides (the tap head should still enter the hole only with the ends and only to a depth of 1-2 mm), then sawing the sides 2 and 4 and then finally processing one by one the other all sides, finishing the fit when the square head will easily and without rolling into the square hole;
7) deburr the sharp edges of the square hole.
Rice. 4. Sawing a window in a cast iron bar
Sawing a window in a cast-iron bar.
This work needs to be done like this:
1) mark the window according to the dimensions of the drawing and remove the jumpers between the round holes of the workpiece with a crosscut;
2) cut off the formed protrusions to the risks;
3) cut the hole to size according to the caliper with a flat personal file with semicircular ribs;
4) remove the burrs from the edges of the sawn window.
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. The places of their fitting are determined by the design features of the decoration, 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 sizes of the alleys are dictated by the sizes of the taverns, and more precisely in size their strongholds. To ensure high-quality fitting, the notches are made with a step, and the support pads of the taverns are sawn at the same angle with the notches.
When fitting deaf rim (smooth and openwork) he casts the vaults from two opposite sides above the base, and one of the vase 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 the same cases, when it is impossible to make a welt due to the low height of the welt, the shank is soldered simultaneously to the top and the welt, sawing down its support pads in the form of a spike for this and fitting (inserting) them between the top and the welt at an angle that ensures a high 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 are inserted 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 of earrings) hooks are soldered without preliminary preparation of notches and slots.