Agreed: at the meeting of the methodical commission.

"__" ___________ 2015

Lesson plan number 1.3

  The topic of study program: PM 01. Metal Correction. Bending metal.

  Theme of the lesson. Editing and bending plates and rods.

The purpose of the lesson.   Teach the student to properly edit and bend plates and rods.

  Material technical equipment of the lesson.   Posters, samples, process cards, sheet and bar steel (billets), hammers, measuring and marking tools, vice, plate, chalk, fixtures.

Course: 6 hours.

1. Introductory group briefing 50 min

a) examination of knowledge on the material 10 min

How to organize a workplace lie the cutting of metal in a vice?

1. What rules must be observed when securing a blanks of metal band cutting for the level of vise jaws?
2. How to position the chisel in relation to the vise and the workpiece when chopping a strip metal to the level of the vise jaws?

1. Why is it necessary to look at the cutting edge of the chisel, and not at its head, when cutting a strip metal according to the level of the jaw sponges?
2. Why do you cut chamfers on the front and rear edge of the part before cutting down a metal layer on a wide flat surface?

6, in what sequence to produce chopping on the wide flat surface of the part of the metal layer;

a) 1 mm thick?

b) 3 mm thick?

Why is it recommended to end the cabin from the reverse side when chopping parts from brittle materials (cast iron, bronze, etc.)?

8. What is the difference in cutting techniques of curvilinear grooves with a filler:

a) on a wide flat part surface?

b) on the curved surface of the part (lubricant grooves in the bearing shell)?

9. How to organize a workplace when cutting metal on a plate? 10. How to chop on the stove:

a) strip with a section of 20x5 mm?

b) round bar with a diameter of 10 mm?

c) square bar section 10x10 mm?

g) sheet metal 2 mm thick?

11. What cutting tools to apply for cutting in the sheet metal hole:

a) with a diameter of 20 mm "?

b) with a diameter of 70 mm?

12. How to make sharpening cutting tools for cutting (chisel, cutter, trench)?

1. Why is a chisel for cutting sheet metal is recommended to sharpen with a small curvature of the cutting edge?
2. It is known that the smaller the sharpening angle of the tool, the sharper it is. Why, in this case, is the chisel for cutting more solid metal sharpened at a greater angle than for cutting a soft metal?
3. What safety rules must be followed when:

a) hand cutting in a vice?

b) manual chopping on the stove?

c) mechanized wheelhouse?

d) sharpening tools for cutting?

16. Why do the hammer face and the end of the chisel hammer make rounded?

b) students explaining new material 30 min

Editing and straightening -   represents the operations of the alignment of metal, workpieces and parts that have dents, bulge, waviness, warping, bending, etc.

Editing and straightening   It has the same purpose, but differs in the techniques of implementation and the tools and devices used. The metal is being edited both in cold and heated condition.

Choice of -   depends on the size of the deflection, size and material of the product.

Edit   can be carried out manually on a steel or cast iron plate or on the anvil and by machine on presses.

When editing   apply the correct plate, hammers of different mass and material, with plug-in strikers, trowels - wooden or metal bars are used when editing thin sheet and strip metal. Apply also other devices.

Editing sheet metal more complex than the bar and rods. Noting the bulge of its border bends with chalk or graphite. After that, the blank is placed on the slab so that the edges of the blank are not hanging down and pressing it with the hand begins editing. To stretch the billet middle, hammering is applied from the middle of the billet to the edge. Stronger strikes are applied in the middle and reduce the impact force closer to the edge. In order to avoid cracks and the work hardening of the material it is impossible to apply repeated blows at the same place of the workpiece.

When editing rods and flat metal   after the mark is placed on the slab bulge up. The blows with a hammer are applied on the convex part from the edges of the bend to the middle part, adjusting the force of the blow depending on the bar diameter and the bend size and as the bend is straightened. Finishing editing with light strokes and turning the rod around the axis.

Bending -   method of metal processing by pressure, in which the billet or its part is given a curved shape. Bending is performed with different hammers in a vice, on a plate or with the help of special tools. Thin sheet metal and wiring up to 3 mm bend with mallows, pliers or round pliers. Bending produce both by handon the supporting tool and mandrels, and on bending machines (presses). The essence of bending lies in the fact that one part of the workpiece is bent relative to the other at a given angle. Perform both in cold and in hot condition.

Square bending   from flat steel perform the following order; Determine the length of the workpiece sweep, add the length of the sides of the bracket with an allowance of 0.5 mm for one bend. Mark the length with an additional allowance for processing the ends of 1 mm on the side and cut down the chisel with a chisel. Straighten cut out the workpiece on the plate. Saw in the size of the drawing. They cause bending risks. Clamp the workpiece in a vice at the level of risks and hammer blows end of the bracket (the first bend). Rearrange the workpiece in a vice, clamped between the jaws and the bar mandrel longer than the end of the bracket bend the second end (second bend). Remove the workpiece and remove the bar - mandrel, clamp the brackets in a vice at the level of the jaws with inserted mandrel or square in size.

Bend the first and second legs, make the fourth and looped bend.

Check and straighten on the square. Burrs are removed on staples.

It is flexible pipes it is made with fillers and without fillers.

The method of bending depends on the diameter of the pipe, the magnitude of the angle of the bend and the material of the pipes used by hand or mechanized method, cold or hot bending. Apply pipe bending equipment.

Safe working rules for metal bending

1. Securely secure the workpiece in a metal vice or fixtures.
2. Work only on serviceable equipment and devices.
3. Bench hammers should have good handles, be tightly seated and propped.
4. During the work on bending machines and cars precisely to observe the safety rules stated in special leaflets.

5. When bending pipes in the hot state to work in mittens.

c) securing the material by introductory briefing 10 minutes.

1. How to organize a workplace for bending metal?
2. How to bend a metal strip 4 mm thick in a vice:

a) at right angles?

b) at a given obtuse angle?

c) at a given acute angle?

d) in the bracket

3. How to bend a round bar with a diameter in a ring with an inner diameter of 30 mm:

1. How to bend a bracket from a metal strip 2 mm thick using a bending device?
2. Why in the bending hand presses at the ends of the levers, which rotate the screw, install massive balls?
3. How to bend in a cold state a metal strip with a section of 20x5 mm "on the edge" at an angle of 90 0?
4. Suggest a method of bending “on the edge” of a metal strip with a section of 10x3 mm without a device.
5. Why do you fill pipes with sand or other fillers?
6. Why is it possible to bend pipes without filler in a bending roller device?

10. What safety rules should be applied when bending a megalith strip and pipes?

g) task for the day

1. To edit the plates and bars.
2. Bend plates and rods.

2. Independent work of students and current instruction (targeted workarounds) 4 h. 40 min.

1. Check the organization of student workplaces.
2. Compliance with the rules of TB.
3. Check the quality of work performed.
4. Indicate student errors and their correction.

  Typical difficulties and mistakes of students and their warning

During the bending of the metal, students have difficulty in determining the allowance for bending, as well as in observing the accuracy of the installation of blanks in a metal vice and striking. It depends on the requirements when bending. It is necessary to more accurately determine the allowances on the table and properly strike.

Students have particular difficulties with bending pipes in a heated state: they incorrectly heat the pipe, do not fill it with sand sufficiently, apply undisturbed or wet sand. In order to avoid possible mistakes, students need to fulfill all necessary requirements and rules for performing bending works.

As a result of the exercises 1 —5 of the training and production card the student must:

know the purpose and how to perform the operation are flexible; used machines, tools and simple devices; rules for bending work; requirements for the organization of the workplace; methods of work with the use of mechanized means; the rules of safe work to be able to bend in a cold state, the strip, sheet and rod metal at different angles; bend pipes in a cold and hot state; use mechanized means of bending; follow the rules of safe work and workplace organization.

3.   Cleaning jobs. 10 min.

1. Students clean up jobs, rent out tools and their work.

4. Final briefing. Analysis of the working day. 15 minutes.

1. Mark the work of the best students.
2. Mark student failures.
3. Answer student questions.
4. Post grades in a journal.

5. Homework. 5 minutes.

Acquaintance with the material of the next lesson, repeat the topic "Editing and bending of metal." Textbook "Plumbing" author Skakun V.A.

Master of Industrial Training _________________________________________________

A locksmith often has to bend bands, rods, make squares, loops, brackets, etc. at a certain angle and radius of the bend.

As a rule, the length of the workpiece is indicated on the drawing. In cases where the length of the workpiece is not specified, the profile should be divided into sections, determine the length of each of them and summarize. For example, you need to determine the length of the blank strip metal for a square.

The length of the square consists of three sections - two straight and curvilinear. The length of the straight sections is determined by the drawing, and the length of the curvilinear is found by the formula

where g is the bend radius, mm; α - bend angle, hail; π = 3.14.

The length of the workpiece for a ring with an outer diameter of 100 mm is determined by the formula

I - πd. = 3.14 x 100 = 314 mm.

Double corner bending (Fig. 104). The operation is performed after marking the sheet, cutting the workpiece, editing it on the plate and filing the width of the size of the drawing. Prepared in this way, the workpiece 1 is clamped in a vice 2 between the nubkins 3 and the first shelf of the elbow is bent, and then one barrel is replaced with a bar-lining 4 and the second shelf is bent. At the end of the bend, the ends of the square are filed with a file in size and remove burrs.

Fig. 104. Bending double angle in a vice:
  1 - preparation. 2 - a vice, 3 - nagubnik, 4 - a lining

Bending parts at angles not equal to 90 °. Such parts are subjected to bending on special mandrels, the size and shape of which correspond to the size and shape of the part.

Bending staples. In this case, use a cylindrical mandrel. The diameter of the mandrel should correspond to the size of the bracket groove. Bending during bending should be applied on the upper plane of the bracket.

Bending sleeve. The sequence of transitions during bending of a cylindrical sleeve on the mandrel is as follows: first one side of the part bends on the sleeve, and then the blows are applied to the second, and then both ends are connected.

Bending in devices significantly reduces the time and cost of manual labor and improves the quality of processing.

Bending at an angle of 90 ° details of the type of bracket from a thin wire produced by round pliers, and from a wire with a diameter of more than 3 mm - in a vice on the mandrel. The billet is placed in a vertical position and bent with a hammer. The shape and size of the mandrel correspond to the shape and size of the bracket.

Bending the ear with round pliers. An eyelet with a thin wire core is made using round pliers. The length of the workpiece should be 10-15 mm longer than required by the drawing. Holding the workpiece at one end, the other end is bent, gradually rearranging the round-nose pliers in places of bending. After the eye is bent according to the specified size, it is given the desired shape with the help of pliers. After that, the extra end of the rod is removed with pliers.

Manual techniques are flexible, inefficient and are used when a small batch of parts is processed.

Under production conditions, metal bending is performed on bending and stretching machines of various designs. In fig. 105 shows one of these machines - a three-roller machine and the techniques for bending the profile material on this machine, and in fig. 106 shows the techniques of bending on the press.

Fig. 105. Bending of profile metal on a three-roller machine.

Pipes are bent in a manual and mechanized way in a hot and cold state with and without fillers. It depends on the diameter of the pipe, the size of the bend angle and the material of the pipes.

Bending pipes in hot condition. During hot bending with a filler, the pipe is annealed, laid out, and then one end is closed with a wooden or metal stopper. To prevent crushing, buckling and cracking when bending the pipe through the funnel, it is filled with fine, dry sand screened through a sieve, since the presence of large pebbles can lead to the pushing of the pipe wall. Weak packing leads to flattening of the pipe at the bend, therefore sand must be sealed by tapping the pipe from bottom to top. After filling with sand, the second end of the pipe should be clogged with a wooden plug, which should have holes or grooves for the gases that form when heated.

Sometimes water is used as a filler, which is frozen in a pipe.

For each pipe, depending on its diameter and material, the minimum bending radius should be set. When bending pipes, the radius of curvature is not less than three pipe diameters, and the length of the heated part depends on the bend angle and pipe diameter. If the pipe is bent at an angle of 90 °, then heat a section equal to six pipe diameters; if they are bent at an angle of 60 °, then a section equal to four pipe diameters is heated; if at an angle of 45 ° - three diameters, etc.

The length of the heated pipe section is determined by the formula

where L is the length of the heated area, mm; α - pipe bending angle, hail; d is the outer diameter of the pipe, mm; 15 is a constant factor.

When bending, the outer side of the pipe is drawn out and the inner side is compressed. Thin-walled pipes of small diameters around a cylinder of a selected size are bent without much difficulty and noticeable changes in the shape of the section. Bending pipes with a diameter of 10 mm and more requires the use of special tools.

Pipes with a diameter of 12–15 mm are bent in the fixture (Fig. 107, a), consisting of a bed 1, a movable roller 2, a roller template 3, brackets 4, a handle 5 and a clamp 6.

Fig. 107. Bending pipes:
  a - in fixture, b - manually

The smallest bending radius is determined by the radius of the rolling roller 2. The bent pipe 7 is inserted with the end into the collar, passed between the rollers, put on a piece of pipe and bend the pipe by turning the handle.

Welded pipes with a seam along the generatrix should be placed when bending so that the seam is on the side and the outside, otherwise it may diverge.

Thin-walled pipes with a diameter of 30 mm and more with a small bend radius bend only in a heated state with fillers (Fig. 107, b).

This operation is performed on pre-prepared templates. In the process of bending the pipe is checked by the place or by the pattern made of wire.

When filling the pipe with sand before bending in the end of one of the plugs, you must make a hole for the gases to escape, otherwise it may break the pipe. When bending pipes in a hot condition, they should be maintained only in mittens to avoid burns of the hands.

The pipes are heated by blowtorches in the forges or by the flame of gas burners to a cherry-red color on a length of six diameters. The fuel in the hearth can be charcoal and firewood. The best fuel is charcoal, which does not contain harmful impurities and gives a more uniform heat.

In case of overheating, the pipe should be cooled to a cherry red color before bending. It is recommended to bend the pipes from one heating, since reheating deteriorates the quality of the metal.

When heating should pay special attention to the heating of the sand. Do not allow excessive overheating of individual sections; in case of overheating, the pipe is cooled with water. From the rather heated part of the pipe, dross rebounds. After heating, the pipe is bent according to a template or copier manually.

At the end of the bending, they knock out or burn out traffic jams and pour out sand. Poor, loose pipe filling, insufficient or uneven warming up before flexing leads to wrinkling or tearing.

Bending copper and brass pipes. Cold or flexible copper or brass pipes are filled with molten rosin. The order of bending is similar to that described earlier. Rosin after bending should be melted, starting from the ends of the pipe, heating the middle of the pipe, filled with rosin, breaks the pipe.

Copper pipes, subject to bending in a cold state, need to be annealed at 600-700 ° C and cooled in water. The filler, when bending copper pipes in a cold state, is rosin, and in a heated state, sand.

Brass pipes to be cold-bend are pre-annealed at 600-700 ° C and cooled in air. Fillers are the same as when bending copper pipes.

Duralumin pipes before annealing annealed at 350-400 ° C and cooled in air.

Pipe bending mechanization. In mass production of parts from pipes, manual pipe bending devices and lever pipe bending machines are used, and for special large diameter pipe bending pipes (with a diameter of up to 350 mm), special pipe bending machines and presses are used.

Recently, new methods of pipe bending have been widely used - bending with stretching of the workpiece and bending with heating by high-frequency currents.

The first method is that the workpiece is subjected to tensile stresses exceeding the yield strength of the metal, and then in the stretched state is bent. This process is carried out on bending and stretching machines with a rotary table. The parts bent by this method have high strength and significantly lower weight. This method is used in the manufacture of pipes for aircraft, motor vehicles, sea and river vessels, etc.

When bending pipes with heating by high frequency currents, heating, bending and cooling occur continuously and consistently in a special high-frequency installation such as pipe bending machines. Installation allows the bending of pipes with a diameter of 95 to 300 mm. It consists of two parts: mechanical and electrical; the mechanical part is a machine for bending pipes, and the electrical part consists of electrical equipment and a high-frequency installation.

This method has several advantages: it provides less ovality at the bend of the pipe, high performance (4-5 times higher than other methods), the process is mechanized.

Correctly curved are pipes that have no dents, bulges and folds.

Types and causes of marriage during editing and bending

When editing, the main types of defects are dents, marks from hammer punch, nicks on the treated surface from the ribs of the hammer. These types of defects are the result of improper strikes, the use of a hammer, on which strikes there are nicks and holes.

When bending metal, scrap is most often manifested in oblique bends and mechanical damage to the machined surface, as a result of incorrect marking or fixing the part in a vice above or below the marking line, as well as improper striking.

Questions for self-test

1. How should you edit sheet, round, strip metal? What are the features of editing hardened products?
2. How do a hardened square die when warped around the inside and outside corner?
3. How to bend staples in a vice?
4. How is the pipe bending in hot condition?
5. How to determine the length of the workpiece ring diameter of 120 mm from a wire diameter of 5 mm?

  Editing and bending metal

TO   category:

Fitting and assembly work

Editing and bending metal

Edit Bending, local irregularities, bulges and dents of various shapes, waviness and other defects appear on metal-made blanks and parts after annealing, welding, cutting and other operations. The operation to correct these defects is called editing.

Manual editing of sheet metal is carried out on a plate or anvil using wooden hammers or hammers made of copper, lead, aluminum or rubber.

Billets of bar and profile steel rule steel hammers with a round convex striker. Large blanks rule blows sledgehammers or mechanical hammers and presses.

Since metal strikes on the metal inevitably leave traces, when straightening products with an already treated surface, linings made of soft materials (wood, brass, etc.) are used. Thin sheet metal (gold, silver), and also a foil correct, smoothing wooden or metal smoothins.

The most time consuming is the operation of editing sheet metal. Three cases are distinguished: straightening a wavy stripe or at the edges (Fig. 1, a), straightening curved (sickle-shaped) blanks for a ruler (Fig. 1, b) and straightening bulges.

When editing the waviness of the strip or along the edges of the workpiece, which is most often obtained when cutting it from a sheet, hammer blows are applied, starting from the most convex places to the edges of the fis. 1, a). The strongest blows are delivered in the middle and the force of the blow is reduced as it approaches the edges. Thus, the convex parts of the strip are precipitated and the waviness is leveled.

The thinner the sheet blank, the more careful and careful it is to make the edit, because if the hammer is hit improperly, its side grants can easily spoil the blank or even pierce it.

Editing of long, narrow sickle-shaped bent blanks produced on the plate under the ruler. To do this, lay the workpiece on the slab, press it to the slab with a hand and hammer (wooden or steel with a convex striker) to strike, starting from the shorter concave edge of the bent blank, i.e., where the metal fibers are compressed and need to be stretched so that the workpiece is leveled. At the beginning of the edit, the blows to the concave edge should be stronger, and as they approach the opposite edge, they become weaker and weaker. This achieves the fact that the concave, shorter edge gradually stretches and the workpiece straightens, which is controlled by a ruler (Fig. 1, b).

Fig. 1. Edit strip and sheet metal: a - edit strip on the plate; b - straightening a strip with crescent-shaped curvature; c - straightening sheet with a bulge

Fig. 2. Sequential bending of a square bar grid element on a special mandrel: c - mandrel, b - sequential bending operations

Bending By means of bending from a rectilinear blank, a curved product is obtained. Bending the workpiece produced by bending it around any mandrel, the shape of which it takes, in a vice or on the plate at the desired angle. In fig. 2 shows the mandrel and successive bending operations (1-6) of a square bar for the manufacture of a lattice element. For thick blanks, bending is carried out with blows of a hammer, preferably a wooden one, which leaves no traces of impact from the metal. Sometimes bending is done by eye or by pattern. The wire is bent with pliers or round pliers (Fig. 3).

In the process of bending, the outer layers of the metal are stretched and lengthened, while the inner ones, while being compressed, shorten. Unchanged along the Length The so-called neutral layer remains, which is symmetrically shaped along the section of blanks (square, rectangular, round, oval, hexagonal, etc.) lies at an equal distance from the sides, in the middle, and asymmetrical profiles (triangular, semicircular) neutral layer passes through the center of gravity of the section.

Fig. 3. Contemporary Jewelry

The dimensions obtained in the examples should be rounded to a larger value by pripilovka edges in size after bending.

Often the length of the workpiece indicated on the drawing; then there is no need to define it. If the bending radius is very small, then cracks may form in the metal. To avoid this, you should not bend along radii smaller than twice the thickness of the workpiece.

Sheet metal after rolling has a fibrous structure. In order to avoid cracking, it should be bent across the fibers or so that the bend line was an angle of 45 ° with the direction of rolling.

When bending sheet metal parts (and in some cases also round and square wire, strips, etc.), springing occurs, i.e., the bending angle increases slightly, and the part is straightened after stress relief. The magnitude of the angle to which the part is extended, due to the elastic recoil, depends on the degree of elasticity of the metal, its thickness and the bend radius. It is very difficult to accurately determine the angle of springback in advance, so you have to bend the workpieces more, i.e., with obviously smaller radii and bending angles, and the tooling (mandrel) to obtain accurate bends of parts must be selected and modified (adjusted) by experiment.

Billet, bar or sheet blanks for processing can be bent, crooked, warped or have bulges, waviness, etc. A plumbing operation in which such blanks or parts are given a regular geometric shape by hammer blows or press pressure are called straightening.

You can edit the billet or parts of plastic metals and alloys (steel, copper, brass, etc.). Workpieces or parts made of brittle metals cannot be ruled. They also rule blanks or parts after heat treatment, welding and soldering.

Sheet material and blanks from it can be warped at the edges and in the middle, have bends and local irregularities in the form of dents and bulges of various shapes. When considering deformed blanks, it is easy to see that their concave side is shorter than the convex one. The fibers on the convex side are stretched, and on the concave side they are compressed.

The metal undergoes editing both in a cold and in a heated state. The choice of method depends on the amount of deflection, the size of the product, as well as the nature of the material. Editing in a heated state is carried out in the temperature range of 800-1000 ° С (for Art. 3) and 350- 470 ° С (for duralumin). Above the heating is not allowed, as it can lead to a metal burnout.

Editing with heating parts up to 140-150 ° is called straightening heated.

Editing can be carried out manually - on a steel or cast-iron plate, or on an anvil and machine - on the correct rollers, presses.

Right cooker. The correct plate should be massive enough. The weight of the slab must be at least 80-150 times the weight of the hammer.

The correct slabs are made of steel or gray cast iron, monolithic or with stiffeners.

Plates come in the following sizes: 400x400; 750x1000; 1000x1500; 1500x2000; 2000x2000; 1500x3000 mm. The working surface of the plate should be smooth and clean.

Plates are installed on metal or wooden supports, which should ensure, besides stability, horizontal position.

Hammers. For editing, use hammers with a round smooth polished striker (see. Fig. 92, b).

For straightening hardened parts (straightening), hammers with square striker (weight 400-500 g) made of steel U10 are used. Well-proven hammers equipped with a hard alloy, the body of which is made of steel U7 and U8. In the working ends of the hammer insert a plate of hard alloy VK8 and VK6. The working part of the striker is sharpened and brought along the radius of 0.05-0.1 mm.

Hammers with push-in strips made of soft metals (see. Fig. 92, c). These hammers are used when editing parts with a finished surface and parts or blanks of non-ferrous metals and alloys. Plug-in dies can be copper, lead, and also wooden.

Smoothers (wooden or metal bars) are used when editing thin sheet and strip metal.

Editing technique

The curvature of the parts is checked by eye or by the gap between the plate and the part laid on it. Curved places are marked with chalk.

When editing, you need to choose the right places on which to strike. Impacts must be strong, commensurate with the value of curvature and gradually decrease as the transition from the greatest bend to the least bend. Editing is considered complete when all irregularities disappear and the part becomes straight, which can be determined by overlapping the ruler. It is necessary to edit the part on a plate or reliable linings, which exclude the possibility of a part slipping during an impact.

Editing of strip metal. Carried out in the following order. The detected bend is marked with chalk, after which the curved part is taken by the end with the left hand and placed on the slab or anvil with a convex part upwards. They take a hammer in the right hand and deliver strong blows to the greatest convexity, reducing them as the strip straightens, and finish the straightening with light blows (Fig. 101, a).

Fig. 101. Metal straightening techniques:
   a - a band, b - a sheet, c - thin sheets with hammers (mallets), d - treads

When straightening, the strip should be turned from one side to the other as necessary, and after finishing the straightening of the wide side, proceed to straightening the rib. To do this, turn the strip on the edge and deliver strong blows at first, and as the curvature is removed, it becomes weaker and weaker in the direction from the concave part to the convex part. After one or two strikes, the strip should be rotated from one edge to another.

The results of edits (straightness of the workpiece) are checked on the eye, and more precisely, on a marking plate for clearance or by applying a ruler to a strip.

The straightened material may have defects, mainly due to the incorrect determination of the place at which the blows were struck, due to the uneven force of the blow, the absence of the accuracy of the blow.

The edges of the blanks, cut on the machine, usually have warping and wavy shape. Before editing, the warped places are encircled with chalk or with a simple pencil. After that, the workpiece is placed on the slab, pressed with the left hand, and the right one is hit with a hammer in rows along the entire length of the strip, gradually moving from the bottom edge to the top. At first they strike hard, and as they move to the upper edge with less force, but more often.

Editing sheet metal. This is a more complicated operation. Convexity most often occurs on the entire surface of the sheet or is in the middle, so when you edit it, you cannot strike the convex place with a hammer, since this convexity will not only not decrease, but, on the contrary, increase even more.

Before proceeding to the editing of sheet blanks with bulges, you need to establish where the metal is more stretched, and circle the bulging places with a pencil or chalk. After that, put the workpiece on the base plate so that it lies all over the plate and its edges do not hang down. Then, supporting the sheet with the left hand, with the right hand they strike with the hammer from the edge of the sheet in the direction to the convexity, as shown by arrows in fig. 101, b. The flat part of the sheet will be stretched, and the bulge will gradually disappear. As you approach the bumps, the strikes should be applied more and more often.

While editing, it is necessary to monitor whether the surface of the sheet improves, whether traces of hammer blows remain on it and whether the bulge decreases.

Thin sheets are ruled by light wooden hammers-mallets (Fig. 101, c), copper, brass or lead hammers, and very thin sheets are laid on a flat plate and smoothed with ironers - metal or wooden bars (Fig. 101, d).

Bar Material Editing. Short rods rule on the correct slabs, striking hammering out bulges and curvatures. Eliminating the bulges, achieve straightness, striking light strikes along the entire length of the bar and turning it with his left hand. Straightness is checked on the eye or on the clearance between the plate and the bar.

Strongly springy, as well as very thick blanks rule on two prisms, striking through a soft pad to avoid nicks on the blank. If the efforts developed by the hammer are insufficient for dressing, then manual or mechanical presses are used. In this case, the workpiece mounted on the prism convex part up.

Editing heated. Profile metal (corners, channels, taverns, I-beams), hollow shafts, thick sheet steel, forgings rule with heating of a curved spot (bulge) with a blowtorch or welding torch to a cherry-red color; the surrounding convexity metal layers are cooled with raw asbestos or wet rags.

Editing (straightening) hardened parts. After quenching, steel parts sometimes warp. Editing hardened parts called straightening. The accuracy of the straightening can be achieved in the range of 0.01-0.05 mm.

Depending on the nature of the straightening, various hammers are used. When leveling precision parts on which traces of hammer blows are not permissible, use soft hammers (made of copper, lead). If, however, when straightening you have to pull out, lengthen the metal, use steel hammers weighing from 200 to 600 g with hardened striker or special straightening hammers with a rounded narrow striker side. It is better to place the part not on a flat plate, but on a trimming head.

Products with a thickness of at least 5 mm, if they are hardened not through, but only to a depth of 1-2 mm, have a viscous core, therefore, they rivet relatively easily; they need to be straightened, as raw parts, i.e. strike blow on convex places.

Products that are thinner than 5 mm are always hardened through, so they need to be straightened not by convex, but, conversely, by concave places (Fig. 102, a). The fibers of the concave part of the part are stretched, elongated from hammer blows, and the fibers of the convex part are compressed, and the part is straightened.

Fig. 102. Methods of editing (straightening):
  a - thin parts, b - an angle when the angle changes is less than 90 °, c - an angle angle when the angle changes is more than 90 °

In fig. 102, b shows the editing of a square, in which the angle between the shelves has changed after quenching. If the angle has become less than 90 °, then the blows with a hammer are applied at the top of the inner corner, if the angle has become more than 90 ° (Fig. 102, c), then the blows are applied at the top of the outer corner.

In the case of warping of the product along the plane and along the narrow edge, the straightening is performed separately - first, along the plane, and then along the edge.

Manual editing is an inefficient operation, and it is resorted to in cases where small batches of parts rule. Basically, enterprises use machine editing performed on manual rollers (Fig. 103, a), regular rollers and presses, as well as on special tools.

Fig. 103. Mechanization of edits:
  a - on manual rollers, b - regular rollers, c - rolls for varietal material; 4 - upper traverse, 2 - upper support rollers, 3 - work rolls, 4 - lower support rollers, 5 - lower traverse

The correct rollers (fig. 103, b) have rolls that rotate in different directions. The workpiece is fed into the rolls, tightened and, passing between them, straightens.

Rollers with round rollers are used for straightening sheet metal, rollers with streams along a profile of a straightened metal are used for straightening a grade material (squares, channels, etc.) (Fig. 103, c).

The correct presses are used for straightening metal up to 25 mm thick. The bar or strip is placed in the support block with a bulge up. Editing produce punch mounted on the slide, which receives movement from a mechanical or hydraulic actuator.

Chipping is a metalworking operation of cold metal cutting by means of percussion tools (hammer) and cutting tools (chisels, cross cutters). Cutting is performed in a vice or on a plate.

Fragile metals (cast iron, bronze) are cut from the edge to the middle of the workpiece to avoid chipping of its edge. When chopping viscous metals (copper, brass), the chisel cutting edge should be periodically lubricated with soap emulsion or transformer oil. To quickly and efficiently perform cutting operations, it is necessary to use only serviceable and properly sharpened cutting tools. The sharpening of the cutting tool is made on sharpeners or universal sharpening machines, and the correctness of the sharpening angles is checked with the help of templates, which are steel plates with angular cuts.

The cutting operation must be performed in protective glasses, and in its implementation in a vice - to use protective screens (nets, shields) to avoid injury to others working in the vicinity. To prevent rapid fatigability and injury to hands when chopping metal, the electric mechanic should stand steadily halfway to the left of the vice (Fig. 17a), and keep the hammer and chisel as shown in Fig. 11.6.

Felling is a laborious and difficult operation that requires large physical stresses, therefore, when it is necessary to perform a large amount of chopping work, they use means of mechanization, for example, pneumatic or electric chipping hammers.

Fig. 17

a- the position of the worker at the vice, b - methods of proper holding of the hammer and chisel when chopping

Fig. 18. The cutting of a wide metal in a vice: a - grooves with a choke-bar, b - protrusions ("scallops") with a chisel

Editing - locksmith operation to eliminate dents, warping and curvature in sheet and strip metal, as well as in blanks and finished parts. Editing can be done manually or by machine. Manual dressing is carried out with a hammer with a round, rather than square striker, leaving deep nicks on the surface of the metal upon impact with its corners. The surface of the round hammer hammer should be well polished, the blows should be applied only with the convex part of the hammer.

Editing of thin products made of steel, non-ferrous metals and alloys, as well as parts with a treated surface, is produced with hammers from soft metals (copper, lead) or from hardwood trees. Editing of the treated surfaces can be done with a conventional hammer, but at the same time a pad of soft metal is applied to the straightened product and blows are applied to it with a hammer.

Cast iron billets and parts are not subject to editing, since even with relatively weak impacts cracks may appear in them, and with strong impacts they may be partially or completely destroyed.

Flexible is a plumbing operation, as a result of which the metal billet or part is given the curved shape of the required contour. During bending, tensile and compressive forces simultaneously act on the corresponding area of ​​the workpiece: the outer layers of metal cutting located outside the bending angles will stretch and the metal fibers will be elongated; the inner layers located inside the bendable corners are compressed and the fibers of the metal are shortened; middle layers of metal located on the neutral line of the section to be bent will not be subjected to deforming effects and therefore will retain their original structure almost unchanged.

Bending of metal at small radii should be carried out taking into account the possibility of rupture of the outer layer at the site of bending due to elongation of fibers that is unacceptable for this metal.

To facilitate the operations of bending materials and blanks of thick metal, the bending area is preheated with a flame of a blowtorch or gas torch; The required heating temperature depends on the type of metal (steel, copper, aluminum) and must be at least 25% lower than the melting point of this metal.