Chopping is cutting metal and cutting grooves. Metal cutting purpose and purpose of metal cutting

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Russian Federation

Ministry of Agriculture

FSBEI HPE "Oryol State Agrarian University"

Essay

on the topic of:" Metal cutting"

Completed:

Popryadukhin Alexander Vladimirovich

Checked:

Goncharenko Vladimir Vladimirovich

1. Metal cutting

2. Modern instrument

3. Rules and techniques for cutting metal

4. Safety rules

1. Metal cutting

Metal chopping is used to divide a workpiece into parts, remove excess metal, cut out grooves, grooves, etc. in parts. Chopping is carried out using a chisel, a cross-cutting tool and a hammer.

The chisel is a steel rod with a wedge-shaped cutting edge (Fig. 71). The sharpening angle of the chisel when cutting steel workpieces should be equal to 60°, and when cutting non-ferrous metals - 35...45°.

A crosspiece is a narrow chisel designed for cutting out narrow grooves, grooves, etc. (Fig. 71, b).

When cutting workpieces, you need to stand straight, slightly turning your body relative to the vice, your right shoulder should be against the chisel striker. The chisel is held so that the striking part protrudes from the left hand by 15 ... 30 mm.

Depending on the hardness and thickness of the workpiece being processed, the force of the hammer hitting the chisel should be different.

A brush blow is used to remove small irregularities and thin chips. During a wrist strike, the hammer moves due to the movement of the hand (Fig. 72, a).

With an elbow strike, the arm bends at the elbow and the blow becomes stronger (Fig. 72, b). Using an elbow blow, excess metal is cut off and the workpieces are divided into parts.

The shoulder blow is used for cutting thick shavings, cutting rods and strips of large thickness (Fig. 72, c).

The workpieces are cut in a vice and on a stove. When cutting in a vice, the workpiece is secured in such a way that the marking mark is 1.5...2 mm below the level of the jaws. In this case, after processing, an allowance remains on the workpiece for filing the edges. The cutting edge of the chisel is placed on the surface of the jaws at an angle of 30...40° to the cutting plane (Fig. 72, d). The angle of inclination of the chisel to the edges of the jaws should be 45...60°.

When cutting on a slab, the chisel is placed vertically (Fig. 72, c) on the marking line and blows are applied. After delivering the first blow, the chisel is positioned so that half of its cutting edge is in the already cut hole, and half is on the marking line, and the second blow is applied. With this movement of the chisel along the marking line, it is easier to install it in correct position and a continuous cut is achieved.

If the thickness of the workpiece is no more than 2 mm, then the metal is cut on one side, and on the other side a plate of mild steel is placed so as not to dull the chisel on the plate. If the thickness of the workpiece is more than 2 mm, then the marking line is applied on both sides. First, they cut through the sheet on one side, about half its thickness, and then turn it over and cut it completely.

When cutting out sheet metal blanks of complex shape, initially at a distance of 1...2 mm from the marking lines, a shallow groove is cut with light hand blows on a chisel. Then, with powerful elbow blows, they chop the workpiece along the intended groove until the contour to be cut appears on its opposite side. After this, the sheet is turned over and the workpiece is finally cut out.

At enterprises, cutting is carried out by mechanics using pneumatic and electric hammers. Sheet metal blanks are cut out by stampers using presses and special dies. To process workpieces made of high-strength steels, plasma and laser cutting. metal cutting chisel crossmeisel

Metal cutting is carried out in a vice, on a plate and on an anvil using plumber's hammer, bench chisel, crossmeisel, blacksmith chisel and sledgehammer.

Metal cutting can be horizontal or vertical depending on the location of the chisel during the operation. Horizontal cutting is done in a vice. In this case, the rear edge of the chisel is installed to the plane of the vise jaws almost horizontally, at an angle of no more than 5°. Vertical cutting is done on a slab or anvil. The chisel is installed vertically, and the material to be cut is laid horizontally on the slab.

2. Modern instrument

For metal cutting, hammers weighing 400, 500, 600 and 800 g are used. The hammers are mounted on handles made of hard and tough wood (birch, maple, oak, rowan). Handles should be oval in shape, with a smooth and clean surface, without knots or cracks. The length of the handle of a hammer weighing 400-600 g is 350 mm, and that of a hammer weighing 800 g is 380-450 mm. To prevent the hammer from jumping off during operation, the end of the handle on which the hammer is mounted is wedged with wooden or metal wedges 1-3 mm thick. The wedges are placed along the major axis of the handle section. Wooden wedges are placed on glue, and metal ones are roughed up so that they do not fall out.

The working part of the chisel and the crosspiece - (5, c, d) is hardened to a length of at least 30 mm, and the head is hardened weaker than the blade (to a length of about 15-25 mm) so that when hit with a hammer it does not crumble or crack.

The rest of the chisel and crosspiece should remain soft. Chisels and crosspieces should not have cracks, caps or other defects.

The most commonly used chisels are 175 and 200 mm long with blades 20 and 25 mm wide. To cut grooves in steel and cast iron, cross-cutting tools 150-175 mm long with a blade 5-10 mm wide are used. The heads of the chisel and crosspiece are forged to a cone, which ensures the correct direction of the hammer blow and reduces the possibility of a mushroom cap forming on the head.

The sharpening angle of chisels and crossbars depends on the hardness of the metal being processed. For chopping cast iron, hard steel and hard bronze, the sharpening angle of the tool is 70°, for chopping medium and soft steel - 60°, for chopping brass, copper and zinc -45°, for chopping very soft metals (aluminum, lead) - 35- 45°.

A mechanic's tool is sharpened sharpening machines With abrasive wheels. During sharpening, the working part of the tool (blade) becomes very hot and may become loose. During tempering, the hardness of the hardening is lost and the tool becomes unsuitable for further work. To avoid this, the working part of the tool is cooled with water during sharpening. Figure 6 shows how to hold the chisel when sharpening and how to check that the angle is sharpened correctly.

3. Rules and techniques for cutting metal

The productivity and cleanliness of metal cutting depend on the correct working methods. When chopping, you need to stand steadily and straight, half-turned towards the vice. The hammer should be held by the handle at a distance of 15-20 mm from the end and applied strong blows in the center of the chisel head. You should look at the chisel blade, not at its head, otherwise the chisel blade will not go properly. The chisel should be kept at a distance of 20-25 mm from the head.

4. Safety regulations

1. Carry out cutting only with safety glasses and a protective screen installed.

2. Securely secure the workpiece in a vice.

3. Use a working tool.

4. You cannot stand behind a working comrade.

5. When finishing work, reduce the impact force.

3. Tools and devices for cutting metal

Chopping is a metalworking operation in which, using cutting tool(chisels) remove excess layers of metal from a workpiece or part or cut the workpiece into pieces.

At modern methods processing of material or workpieces, metal cutting is an auxiliary operation.

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Definition

Metal cutting is an operation that involves separating any part of a metal workpiece according to pre-applied markings. This method of processing metal workpieces is very economical, as it significantly reduces the cost of additional processing. This leads to a reduction in the cost of finished products.

Metal cutting methods

There are two ways to cut metal:

manual;
using a guillotine.

Manual method of cutting metal

This method involves the use of a chisel, a crosspiece and a hammer. The operation is performed on a steel plate or using a bench vice. It is used in single production in the absence of specialized equipment. Characterized by low quality and productivity and high labor intensity.

Cutting metal with a guillotine

Cutting metal with a guillotine is a very popular manufacturing operation. With the help of a guillotine, cuts are made in transverse and longitudinal sections and parts of simple geometric shapes, limited by straight lines, are produced. The use of this equipment allows you to make clear and precise cuts. The parts will not have any edge damage: chips, nicks or other defects along the cut line.

Equipment used

The following types of guillotines are used in industry:

manual:
pneumatic;
hydraulic;
electromechanical.

The operating principle of the equipment is as follows. The roller conveyor feeds the metal intended for processing, which is fixed by a clamping device. A massive knife, the length of which exceeds the width of the sheet being processed, is lowered to the cutting site. He creates high pressure and, thanks to this, cuts the rolled steel as evenly as possible. With this processing method, the metal does not form burrs and does not wrinkle. The equipment is equipped with a mechanical, hydraulic or pneumatic drive. During operation, preference is given to an automatic guillotine, since it has different functional settings.

One of important stages In the production of blanks and processing of rolled steel, metal cutting is carried out. An alloy is a material that is highly hard, so special equipment is needed to cut it.

The essence of metal cutting

The cutting technology consists of cutting off excess parts of metal using special tools. Used in cases where processing does not require high precision. Most often, cutting sheet metal is necessary to separate scale and inaccuracies that arose during production. The technology is also used to remove burrs and divide the source material into parts. Chopping is a metalworking operation that is performed both manually and using special devices. In the first case, chisels, hammers, and cross-sections are used. It should be noted that metal cutting is a rather difficult process, so its automation greatly simplifies cutting.

What tools are used for manual chopping?

Metal cutting is done using chisels. They are made of tool steel (U7, U8). The edge of such a tool is a blade of great hardness (not less than 53 HRC). Depending on the hardness of the metal being processed, the chisel can be sharpened at an angle of 60° (for steel), 70° (bronze, cast iron), 35-45° (for non-ferrous metals). A less acute angle when processing hard materials is necessary so that the end of the chisel maintains its resistance and does not break. The tool head, as a rule, has less hardness (so that it does not collapse when hit by a hammer). It gradually wears out and becomes deformed, so it needs to be adjusted. Under no circumstances should you work with damaged chisels, as the hammer may slip and cause injury to the worker.

Kreuzmeisel, hammers

Tools for chopping metal include such a device as a crossmeisel. This is the so-called groove chisel. Designed for making special grooves, grooves, and other holes. Its working surface has a narrower blade width. Figured grooves are made with a similar device - a groover. Hammers are used as percussion instruments. They come with both round and square sides, weight is 400-800 grams. It is the hammer that strikes the chisel (crosspiece). To ensure that its working surface is securely fixed and does not slip off the handle, special metal or wooden wedges are often used, which are driven into it. There are different methods of striking: wrist, elbow, shoulder. A brush blow is used to separate thin chips and remove small irregularities. Cutting grooves and grooves requires an elbow strike. The full swing (shoulder strike) has maximum force. It is necessary when processing thick metal.

Material cutting options

Depending on the location of the tool and the part, vertical and horizontal cutting are distinguished. The first is performed on a slab, an anvil. The part is placed on work surface horizontally and the instrument is held vertically. After striking, the blade is moved so that part of it (about half) is in the newly formed hole. This is necessary to ensure continuous cutting of metal. If the sheet thickness is more than 2 mm, markings must be applied on both sides. First, the part is processed on one side, then turned over. If the material thickness is small, it is recommended to place a sheet of mild steel under the workpiece. This will prevent the chisel from getting dull on the anvil. Horizontal cutting (bending) of metal occurs in a vice. In this case, the working tool is mounted at a very small angle to the surface being processed (almost horizontally).

Industrial scale cutting

The enterprises carry out metal cutting in the following ways: cutting with a band saw, laser, gas, abrasive cutting (with a mixture of water and abrasive material). Laser cutting of metal is based on the use of laser heat, due to which the cutting line is heated to the melting temperature. At the same time, the base material does not heat up and retains its properties. This type of processing is highly effective; the workpiece does not require any additional processing after cutting. However, this method is characterized by high equipment costs. There are also requirements for the thickness of the material - it should not exceed 20 mm. Waterjet cutting eliminates strong thermal effects on the material, the edges do not melt, and the accuracy and quality of the cut are high. Gas treatment is based on directing a stream of oxygen to the part, which burns through the metal. Variety this method- flux-oxygen technology. The method of cutting metal using a guillotine is widely used.

A very popular method of cutting alloys is the use of a guillotine. They are manual, electromechanical, hydraulic, pneumatic. When choosing a guillotine, the serial production and the thickness of the metal that needs to be cut are taken into account. Well suited for thin sheets (approx. 1 mm) manual equipment. The hydraulic drive has great power, all operations are performed at high speed. Such machines do not have much vibration, their maintenance is not difficult, and the cutting accuracy is high. Using an electromechanical drive, metal cutting up to 8 mm thick is carried out. These devices are powerful, safe, and have many additional features.

How metal is cut on a guillotine

The machine is equipped with two knives, one of which is stationary, and the second can make circular movements. The metal is fed by a roller table to the cutting site. The knife is lowered to the marked place, and the workpiece is chopped into the necessary elements. The knife is controlled through a special button. The cutting tool creates high pressure, so there are no burrs, the edges remain smooth. This type of metal cutting has many advantages. Firstly, the cost of the process is low, there are practically no residues and waste. Secondly, the quality of the resulting products is quite high. They can be immediately subjected to further technological processing - painting, drilling, etc. However, complex configurations of parts cannot be manufactured using such equipment. All modern models guillotines are equipped with a large number of electronics. This allows you to cut metal blanks in an almost fully automatic mode.

Chopping is an operation in which layers of metal are removed from a workpiece using a chisel and a plumber's hammer or the workpiece is cut into pieces.

A chisel is the simplest cutting tool in which the wedge shape is particularly clearly expressed. A bench chisel is a steel rod made of tool carbon steel (U7, U8, 7ХФ, 8ХФ). The chisel consists of three parts - working, middle and impact.

The working part 2 of the chisel is a rod with a wedge-shaped cutting part (blade 1 at the end), sharpened at a certain angle.

The striking part (striker) 4 is made tapering upward, its apex is rounded.

The middle part 3 of the chisel is held when chopping. The sharpening angle is selected depending on the hardness of the metal being processed. Recommended chisel sharpening angles (degrees) for cutting some materials are given below.

Hard materials (hard steel, bronze, cast iron) - 70

Medium hard materials (steel) - 60

Soft materials(brass, copper, titanium alloys) - 45

Aluminum alloys - 35

The chisel is made in lengths of 100, 125, 160, 200 mm, the width of the working part is 5, 10, 16 and 20 mm, respectively. The working part of the chisel at a length of 03-0.5 is hardened and tempered. After heat treatment, the cutting edge should have a hardness of HRSE 53...59, and the striker should have a hardness of HRSE 35...45.

When testing a chisel for strength and durability, it is used to cut off a strip of steel grade St6, 3 mm thick and 50 mm wide, clamped in a vice. After the test, the chisel blade should be free of dents, chipped areas and noticeable signs of dullness.

The degree of hardening of the chisel can be determined by using an old file, which is used to run along the hardened part. If the file does not remove chips from the hardened part of the chisel (only barely noticeable marks remain on it), the hardening is done well.

Hammer swing when chopping:

Chopping tools:

a - chisel; b - crossmeisel; c - groover.

Kreuzmeisel is a type of chisel. Kreutzmeisel is designed for cutting keyways, narrow grooves and recesses in hard materials. You can also use a cross-cutting machine to cut grooves when cutting large metal surfaces.

The groover is used for cutting out profile grooves: semicircular, dihedral, etc. It differs from the crossmeisel only in the shape of the cutting edge.

Mechanized cutting is carried out using pneumatic or electric chisels equipped with a set of wide and narrow chisels. For chopping, pneumatic chipping hammers are used, operating compressed air under a pressure of 5 atm with a number of blows from 1000 to 2400 per minute.

When cutting it is necessary to carry out following rules safety precautions:

1. Use only working tools:

hammers, chisels, crosspieces should not have knocked down places, rivets (hats) and cracks;

the hammer handle must be intact (without cracks or knots), made of hard and tough wood and wedged with a polished metal wedge;

The chisel and crosspiece must be sharpened to the required angle depending on the metal being processed.

2. Wear safety glasses. The cutting area should be protected with screens and shields.

To make work easier and increase productivity, mechanized tools are used. Among them, the most common is the pneumatic chipping hammer.

Chopping is a metalworking operation in which, using a cutting tool (chisel, cross-cutter or groover) and a percussion tool (machinery hammer), workpieces or parts, excess layers of metal are removed or the workpiece is cut into pieces.

Felling is carried out in cases where high precision processing is not required. The processing accuracy achieved when cutting is 0.4-0.7 mm.

Chopping is used to remove (cut down) large irregularities (roughness) from a workpiece, remove hard crust, scale, burrs, sharp corners of edges on cast and stamped parts, for cutting out keyways, lubrication grooves, for cutting cracks in parts for welding (cutting edges ), cutting off the heads of rivets when removing them, cutting holes in sheet material.

In addition, cutting is used when it is necessary from rod, strip or sheet material cut off some part.

The cutting is done in a vice, on a plate or on an anvil. When cutting, small-sized blanks and castings are secured in a chair vice. Trimming of weld defects and bosses in large parts is carried out on site.

Cutting metal with a hand chisel is a very labor-intensive and difficult operation. Therefore, it is necessary to strive to mechanize it as much as possible.

The means of mechanizing metal cutting are: replacing the cutting with an abrasive tool, as well as replacing the manual chisel with a pneumatic or electric chipper.

When starting chopping, the mechanic must prepare his workplace. Taking a chisel and a hammer out of the workbench box, he places the chisel on the workbench on the left side of the vice with the cutting edge facing him, and the hammer with right side vice with the striker pointing towards the vice.

The correct position of the mechanic's body is of great importance for cutting. When chopping, you must stand steadily at the vice, half-turning towards it; The worker’s body should be to the left of the vice axis. Left leg set half a step forward so that the axis of the foot is located at an angle of 70-75° relative to the vice. Move your right leg back a little, turning your foot at an angle of 40-45° relative to the axis of the vice.

The hammer must be taken by the handle so that the hand is at a distance of 20-30 mm from the end of the handle (Fig. 32, a). The handle is grasped with four fingers and pressed against the palm; in this case, the thumb is placed on the index finger and all fingers are squeezed tightly. Hold the chisel with your left hand, without squeezing your fingers too tightly, at a distance of 20-30 mm from the head (Fig. 32, b).

During the chopping process, the chisel should be directed at an angle of 30-35° relative to the surface being processed (Fig. 33, a). At a smaller angle of inclination, it will slide rather than cut (Fig. 33, b), and at a larger angle, it will go too deep into the metal and produce large processing unevenness (Fig. 33, d).

Essential to the process manual cutting in a vice also has correct installation chisels in relation to the vertical plane of the fixed jaw of the vice. The normal setting of the cutting edge of the chisel should be considered an angle of 40-45° (Fig. 34, a). At a smaller angle, the cutting area increases, the cutting becomes heavier, and the process slows down (Fig. 34, b). At a larger angle, the chips, curling,

Creates additional shear resistance, the cut surface is rough and torn; it is possible to shift the workpiece in the vice (Fig. 34, c).

The quality of the cut depends on the type of swing and hammer blow. There are blows of the hand, elbow and shoulder. In a wrist swing, hammer blows are made with the force of the hand. This blow is used for light work to remove thin chips or when removing small irregularities. With an elbow strike, the arm bends at the elbow, resulting in a more powerful blow. The elbow strike is used in ordinary cutting, when it is necessary to remove a layer of metal of medium thickness, or when cutting grooves and grooves. With a shoulder strike, the swing is greatest, and the blow is the strongest. The shoulder blow is used when chopping thick metal, when removing large layers in one pass, cutting metal and processing large planes.

When chopping using a wrist blow, the average is 40-50 blows per minute; with heavier work and shoulder impact, the cutting rate is reduced to 30-35 beats per minute.

The impact of the hammer on the chisel should be as precise as possible. It is necessary that the center of the hammer striker falls into the center of the chisel head, and that the hammer handle and chisel form a right angle. You can chop only with a sharply sharpened chisel; a blunt chisel slips from the surface, this quickly tires the hand and, as a result, the correctness of the blow is lost.

The size of the chips removed by a chisel depends on the physical strength of the worker, the size of the chisel, the weight of the hammer and the hardness of the metal being processed. The most productive is considered to be cutting, in which a layer of metal 1.5-2 mm thick is removed in one pass. When removing a layer of greater thickness, the mechanic quickly gets tired, and the cutting surface turns out to be unclean.

Chopping brittle metals (cast iron, bronze) should be done from the edge to the middle of the workpiece to avoid chipping off the edge of the part. When cutting tough metals (mild steel, copper, brass), it is recommended to periodically wet the cutting edge of the chisel machine oil or soap emulsion.

Chopping in a vice can be done at the level of the jaws of the vice or above this level - at the marked marks. According to the level of the jaws of the vice, they most often cut thin metal, and above the level there are wide surfaces of the workpiece.

When chopping wide surfaces, you should use a cross-cutting tool and a chisel to reduce time. First, grooves are cut with a cross-section, and then the resulting protrusions are cut off with a chisel.

To perform chopping correctly, you need to have good command of the chisel and hammer, that is, hold the chisel and hammer correctly, without slipping, and correctly swing and hit the head of the chisel with the hammer.

Sections

Chopping is cutting metal and cutting grooves. Metal cutting purpose and purpose of metal cutting

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Similar documents

Definition

Metal cutting methods

Manual method of cutting metal

Cutting metal with a guillotine

Equipment used

The essence of metal cutting

What tools are used for manual chopping?

Kreuzmeisel, hammers

Material cutting options

Industrial scale cutting

How metal is cut on a guillotine