What blow is used to cut off excess metal? Metal cutting. The working principle of metal cutting

27.11.2019

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

The essence of metal cutting

Cutting technology involves cutting off excess metal parts 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 for removing burrs, dividing into parts source material. 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 from 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). Less sharp corner during processing hard materials necessary so that the end of the chisel maintains its strength 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. As percussion instrument hammers are used. 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 metal cutting. 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 under the workpiece mild steel. 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

At enterprises, metal is cut using the following methods: 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 processing is highly efficient, the workpiece after cutting does not require any additional processing. 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. For thin sheets(about 1 mm) fits well 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 necessary elements. The knife is controlled through a special button. The cutting tool creates a lot of pressure, so there are no burrs and 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.

TO category:

Metal cutting

General concepts about logging in plumbing

Felling is the processing of metal with cutting and impact tools, as a result of which excess layers of metal are removed (cut down, cut down) or metal intended for further processing and use is cut into pieces. As cutting tool in plumbing, a chisel or kreidmeisel is usually used, and simple or pneumatic hammers are used as impact tools.

Using chopping you can do:
— removal (cutting down) of excess metal layers from the surfaces of workpieces;
- leveling uneven and rough surfaces;
— removal of hard crust and scale;
— cutting off edges and burrs on forged and cast workpieces;
— chopping off the protruding edges of sheet material, ends of strips and corners after assembly;
— cutting into pieces sheet and varietal material;
- cutting out holes in sheet material along the intended contours;
— cutting edges into a joint for welding;
— cutting off the heads of rivets when removing them;
— cutting out lubrication grooves and keyways.

The cutting is done in a vice, on a plate or on an anvil; Bulky parts can be processed by cutting at their location. A chair vice is best for chopping; It is not recommended to cut on a parallel vice, since their main parts - jaws made of gray cast iron - often cannot withstand strong impacts and break.

The part being processed by cutting must be motionless. Therefore, small parts are clamped in a vice, and large parts are placed on a workbench, plate or anvil, or placed on the floor and well strengthened. Regardless of where the cutting is done, the height of the parts must be installed in accordance with the height of the worker.

When starting to cut, the mechanic first of all prepares his workplace. Taking the chisel and 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 on the right side of the vice with the striker pointing towards the vice.

When chopping, you must stand straight and steady at the vice, so that the body is to the left of the axis of the vice.

Rice. 1. Chopping technique: a - elbow swing, b - shoulder swing, c - correct position legs of the person working when chopping, g - holding the chisel

The left leg is placed half a step forward, and the right leg, which serves as the main support, is slightly set back, spreading the feet at an angle approximately as shown in Fig. 1, c.

Hold the chisel in your hands as shown in Fig. 1, g, freely, without excessive clamping. During chopping, they look at the working part of the chisel, more precisely, at the place of chopping, and not at the striking part, which is hit with a hammer. You only need to chop with a sharply sharpened chisel; a blunt chisel slips from the surface being cut, the hand quickly gets tired of this, and as a result the correctness of the blow is lost.

The depth and width of the layer of metal (chisels) removed by a chisel depend 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 hammer is selected by weight, the size of the chisel is selected by the length of its cutting edge. For every millimeter of chisel cutting edge length, 40 g of hammer weight is required. Hammers weighing 600 g are usually used for chopping.

Depending on the order of operations, felling can be roughing or finishing. When roughing, with strong blows of a hammer, a layer of metal with a thickness of 1.5 to 2 mm is removed in one pass. When finishing cutting, a layer of metal with a thickness of 0.5 to 1.0 mm is removed per pass, applying lighter blows.

To obtain a clean and smooth surface It is recommended to wet the chisel when cutting steel and copper machine oil or soapy water; Cast iron should be cut without lubrication. Brittle metals (cast iron, bronze) must be cut from the edge to the middle. In all cases, when approaching the edge of a part, you should not cut the surface to the end; you should leave 15-20 mm to continue cutting on the opposite side. This prevents chipping and chipping of the corners and edges of the workpiece. At the end of chopping metal, as a rule, you need to release the hammer blow on the chisel.

Chopping in a vice is done either at the level of the jaws of the vice, or above this level - at the intended risks. At the vise level, thin strip or sheet metal is most often cut; above the vise level (according to the risks), wide surfaces of workpieces are cut.

When cutting wide surfaces, you should use a cross-cutting tool and a chisel to speed up the work. First, cut grooves of the required depth with a cross-section, and the distance between them should be equal to 1D of the length of the cutting edge of the chisel. The resulting protrusions are cut off with a chisel.

To properly chop, you need to be good at using a chisel and a hammer: this means holding the chisel and hammer correctly, moving your hand, elbow and shoulder correctly, and hitting the chisel with the hammer accurately, without missing a beat.

division of metal shavings, which represents the essence of the cutting process.

The tool used for chopping, the chisel, is the simplest cutting tool in which the wedge is especially clearly defined. The wedge, as the basis of any cutting tool, must be strong and correct in shape - it must have front and back edges, a cutting edge and a sharpening angle.

The front and rear faces of the wedge are two generatrix planes that intersect each other at a certain angle. The edge that faces outward during operation and along which the chips flow is called the front; the edge facing the object being processed is the rear.

The cutting edge is the sharp edge of the tool formed by the intersection of the front and rear edges. The surface that is formed on the workpiece directly by the cutting edge of the tool is called the cutting surface.

Normal cutting conditions are ensured by the presence of rake and back angles on the cutting tool.

In Fig. Figure 2 shows the angles of the cutting tool.

The rake angle is the angle that is between the front edge of the wedge and the plane perpendicular to the cutting surface; denoted by the letter g (gamma).

Rear angle - the angle formed by the rear edge of the wedge and the cutting surface; denoted by the letter a (alpha).

Point angle - the angle between the front and rear edges of the wedge; denoted by the letter p (beta). The division of the metal layer from the rest of its mass occurs as follows. The wedge-shaped steel body of the cutting tool, under the influence of a certain force, presses on the metal and, compressing it, first displaces and then chips off metal particles. Previously broken off particles are replaced by new ones and move up along the front edge of the wedge, forming chips.

Rice. 2. Cutting patterns and cutting tool angles

Chip particles are sheared along the shear plane MN, located at an angle to the front edge of the wedge. The angle between the shearing plane and the direction of movement of the tool is called the shearing angle.

Let's consider the effect of a wedge when operating a simple planing cutter (Fig. 3). Let's assume that a certain layer of metal needs to be removed from workpiece A using a cutter. To do this, install a cutter on the machine so that it cuts the metal to a given depth, and under the action of a certain force P, it is given continuous movement in the direction shown by the arrow.

A cutter made of a rectangular bar, devoid of wedge corners, does not separate the chips from the metal. It crushes and crushes the layer being removed, tears and damages the treated surface. It is clear that such a tool cannot be used.

In Fig. 54 shows a cutter with a working part sharpened in the shape of a wedge. The cutter easily separates the chips from the rest of the metal, and the chips flow freely along the cutter, leaving a smooth machined surface.

Chisel. A metalworking chisel is a percussion cutting tool used in cutting metals. In Fig. 55, and a drawing of a chisel is given. The end of the working part of the chisel has a wedge-shaped shape, which is created by sharpening two symmetrical surfaces at a certain angle. These surfaces of the working part are called the faces of the chisel. The edges at the intersection form a sharp edge called the cutting edge of the chisel.

The edge along which the chips flow when cutting is called the front, and the edge facing the surface being processed is called the back. The angle a formed by the edges of the chisel is called the sharpening angle. The sharpening angle of the chisel is selected depending on the hardness of the metal being processed. For hard and brittle metals, the angle a must be greater than for soft and viscous metals: for cast iron and bronze, the angle a is 70°, for steel - 60°, copper and brass - 45°, aluminum and zinc - 35°, medium shape The part of the chisel is such that it allows you to hold it comfortably and firmly in your hand while chopping. The sides of the chisel should have rounded and smooth edges.

Rice. 3. Cutter during the cutting process: L - product, 1 - cutter, 2 - depth of the layer being removed, P - force acting during cutting

The striking part of the chisel has the shape of a truncated cone irregular shape with a semicircular upper base. With this form of the striking part, the force of hitting the chisel with a hammer is used with best result, since the blow always falls in the center of the striking part.

Rice. 4. Chisel (a) and cross-section (b) Dimensions of chisels in mm

When chopping metal, the chisel is held in the left hand by the middle part, loosely clasping it with all fingers so that thumb lay on the index (Fig. 56) or on the middle, if forefinger is in an extended position. The distance from the hand to the striking part of the chisel must be at least 25 mm.

Rice. 5. Position of the chisel when cutting: a - cutting at the level of the vice, 6 - cutting at the risk

Rice. 6. Installing the chisel on the workpiece in relation to the jaws of the vice

For chopping, the chisel is placed on the workpiece, as a rule, with the back edge inclined to the workpiece surface at an angle, but not more than 5°. With such an inclination of the rear face, the angle of inclination of the chisel (its axis) will be the sum of the rear angle and half the sharpening angle. For example, with a sharpening angle of 70°, the tilt angle will be 5 + 35°, i.e. 40°. In relation to the line of the jaws of the vice, the chisel is set at an angle of 45°.

Correct installation chisel contributes complete transformation impact force with a hammer into cutting work with minimal fatigue of the worker. In practice, the angle of the chisel is not measured, but the correct angle is felt to work, especially with proper skill. If the angle of inclination is too large, the chisel cuts deep into the metal and moves forward slowly; if the angle of inclination is small, the chisel tends to break out of the metal and slide off its surface.

The inclination of the chisel to the surface being processed and relative to the jaws of the vice is directed by the movement of the left hand during chopping.

Kreuzmeisel. The Kreutzmeisel is essentially a chisel that has a narrow blade. It is used for cutting narrow grooves and keyways. The sharpening angles of the crossmeissel are the same as those of a chisel. Sometimes the crossmeisel is used instead of a chisel, for example, when the chisel is too wide for the cutting edge or when the working conditions make it inconvenient to use.

Rice. 7. Sharpening a chisel (crossmeisel) on a sharpening machine and a template for checking the correct sharpening

To cut semicircular, sharp and other grooves, specially shaped crosscuts, called groovers, are used.

Sharpening chisels and crosspieces. During the operation of the chisel and cross-section, abrasion of their edges occurs, a small break in the cutting edge and a rounding of the tip of the sharpening angle. The cutting edge loses its sharpness, and further work with the tool becomes ineffective and sometimes impossible. The performance of a dull tool is restored by sharpening.

The chisel is sharpened on a grinding wheel - on a sharpening machine. Taking the chisel in your hands, as shown in Fig. 7, place it on the rotating circle and, with light pressure, slowly move it left and right across the entire width of the circle. During sharpening, the chisel is rotated first with one edge and then with the other, sharpening them alternately. You cannot press the chisel hard on the wheel, as this can lead to severe overheating of the tool and its working part losing its original hardness.

At the end of sharpening, remove the burrs from the cutting edge of the chisel by carefully and alternately placing the edges on the rotating grinding wheel. After sharpening, the cutting edge of the chisel is set on an abrasive stone.

The chisel can be sharpened with a supply of coolant and on a dry wheel. In this case, it is necessary to cool the chisel being sharpened by lifting it from the wheel and lowering it into water.

When sharpening a chisel, you need to carefully ensure that the cutting edge is straight and the edges are flat, with equal angles of inclination; The sharpening angle must correspond to the hardness of the metal being processed. The sharpening angle during sharpening is checked with a template.

The crossmeisel is sharpened in the same way as a chisel.

Locksmith's hammers. It was already indicated earlier that in plumbing two types of hammers are used - with a round and square striker. The end of the hammer opposite the striker is called the toe. The toe is wedge-shaped and rounded at the end. It is used for riveting, straightening and drawing out metal. During chopping, the chisel or cross-meisel is hit only with the hammer head.

Ways to hold a hammer. The hammer is held by the handle in the right hand at a distance of 15-30 mm from the end of the handle. The latter is grasped with four fingers and pressed against the palm; The thumb is placed on the index finger, all fingers are squeezed tightly. They remain in this position both during the swing and during the impact. This method is called “holding the hammer without unclenching your fingers” (Fig. 9, a).

Rice. 8. Bench hammers: a - with a round striker, b - with a square striker, c - jamming of the hammer on the handle

There is another method that involves two steps. With this method, at the beginning of the swing, when the hand moves upward, the hammer handle is clasped with all fingers. Subsequently, as the hand rises up, the clenched little finger, ring finger and middle fingers gradually unclench and support the hammer tilted back (Fig. 9, b). The hammer is then given a push. To do this, first clench the unclenched fingers, then accelerate the movement of the entire arm and hand. The result is a strong hammer blow.

Rice. 9. Methods of holding a hammer when chopping: a - without unclenching your fingers, b - with unclenching your fingers

Hammer blows. When chopping, hammer blows can be made with a wrist, elbow or shoulder swing.

The wrist swing is carried out by moving only the hand.

The elbow swing is made by the elbow movement of the arm - bending it and then quickly extending it. During an elbow swing, the fingers of the hand act, which open and close, the hand (moving it up and then down) and the forearm. To receive a strong blow, the extension movement of the arms must be done quickly enough. Exercises in the elbow swing develop well the elbow joint along with the hand and fingers.

The shoulder swing is a full arm swing that involves the shoulder, forearm and hand.

The use of this or that swing is determined by the nature of the work. The thicker layers of metal are removed from the surface being processed, the greater the need to increase the impact force, and therefore, to increase the swing; However, if you use a wide swing incorrectly, you can damage the workpiece and tool and tire unnecessarily quickly. You need to learn to accurately balance the impact force according to the nature of the work being performed.

The hammer should strike the chisel with an elbow swing with the fingers unclenched; with such a blow you can chop for quite a long time without getting tired. The blows must be measured, well-aimed and strong.

The productivity of the cutting depends on the force of the hammer applied to the chisel and on the number of blows per minute. When chopping in a vice, make from 30 to 60 strokes per minute.

The force of the blow is determined by the weight of the hammer (the heavier the hammer, the stronger the blow), the length of the hammer handle (the longer the handle, the stronger the blow), the length of the worker’s arm and the length of the hammer swing (the longer the arm and the higher the swing, the stronger the blow).

When chopping, you must use both hands in concert. Right hand you need to accurately and accurately hit the chisel with a hammer, and with your left hand, in the intervals between blows, move the chisel along the metal.

Cutting is a metalworking operation in which, using a cutting tool, excess layers of metal are removed from a workpiece or part or the workpiece is cut into pieces. At modern ways processing of material or workpieces, metal cutting is an auxiliary operation.

Metal cutting is carried out in a vice, on a plate and on an anvil using a metalworker's hammer, a chisel, a cross-cutting tool, a blacksmith's chisel and a sledgehammer.

Metal cutting can be horizontal or vertical depending on the location of the chisel during the operation. When horizontal cutting is done in a vice, the back edge of the chisel is set to the plane of the vice jaws almost horizontally, at an angle of no more than 5°C. 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.

Rice. 3. Parallel vice:

1 - worm screw, 2, 3 - movable and fixed jaws, 4 - turntable,

5 - turntable screw, 6 - bottom plate

Rice. 4. Chair vice:

1 - lever, 2,3 - movable and fixed jaws, 4 - bushing, 5 - spring, 6 - paw, 7 - spacer sleeve

Hammers with round heads are used when required great strength and accuracy of impact, and with square ones - for easier work. Hammers are made from U7 tool steel. The working parts of the hammer are hardened and tempered. The hammer must be in good condition, without cracks, caps, cavities and other defects.

The working part of the chisel and the crosspiece ( , e, d) is hardened to a length of at least 30 mm, and the head - weaker than the blade (about 15-25 mm in length) 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.

Rice. 5. Tool for chopping: a - a mechanic’s hammer with a round striker, b - a mechanic’s hammer with a square striker, c - a chisel, d - a crosspiece

Rice. 6. Sharpening a chisel on a sharpening machine: a - Techniques for holding the chisel when sharpening, b - a template for checking the correct sharpening angle

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, cutters 150-175 mm long with a blade 5-10 mm wide are used. The heads of the chisel and kreitzmeisel are forged onto a cone, which ensures the correct direction of the hammer blow and reduces the possibility of the formation of a mushroom cap 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 tempered. 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. In Fig. 6 shows how to hold the chisel when sharpening and how to check that the angle is sharpened correctly,

Metal processing involves several operations, one of which is cutting. In this case, the workpiece is divided into more convenient pieces, preceding the cutting process. The following discusses in detail the methods by which metal is cut, possible problems, the difference between mechanical and manual operation and types of equipment used.

Metal cutting is a metalworking operation involving the impact of a cutting or impact tool on a metal workpiece. The process allows you to divide it into parts, get rid of excess layers of material, and also obtain grooves and grooves. The cutting tool for chopping metal is a cross-cutting tool or a chisel, and the impact tool is a hammer. The latter is always used when handmade, and the first two - depending on the desired result.

The chisel is designed for rough work and cutting off burrs. It consists of 3 parts:

worker (carries out cutting);
middle (the master holds the chisel by it);
percussion (it is hit with a hammer).

Kreutzmeisel - a tool for cutting out grooves and narrow grooves; for wide ones, a modified device with a different cutting edge shape (“groove”) is used.

Manual processing of workpieces in production is an energy-consuming and low-productivity process. Often it is replaced with a mechanical one.

The sequence of cutting metal with a chisel is as follows:

the workpiece is placed on a plate or anvil, or better yet, secured in a vice;
the chisel is placed vertically on the marking line (cutting point);
light blows are applied along the contour with a hammer;
This is followed by deep cutting along the revealed contour;
the workpiece is turned over;
strikes with a chisel are made from the other side until the cutting is completed.

It is important to leave a small portion of the blade in the cut groove so that the process is accurate. Now - a few words about the problems that arise during manual cutting of metal.

Possible defects

Manual cutting metal is bad in that there is a possibility of damage to the workpiece, although the entire process was strictly controlled. Below are common defects and their causes.

Curvilinearity of the cut edge (weak fastening of the part in the vice).
The edge is “torn” (the blows were carried out with a dull chisel or an incorrectly sharpened crosspiece).
The parallelism of the sides of the product is broken (misalignment of the marks or the workpiece in a vice).
The depth of the grooves varies along the length (the angle of the crosspiece was not adjusted; the impact was uneven).
The appearance of nicks on the part (dull chisel).
The presence of chips on the edge of the part or inside the groove (the chamfer was not removed from the workpiece).

To avoid the problems listed above and not to damage the metal template for work, it is recommended to follow a number of rules:

securely fasten the part if possible;
keep the chisel angle at least 30 degrees;
accurately mark the workpiece;
work only with sharpened chisels and cross-cutting tools, and monitor their angle of inclination;
before work, chamfer the part;
strike evenly.

Manual cutting sheet metal was the only way to work about 50 years ago. Today, craftsmen have access to equipment that requires them only timely control, working accurately, efficiently and without damage to the workpiece.

Guillotine machines for cutting metal

Any enterprise engaged in the production or production of rolled metal products is equipped special equipment. The advantages of its implementation are obvious:

labor productivity is growing;
personnel safety is ensured;
processing of materials becomes better.

The most well-known machine for chopping metal in a manufacturing environment is known as a “guillotine.” It happens:

manual;
mechanical;
hydraulic.

The first is a compact device for local work. It cuts sheet metal of small thickness (up to 0.5 mm) and is driven by human effort. Application manual machine for cutting reinforcement, iron, steel and other products, it is more effective than working with a chisel or cross-cutting machine, but labor productivity will still be low. The reason is the need for human effort.

The mechanical guillotine is equipped with a foot drive. Its dimensions are impressive, and the permissible thickness of materials for cutting has been increased to 0.7 mm. By using the strength of the legs rather than the arms, productivity increases by several percent.

A special feature is the hydraulic guillotine, which operates autonomously and does not require human intervention. Equipped with a control unit in which up to a dozen parameters are set (type of metal, cutting angle, etc.). The permissible thickness of the workpiece varies depending on the model and reaches several millimeters.

The listed types of metal cutting are complemented by equipment that is structurally different from guillotines and has an expanded scope of application.

Features of combined devices

The equipment includes press shears and angle cutting machines.

The first ones chop and cut strip, sheet, shaped and long products. Press shears are indispensable for punching holes in workpieces and cutting open grooves. These combined cutting machines can handle any profile (channel, angle, T/I-beam, circle, square and others).

Angle notching machines are also called notching dies. They are distinguished by:

simplicity of design;
high work productivity;
increased accuracy of output products.

Used for corner processing of any materials. Compact design includes a measuring scale and chisels for cutting. The stamp for the process is selected depending on the thickness of the sheets.

Some tools used in metal cutting combine manual and mechanized labor. These include:

pneumatic and electric chipping hammers;
special machines where standard techniques Chisel cutting is accelerated 5-10 times thanks to the use of special devices.

To give you a clear idea of the characteristics of the devices, let’s look at one example below. In particular, a machine for cutting reinforcement SMZH 172.

Device Features

The SMZH 172 machine is designed for cutting reinforcing steel, strips, metal profiles with a maximum permissible tensile strength of 470 MPa. Has several modifications:

SMZh-172 A (continuous knife stroke);
SMZh-172 BAM (continuous and single stroke).

The sawing machine for fittings SMZH 172 has the following technical characteristics:

power - 3 kW;
diameter of cut reinforcement - up to 40 mm;
strip dimensions - 40x12 mm;
cutting squares with sides up to 36 mm;
speed of the scenes - 33 rpm (9 rpm - for a single stroke);
maximum force - 350 kN;
weight - 430/450 kg.

The design of the machine for cutting reinforcement smzh 172 is complemented by an adjustable stop with rack gearing, which allows you to obtain an even perpendicular cut.

The advantages of using the equipment are:

the ability to replace consumables (blades) at the workplace without the help of special stands;
long-term storage of the machine is permissible if it is not in use (in accordance with the manufacturer’s recommendations);
ease of disassembling the mechanism in order to adjust parameters.

The machine is unique, because it can work both autonomously (continuous movement of the chisel) and right moment(single stroke when pressing the handle). Guillotine cutting, for example, does not yet have such functionality. You can see the operation of the SMZH 172 machine in the video below.

Video: Manual cutting of metal on the SMZH 172 machine.

Cutting metal blanks is one of the main production processes. Hard human labor is being replaced by machine labor, and this is worth taking advantage of. The listed tools for chopping materials cope with different workpieces. It is only important to choose the right equipment.

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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. By moving the chisel along the marking mark in this way, it is easier to install it in the correct position and ensures a continuous cut.

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 blanks from sheet metal complex shape Initially, at a distance of 1...2 mm from the marking lines, a shallow groove is cut with light wrist blows on the 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 a metalworker's hammer, a chisel, a cross-cutting tool, a blacksmith's chisel and a 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. 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°.

Tools are sharpened on sharpening machines with abrasive wheels. During sharpening, the working part of the tool (blade) becomes very hot and may become tempered. 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 correct work techniques. 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 a cutting tool (chisel), excess layers of metal are removed from a workpiece or part or the workpiece is cut into pieces.

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

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