Metal cutting mechanization

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Metal cutting

Metal cutting mechanization

Manual cutting is being replaced by processing on metal-cutting machines (planing, milling), processing with abrasive tools, and the use of hand mechanized tools and devices.

Rice. 1. Processing wide surfaces chopping:

Rice. 2. Cutting out lubrication grooves (a) and grooves (b) a - aligning the grooves with a cross-section, 6 - cutting off the protrusions with a chisel

Rice. 3. Pneumatic chipping hammer RM-5

Hand-held power tools include pneumatic and electric chipping hammers. In Fig. Figure 3 shows the device of the pneumatic chipping hammer RM-5 from the Pnevmatika plant. The hammer consists of a body, a striker, a spool and a handle with a trigger. Compressed air from the workshop line passes through a rubber hose and fitting to the hammer handle. Locksmith takes right hand by the handle, with the left hand he holds the Barrel, directing the movement of the chisel.

When you press the trigger, the valve opens and air is pressurized 5 -6. kgf/cm2 from the line through the fitting enters the cylinder. Depending on the position of the spool, air enters the working stroke chamber or the return stroke chamber through channels inside the housing. In the first case, the air pushes the striker to the right and it hits the shank of the working tool. At the end of the working stroke, the spool is displaced by air pressure, air enters the chamber - the reverse stroke. Then the work cycle is repeated. The hammer is put into operation after the cutting edge of the tool has been pressed onto the surface being processed.

Special chisels are used as a tool for chopping with a pneumatic hammer. Cutting performance during use power tool increases by 4-5 times. In Fig. 78, a, b shows work with a pneumatic hammer.

Rice. 4. Techniques for working with a chipping hammer: a - holding the tool, b - moment of operation

Rice. 5. Safety devices used when cutting: a, b - safety shields, c - safety washer

In electric hammers, the rotation of the electric motor shaft mounted in the housing is converted into a reciprocating movement of the striker, at the end of which a chisel or other tool is attached.

Safety.

When cutting metals, you should do following rules occupational safety:
– the handle of a hand hammer must be well secured and free of cracks;
– when cutting with a chisel and cross-cutting tool, you must use safety glasses;
– when cutting hard and brittle metal, be sure to use a fence: mesh, shield;
– to protect hands from damage (when uncomfortable work, as well as during the training period), a safety rubber washer should be put on the chisel, and a safety visor should be put on the hand.

When working with a pneumatic hammer you must:
1) before starting to work with a pneumatic hammer, study the safety rules: repeat general techniques and methods for preparing pneumatic tools;
2) wipe the sleeve hole and the chisel shank; check the position of the bushing, which should be tightly seated in the hole, and then install a chisel with a tight fit into the bushing;
3) blow out compressed air pneumatic hammer;
4) pour lubricant through a special hole into the hammer body, press the trigger and introduce lubricant through the open hole into the internal working parts;
5) put on gloves and safety glasses; take a working position; take the handle with your right hand, placing thumb pull the trigger and grasp the hammer body with your left hand;
6) when cutting, place the chisel at an angle of 30 - 35° relative to the surface being processed. Chopping should only be done with a sharply sharpened chisel;
7) include pneumatic tool only after installing the tool in working position; idling tools are not allowed,
8) when connecting the hose, the compressed air must be turned off;
9) you cannot hold the pneumatic hammer by the hose or working tool;
10) when carrying a pneumatic hammer, do not allow tension, looping or twisting of the hose;
11) after finishing the work, turn off the valve on the pipeline and disconnect the pneumatic hammer from the air line, remove the working tool, clean the hammer from dust, dirt and wipe it; carefully wind the hose.

The serviceability of a pneumatic tool is the basis for its high-performance and safe use. You can preserve the tool for a long time and always have it in working condition only if you carefully follow the rules of operation and storage.

First of all, you should make sure that the tool is in good working order, that is, check whether all the screws securing individual components and parts are tightened sufficiently. The air hose needs to be checked; it should not have cracks or punctures. Before attaching the hose to a pneumatic tool, it is thoroughly blown with compressed air to remove dust and dirt, which, if trapped inside the tool, contribute to its wear. Then you should check the lubrication of the tool. Lubricant should not get on the hose, as it causes its damage. It is also necessary to check the serviceability of the insertion tool (chisel, crosspiece, groover, etc.) and the reliability of its shank.

A pneumatic tool must be held firmly and confidently in your hands. First, it is recommended to test the instrument in operation by turning the air on and off 2-3 times. If the instrument does not detect any abnormalities, it can be turned on to perform the required operation. Kinks in the hose are not allowed, as this will lead to a drop in pressure. Do not allow carts or cars to run over the hose, as this will quickly damage the hose. It is not recommended to tighten the hose as this may cause rupture at the connections.

Continuous heavy use will cause the insert tool to become hot, which may cause the shank to seize. A hot insertion tool should be replaced with another one. During short breaks in work, pneumatic tools must be placed in a clean place. During a long break in work, you need to close the air valve on the line, disconnect the tool from the hose, remove the insert tool and put it in the storeroom. Pneumatic tools should only be stored in a dry, heated room.

During thinning the ELHA unit can be used in apiaries 30-40 m wide. Skidding sights are laid at an angle to the technological corridor of 60 0 and trees are cut down onto it with an electric saw. The branches are cut off with it. The whips are skidded over the tops.

Promising variants of the “Dyatlov” could also be used. In 1984, at an exhibition in Moscow, a sample of the MVP-20 was exhibited on a self-propelled chassis with a 6-meter reach of the manipulator, cutting trees up to 22 cm. The high-performance version “Woodpecker-1D” has a trunk storage device on the boom.

Since the “Woodpeckers” only lay the trees on the skid, for their skidding they used the “Ant” bundle skidder, which was aggregated with the T-40A, MTZ-52 tractor and other narrow machines with four driving wheels. The skidder is an arrow that lifts a bunch of trees (wisps) by the butt.

In through-cutting, when selecting large-sized trees, the woodpecker-2 (LP-2) feller-buncher machine was used, created on the basis of the TDT-55 tractor with a second cabin on a turntable and a boom 10.5 m long, with a gripper and console saw. In its development, the MVP-35 machine was designed with one cabin and a storage unit on the boom. The drive can accommodate 8 trees with a trunk diameter of 8-14 cm. The LP-54 machine, based on the TT-4 tractor with a manipulator boom reach of 10 m, was being prepared for production.

During thinning and through cuttings, a wide-apiary technology of logging work with technological corridors laid every 60-100 m is promoted. Trees, logs (half-lengths), assortments are hauled to them using a winch LT-100, LT-400, LT-600, ML-2000M or skidder tractor PDT-1, PDT-0.3. For example, the LT-400 winch is installed on a two-wheeled trolley, has a 65 m long cable and a base engine from a chainsaw, weighs 76 kg, and is operated by two people. Small whips are skidded in packs up to 0.4 m 3 using drags or chokers. Productivity with an average log diameter of 10 cm is 12-14 m3. Tractor skidder PDT-0.3, in addition to a winch with a cable 65 m long, has a hydraulic manipulator for transporting cleared wood along the drag.

Wide-grazing technology is especially recommended in forests with a dense network of roads that are used as technological corridors. In Ukraine, a thinning technology with a delimbing and crosscutting machine has been developed. Technological corridors 4 m wide are laid across crop rows every 80 m. Trees are felled with a chainsaw for skidding by the butt along the rows with a winch to a unit based on MTZ-82. Trees with a maximum butt diameter of 35 cm are processed. The assortments have a length from 1.5 to 6.0 m (multiples of 1.5) and are skidded by another machine.

The most common technology for mechanized thinning and through-cutting is medium apiary (width - 31-50 m) with felling of trunks with a chainsaw and skidding of trees or sticks by the tops with agricultural wheeled tractors equipped with a winch and shield, or skidding device LTP-2, LTN-1. Tractors T-5L, T-40A, T-25, MTZ-52, TL-28, etc. have proven themselves well. In areas where there are no technological corridors, technological corridors are prepared with a width of 2-3 m. More powerful tractors are also used: MTZ -82, MTZ-80 (with a factory skidding winch), LKT-80 and the TDT-55A tracked skidder, for which a 4-5 m wide drag is being prepared. The UTG-4.8 hydraulic grab can be installed on the MTZ-82 (80) .

Operating experience since 1982 of the forest wheeled tractor LKT-80 produced by Czechoslovakia has confirmed the possibility of developing a stable running system in the forest. Preparing for serial production in CIS countries wheeled skidder LT-19, equipped with a hydraulic manipulator for collecting the whips by the tops or butts using a hydraulic clamp. Its productivity at a skidding distance of 300 m is 38 m 3 per shift. It is planned to create a set of machines based on a caterpillar tractor for working on waterlogged soils.

On the skidding, trees begin to be felled from the far end, retreating from the boundary of the cutting area to the height of the tree (there is no need to lay a trail here, which also prevents damage to trees outside the cutting area), with the top in the direction opposite to the skidding. The branches of felled trees are cut off and placed near the growing trunks so as not to damage the cambium of the trunks and roots during skidding. Then, from the nearest side of the apiary to the upper warehouse (loading area), the trees are felled with their crowns onto the skid at an angle to it of no more than 40 0 ​​for skidding the logs by the tops. The branches are cut off and the nearest ones are taken out on a trail to protect the soil and trees.

The branches removed from the trail are scattered or piled into small piles up to 0.5 m high. The exception is winter through cuttings in spruce-aspen plantations, where, in order to avoid attracting moose that damage the spruce, skidding should be carried out with the crown. In other cases, along with whip skidding, it is permissible to skid wood with half-lengths or assortments.

Burning logging residues necessarily in coniferous plantations on dry and fresh soils near railways and near other fire-hazardous objects. In other cases, logging residues should be considered as natural fertilizer. On dry and fresh poor soils (types of forest growth conditions A 0, A 1, A 2, B 1), spreading logging residues in the conditions of the Bryansk forest increases the moisture content of the upper soil horizons by 2 times, and the content of nitrogen, potassium, phosphorus in the litter - by 2-4 times. The soil temperature becomes optimal for the roots, which increases the growth of pine by 10-20% (Slyadnev, 1971). To prevent the spread of fire, it is better to localize such areas with mineralized strips. In Kazakhstan (in the field of dry forestry), to accelerate the mineralization of branches and reduce the fire danger, crushing them and scattering them along technological corridors at a distance of 10-20 m turned out to be effective. A self-propelled chipper LO-63B was mentioned for crushing.

It should be noted that agricultural tractors were not designed for work in the forest, and the chassis often has to be repaired. Because of this, arborists are forced to use skidding crawler tractors designed for clear-cutting. But they require wide portages and cause great damage to the forest. The need for serial production of wheeled tractors with an active semi-trailer has long been overdue: TL-28 (6 kN) based on a self-propelled chassis, ALP-1 (9 kN) based on the T-40AM, etc. The MTN-36 log carrier with a semi-trailer has been developed on the basis of the MTZ-80 PL-4 AOOT (Velikoluksky Plant) and semi-trailer loader PPD-6 (VNIILM).

In narrow apiaries, it is used for skidding of canes and assortments. 10-meter skidding manipulator MTT-10 based on MTZ-82 and LHT-55. During cut-to-length harvesting, the removal of logs from the corridor strips is carried out by a log truck equipped with a manipulator for loading and unloading logs up to 4.5 m long. The log truck transports the wood to the logging road.

Log carriers (forwarders) widely used in Scandinavia, where they work in combination with felling, delimbing and cross cutting machines (harvesters). High labor productivity in through fellings (up to 6.0 m 3 / person-hour) in a coniferous plantation 20 m high at a skidding distance of 100 m was demonstrated by the Harvester Lokomo 919/750N felling, delimbing, and cross-cutting machine with removal of stacked material from technological corridor 4 -meter-long timber transporter - Lokomo forwarder with a 10-meter hydraulic manipulator. Within a radius of 5 m, the harvester's electric saw is brought to a trunk with a diameter of 6-50 cm. The length of the cut logs is measured with an accuracy of ± 5 cm using a special roller, and information about the logs is transmitted to the operator's cabin on the display. The branches are cut simultaneously with the measuring and bucking of the trunk and fall in front of the machine, weakening the formation of ruts during further movement of the forwarder. To reduce root damage, the first harvester track is used for the forwarder. Then the first one, going 10 m deeper, moves between the trees, laying logs near the first ones, and, moving forward another 10 m, places them near its future track and the passage of the log truck. So the distance between the passes of the log truck is 25-30 m. Productivity is 90-160 m 3 .

Since 1989, we began to produce domestic “harvesters” and “forwarders” in our country together with the Terratek company from components from Finland, Sweden and other countries. Tests of these machines and other Finnish-Swedish samples have not yet given satisfactory results, since about 20% of the cutting area with wet soil turns into deep (up to 20-80 cm) ruts with the root system of nearby trees cut here, other trunks receive external and internal damage (up to 30% of trees in total). This technique is acceptable in winter or for uniform, gradual and clear cuttings with the preservation of undergrowth.

The Finnish Makeri machine turned out to be acceptable for thinning. This is a basic small-sized tractor, with a caterpillar chain on wheels, equipped in two versions, as a feller-buncher and a feller-delimbing-crossing machine. Power cutting felling knives cut trunks with a diameter of up to 25 cm. Machine width - 1620 mm, length - 2.6 m, height - 2.2 m, weight - 2-4 tons, engine power - 22 kW, traction force - 0.5 kN, productivity - 3.5-4.6 m 3 / h. It damages 5-10% of the number of trees and 10-15% of the soil surface (Nerman et al., 1984; Giltz et al., 1986).

Other new machines can be found in the “Index of current regulatory and technical documentation for standardization in forestry.”

To organize and carry out mechanized thinning, plan the need for equipment, as well as labor and monetary costs, and draw up projects for organizing forestry for individual regions of the country, calculation and technological maps (CTCs) have been developed. The form of the production flow chart is given in the Manual on thinnings.

In the system of machines for integrated mechanization of forestry for 1981-1990. thinning technology is differentiated into a number of basic technological processes: care of young trees, thinning with logging, processing of wood raw materials.

Caring for young trees includes lightening and clearing in forest plantations and natural young trees, aimed at forming plantings according to their species composition. Harvesting marketable timber is of secondary importance.

Technological processes are still based on low-productivity manual means. The performance of motorized backpack hedge trimmers of the Secor type mainly depends on the power and weight of the unit. An analysis of the development process of the Secor hedge trimmers shows that the curves characterizing the dynamics of growth in labor productivity and the expenditure of physical energy of the worker can develop positively as the mass of the unit decreases. Otherwise, labor productivity growth is not expected. In the coming years, along with the improvement of the Secor-3 brush cutter, a lighter (and somewhat less powerful) Secor-2 brush cutter will be created ( symbol). It should be noted that technical idea, embedded in a backpack motorized tool for thinning in young forests, is exhausting itself.

The prospect of comprehensive mechanization of work in young forests is outlined through the use of tractor brush cutters. Such brush cutters have already been created; for example, a brush cutter-clarifier for the care of row crops coniferous species and corridor cutter RKR-1.5 for caring for row oak crops. This mechanism increases labor productivity in thinning in young forests by more than 10 times.

The use of tractor brush cutters requires compliance with a number of conditions. According to E.N. Shakhov, for successful work The brush cutter-clarifier must take into account the following forestry requirements: 1) the width of row spacing in crops must be at least 3.5 m; 2) stumps located between the rows must be lowered in advance to a height of no more than 10 cm above the soil surface, and trees with a diameter of more than 5 cm at a height of 0.4 must be removed; 3) caring for crops by lightening them should be started in a timely manner and carried out regularly, avoiding the development of shading vegetation; 4) the cutting height should be in the range of 400-1000 mm; 5) cut vegetation must be placed on the ground so that it does not overwhelm or damage row crops; 6) there are no special requirements for the quality of cutting.

From this characteristics of the requirements we can conclude that effective work for growing highly productive forest plantations begins with the creation of forest crops in cleared areas in straight rows and with regular maintenance.

The prospects for mechanization of the care of naturally occurring young animals are less clear. On the one hand, this is due to the lack of clear directions in the application chemicals, on the other hand, the lack of forestry data on the effectiveness of technology and its conditions possible application(for example, a tractor brush cutter for laying technological corridors in combination with working in the bushes with power tools or using machines with a hydraulic manipulator equipped with special cutting devices). The figure shows two versions of such a brush cutter - with hydraulic manipulators and a cutting device at the end. In both cases, it is proposed to use a spiral helical cutter and accumulator for chopping standing trees. Calculations of the potential productivity of machines under average conditions of young animals show a certain promise of this technical solution. Thus, at a boom speed of 0.5 to 1.5 m/s, it is possible to chop and feed into a container from 2.7 to 4.4 tons of green wood chips per hour.

Prerequisites for mechanization of thinning with timber harvesting. Between individual directions of technical progress, as between the cells of a single organism, there is a close relationship and certain proportions. These words can be attributed both to the assessment of the “timber industry - forestry” system, and, to a certain extent, to the “agriculture - forestry” system.

Thinning with timber harvesting in technical and technological aspects are a type of logging, and many techniques and machines are used in both clear-cutting and selective cutting (gasoline-powered saws, skidders, logging trucks, etc.). When solving issues of mechanization of thinning, we have the right to use the rich arsenal of forestry science.

In turn, one should not lose sight of the main directions of development of mechanization Agriculture, for example, energy and material handling operations, where increased energy saturation and operating speeds are expected. The power of hydraulic systems will increase. Many years of experience shows that it is possible to create special forestry tractors by maximally unifying them with mass-produced agricultural tractors.

Characteristics of trees cut down during thinning and harvested products. If thinning is carried out with the aim of obtaining forest products, then it should be taken into account that there is a close connection between the choice of work technology and the specified assortments. For example, in order to obtain only green chips, it is enough to fell the tree, deliver it to the crushing plant and split it. If you need to prepare maximum amount assortments, it is necessary to perform felling, limbing, bucking into round assortments, sorting and stacking them, carry out transport operations, splitting branches and tops and sorting green chips. The characteristics of trees cut down in thinning areas determine the qualitative boundaries of the resulting forest products (assortments). The size of trees cut down also greatly influences the productivity of labor and machinery.

The technology and quality of products obtained from thinnings are closely related to such concepts as small trees, logging waste, which in turn has a connection with the direction full use tree biomass.

The term logging waste refers to wood residues generated during tree felling, delimbing trunks, bucking logs and debarking assortments: branches, twigs, tops, thin trees, butts, peaks, bark and tree greens.

The term thin trees usually refers to trees with a diameter at a height of 1.3 m ≤ 14 cm. Only small assortments can be harvested from such trees or used as technological raw materials. At the same time, there is also a restriction on the lower diameter equal to 6 cm. Trees whose diameter at a height of 1.3 m ≤ 6 cm, i.e. brushwood, must be classified as logging waste.

To analyze the technology of work and plan the use of timber harvested from thinning, it is proposed to use the following division of felled trees:

1) brushwood (logging waste) - stems with a diameter of 6 cm at a height of 1.3 m;

2) thin trees - diameter from 6 cm (lower) to 14 cm at a height of 1.3 m;

3) large-sized trees - diameter at a height of 1.3 m is 14 cm or more.

According to O. Liepiņš, in the Latvian SSR, thin-sized trees in through-cuttings in terms of the number of trunks account for 78%, and in thinnings - 97%.

During clarification and cleaning, it is possible to harvest only brushwood. Moreover, in summer time woody greens predominate in the mass. During thinning, thin-sized trees predominate (93-98%) and up to 79% of business assortments can be obtained from thin-sized coniferous trees. At best, woody greens account for 1/5 by weight. Large-sized trees are mainly obtained from pass-through fellings (up to 60%), but we also have to take into account a significant proportion of small-sized trees. There is even less woody greenery here, and its mass does not exceed 14%.

Sharp differences in the size and quality groups of forest raw materials obtained during thinning largely determine the technology of work at the present time and must be taken into account when developing technical means for the future.

Studies of machine removal of trees show that it is important for designers to know such characteristics of the object of labor as mass, height of the center of gravity, diameter at the cutting height. In this case, you need to know their average and maximum values. According to G. Grinfelde (1977), the weight of trees cut down during thinning is on average 24-43 kg, and the height of the center of gravity ranges from 2.9-3.2 m.

Consideration of the characteristics of trees cut down in thinnings suggests that the technology of work and the equipment created should differ significantly from that used in final fellings.

Consumption of new types of timber harvested from thinnings. As already noted, the choice of technology for thinning operations is fundamentally influenced by the factor of demand for timber. The growth in demand for timber and the intensification of forestry are discussed in detail in the works of forest economists.

Let us dwell on two points of a technical and economic nature: 1) the emergence of demand for industrial wood chips and commercial woody greens; 2) development of new technology in connection with this.

The demand for technological chips of reduced quality and for woody greenery leads to the fact that on the same areas it becomes possible to significantly increase the harvesting of commercial forest products.

Research and production experience in the USSR, USA, Finland, Canada, Sweden show that processing whole trees into technological chips increases the yield of marketable wood pulp compared to using only business parts of the trunk: in high-quality plantations by 30-40%, in medium-quality plantations by 100%, in low quality plantings by 200-300%.

The idea of ​​using a whole tree was simultaneously put forward in the USSR and the USA; In the USSR, the production of woody greens is more developed, and in the USA, the production of technological chips from whole trees is more developed. Currently in the USSR there is an increase in the pace of research and experimental work associated with the processing of whole trees, especially small ones, into technological chips. Successes in this area include the development in the USSR (the Splav research and production association) of methods for sorting green chips into technological and fuel chips, separating green wood as a marketable product.

Due to the growing restrictions in application for fuel needs liquid fuel The issue of replacing it with other types of fuel, including wood, is on the agenda.

Over the past ten years in industrial developed countries world, a new concept of “biothermal energy” has appeared and is developing, associated with the use forest resources. With the current level of knowledge and technology, the conversion of wood into energy is possible in the following main ways: combustion, carbonization, gasification, liquefaction, with preference given to direct combustion. Wood burning is considered one of the most pure species energy production.

The first objection to the widespread use of wood as fuel is the fact that energy savings from the use of wood in construction and industry are often greater than those achieved by the use of wood fuel. For example, when replacing wood structures with steel or plastic, their production requires 4-6 times more energy. It is generally accepted that in terms of energy production, 1000 liters of oil are equivalent to air-dried firewood in a volume of 4-6 liters. m 3.

Based on the patterns of development of large-scale energy, it can be stated in advance that forest waste can serve as a raw material for the needs of so-called small-scale energy. The fact is that the logging stock in the intensive forestry zone of the European part of the USSR is highly dispersed and the concentration of fuel chips in areas with a removal distance of 30-50 km does not exceed 20-40 thousand pl. m 3 /year.

Currently, more than 300 designs of devices for burning wood fuel are known in the world. The most promising near-term prospect is the use of wood chips and solid wood in the latest designs of fireboxes and stoves currently being developed, the thermal efficiency of which exceeds 80%.

As an example of top up options energy balance of the national economy through the use of forest biomass, data is provided on the availability of biomass in the logging fund of state forests of the Latvian SSR.

The wood of branches and tops makes up approximately 17% of the total mass cut down, which is equivalent to 10-12% of the republic's thermal energy consumption. In this case, a significant share can come from timber obtained from thinning. The costs of its harvesting and transportation should be excluded from the gross energy of forest biomass.

One of optimal solutions The problem facing us is the expansion of development work on the creation of progressive means of mechanization of collection, transportation and processing of fine wood and logging waste and technology for their storage.

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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 the types of equipment used.

Metal cutting is a metalworking operation involving the action of a cutting or percussion instrument onto 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. Cutting tool For chopping metal, a cross-cutting tool or chisel is used, and a hammer is used for impact. 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 shape is used cutting edge(“ditcher”).

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

1. Curvilinearity of the cut edge (weak fastening of the part in the vice).
2. The edge is “torn” (the blows were carried out with a dull chisel or an incorrectly sharpened crosspiece).
3. The parallelism of the sides of the product is broken (misalignment of the marks or the workpiece in a vice).
4. The depth of the grooves varies along the length (the angle of the crossbar was not adjusted; the impact was uneven).
5. The appearance of nicks on the part (dull chisel).
6. 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.

Hand cutting of 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 is equipped with 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. cuts sheet metal small thickness (up to 0.5 mm) and is activated 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.

Equipped with 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.). Allowable thickness 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 corner notching 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. The compact design includes a measuring scale and chisels for chopping. 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 chisel cutting techniques are 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 at the right moment (single stroke when the handle is pressed). 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 cutting materials cope with different workpieces. It is only important to choose the right equipment.