How to cut leaf metal with lever scissors. Cutting with a hacksaw

Manual cutting of metal

In locksmith and tin workshops, it is widespread Metal cutting with hand scissors (rice. eleven.49). With the help of scissors, it is possible to cut a very firebox and strip material, as well as blanks of complex configuration.

Cutting leaf and strip metal with scissors is carried out without removing chips. with a preparation. The essence of the process Cutting cutting consists in the separation of part of the metal under the pressure of a pair of cutting knives along the line of their direction.

In the process of work, a cut sheet 2 (rice. eleven.49, a) It is placed between the knives one and 3. The upper knife, dropping, presses on the metal, pressing it to the lower knife. Both knives, pressing, crush the surface of the metal, and then share it with the resulting cracking cracks. The angle of pointing (3 cutting part of the scissors ranges from 65 to 80 °, depending on the hardness of the cut metal; for soft metals (copper and other.) it is 65 °, for metals of medium hardness. 70. 75 °, for solid metals. 80 °. To reduce friction of the knives in the process of working on their cutting surfaces, the rear angle A, equal 2, is created. 3 °.

To get a clean cut, you must choose the right gap t between the upper and lower knives (rice. eleven.49, b). With a small gap, the direction of carcassing cracks does not coincide with the direction of the cut and its surface will be rough, “torn”. With a large gap, the cut surface will have large burrs.

The size of the gap between the knives depends on the thickness of the cut metal, but there should not be more than 0.5 mm. In manual scissors, this gap usually does not exceed 0.1. 0.2 mm.

In order to reduce the power consumed when cutting, cutting knives are installed at an angle f of one to another (rice. eleven.49, a). The larger this angle, the less the cutting force. However, the large angle of inclination of the knife increases its course and creates an effort, pushing a sheet from under the knives. Guided by these considerations, the angle F is accepted equal to 7. 12 °.

Depending on the device of cutting knives (blades), manual scissors are divided into The scissors are straight (rice. eleven.fifty, a). with straight cutting blades, intended mainly for cutting the material in a straight line and around the circle of a large radius; scissors

crooked. with curved cutting blades (rice. eleven.fifty, b, in) and finger scissors. with thin and narrow cutting blades (rice. eleven.fifty, G), used for cutting in the sheet material of holes and surfaces with small radii.

By the location of the cutting knives, manual scissors are divided into right and left. U right scissors The bevel of the cutting part of the lower knife is on the right side, and at left. From the left side.

Hand scissors according to GOST 7210-59 are made of steel stamps 45, 65 and 70. The blades of the scissors are hardened with subsequent vacation to the hardness of HRC 52. 58. The cutting edges of the scissors should be straightforward, without cracks and rubble. The length of the cutting knives to the rotation axis is usually from 55 to 130 mm, the total length of the scissors is from 200 to 400 mm. The most common scissors are 250. 320 mm.

When performing a manually cut, scissors are held with the right hand. The thumb is placed on the upper handle of scissors (rice. eleven.51, o), and the index, middle and ring fingers capture the bottom-

During the cutting process, the blades of the scissors should not be opened to a large angle, since with a large opening the blades will be expelled, rather than cut the metal. The blades of the scissors need to be opened by about 2/3 of their length.

To prevent the serifs and burrs, when moving the blades of the scissors forward, at a marginal risk, it is necessary that the planes of the blades are pressed to the plane of the cut and go according to the marking. The cutting edges of the blades should be well sharpened, and the cutting surfaces (planes) should be correctly adjusted and fixed to the axis. Checking scissors are usually cutting paper: well.sharpened and adjusted scissors should cut paper. Cut the marked sheet so that the marking risk is in sight. Therefore, cutting sheet metal in a straight line and along a curve (circle and rounding) without sharp turns is carried out with right scissors (rice. eleven.52, A, b, d).

Cut the sheet along the curved contour or cut round discs most convenient with scissors with curved cutting blades. When cutting holes and internal contours of a curved outline, it is necessary to cut a hole in the material in the material for the passage of the blades of the scissors, and then cut out at risk (rice. eleven.52, In, d). To cut holes, it is better to use finger scissors.

The quality of the cut depends on how correctly the workpiece is relative to the cutting edges of the scissors. There should be a right angle between the cutting plane and the workpiece, otherwise the scissors will spring and jam the workpiece, a dent will appear on the workpiece and it will be much more difficult to cut it. With manual scissors you can cut leaf and strip steel up to 0.8 mm thick, roofing iron up to 1 mm thick, sheets of copper and brass up to 2 mm thick.

Manual cutting Metal is also performed On lever scissors: stools, flyers, with a gear rake and other types.

Lecture marking and cutting metal methodological development

Markings are the operation of applying lines and points for the workpiece designed for processing. Lines and points indicate the boundaries of processing.

There are two types of markings: flat and spatial. The marking is called flat when the lines and points are applied to the plane, the spatial. when the marking lines and points are applied to the geometric body of any configuration.

Spatial marking can be made on a marginal plate using a marking box, prism and squares. During spatial markup, prisms are used to rotate the marked workpiece.

For flat and spatial markings, a drawing of parts and blanks for it, a marking slab, a marginal tool and universal marginal devices, measuring tools and auxiliary materials are required.

The solid instrument includes: a devil (with one tip, with a ring, double.sided with a curved end), a marker (several types), marker, kerers (ordinary, automatic for a stencil, for a circle), Crointy with a conical mandrel, a hammer, a central zircult. rectangle, marker with prism.

Devices for marking include: marking stove, marginal box, marginal squares and bars, stand, a flight with a damn, a flight with a movable scale, a centroting device, a dividing head and a universal markup, a rotary magnetic slab, dodgers, adjustable wedges, prisms, prisms. screw support.

Measuring instruments for marking are: a line with divisions, a caliper, a flight with a movable scale, a standard, a square, an angular, a crumb, level, a control line for surfaces, a probe and reference tiles.

The auxiliary materials for marking include: chalk, white paint (a mixture of chalk diluted in water with linseed oil and the addition of a composition that prevents the drying of oil), red paint (a mixture of shellac with alcohol with the addition of dye), lubricant, detergents and grassy materials, wooden bars and slats, small tin dishes for paints and brush.

Simple marking and measuring instruments used in locksmith work are: hammer, devil, marker, ordinary core, square, circulator, marking stove, line of divisions, caliper and Crontzirkul.

Flat or spatial markings of the parts are carried out on the basis of the drawing.

Prior to markup, the workpiece should undergo mandatory preparation, which includes the following operations: cleaning the parts from dirt and corrosion (not to be made on the marking plate); degreasing the part (not to be carried out on the marking plate); examination of the part in order to detect defects (cracks, shells, curvatures); check of overall sizes, as well as processing allowances; determination of the marking base; covering with white paint of surfaces subject to marking and applying lines and points on them; Determination of the axis of symmetry.

If a hole is accepted for the marking base, then a wooden cork should be inserted into it.

The marking base is a specific point, the axis of symmetry or a plane, from which, as a rule, all sizes on the details are measured.

Napting is the operation of small points-strangers on the surface of the part. They determine the axial lines and centers of the holes necessary for processing, certain straight or curved lines on the product. Napting is made in order to designate the parts of persistent and noticeable signs that determine the base, boundaries of processing or place of drilling. The surgery operation is performed using Chertille, Kerner and Hammer.

Marking using the template is used in the manufacture of a significant number of identical parts. A template made of tin with a thickness of 0.5–2 mm (sometimes stiffness is attached with a corner or wooden rail), is superimposed on the flat surface of the part and covered with a damn about the contour. The accuracy of the applied circuit on the part depends on the degree of accuracy of the template, symmetry of the digging of the Chertilka, as well as on the method of advancing the Eastern Cheritan (the tip should move perpendicular to the surface of the part). The template is a mirror display of the configuration of parts, lines and points that should be applied to the surface of the part.

The accuracy of the marking (the accuracy of transferring the size from the drawing to the part) depends on the degree of accuracy of the marking plate, auxiliary devices (squares and marginal boxes), measurement tools, tools used to transfer the size, on the degree of accuracy of the marking method, as well as on the qualification of the markings. Marking accuracy is usually from 0.5 to 0.08 mm; When using reference tiles. from 0.05 to 0.02 mm.

When marking, you should carefully handle pointed devils. To protect the employee’s hands before the marking on the tip of the damn it is necessary to put on a cork, a wooden or plastic cover.

To install heavy parts on the marking plate, thala, telfs or taps should be used.

Oil or other fluid spilled on the floor or marginal plate can cause an accident.

Tools, devices and materials used in marking

Deckliki are the simplest tool for applying the contour of the part to the surface of the workpiece and are a rod with a pointed end of the working part. Deckliks made of instrumental carbon steels U10A and U12A in two versions are made: one.sided and bilateral. Chertilles are made 10 length. 120 mm. The working part of the Chertilka is hardened at 20. 30 mm to hardness HRC 58. 60 and sharpened at an angle 15. 20 °. The risks to the surface of the part are applied with a damn thing using a large.scale ruler, template or sample.

Reimmas is used to apply for the vertical plane of the workpiece. It is a devil fixed on a vertical rack installed on a massive base. If it is necessary to apply scushes with higher accuracy, a tool with a scale is used. a caliper.

To install the flight on a given size, you can use blocks of end measures of length, and if very high marking accuracy is required, then use a vertical large.scale ruler.

Sensor circules are used to apply arcs and dividing segments and angles into equal parts. Sensor circules are made in two versions: simple, allowing to fix the position of the legs after they are installed on size, and the spring, used for a more accurate installation of size. To mark the contours of the responsible parts, the marginal caliper is used.

Metal cutting with hand scissors

In locksmith and tin work, cutting metal with hand scissors is often used often. With the help of scissors, it is possible to cut a very thin sheet and strip material, as well as blanks of complex configuration.

Cutting leaf and strip metal with scissors is carried out without removing chips. with a preparation. The essence of the cutting process is to separate part of the metal under the pressure of a pair of cutting knives along the line of their direction.

In the process, the cut sheet 2 (rice. 67,

A) It is placed between knives 1 and 3. The upper knife, dropping, presses on the metal, pressing it to the lower knife. Both knives, pressing, are crushing the surface of the metal, and then share it with the resulting cracks in the coat. The angle of pointing (3 in the cutting part of the scissors ranges from 65 to 80 ° depending on the hardness of the cut metal: for soft metals (copper and others.) It is 65 ° for metals of medium hardness 70–75 °, for solid metals 80 ° to reduce friction of knives during operation on their cutting surfaces created the rear angle A equal to 2-3 °.

To obtain a clean cut, it is necessary to choose the right gap T between the upper and lower knives (rice. 67, b).

With a small gap, the direction of carcassing cracks does not coincide with the direction of the cut, and its surface will be rough, “torn”. With a large gap, the cut surface will have large burrs. The size of the gap between the knives depends on the thickness of the cut metal, but there should not be more than 0.5 mm. In manual scissors, this gap usually does not exceed 0.1-0.2 mm.

In order to reduce the power consumed when cutting, cutting knives are installed at an angle f of one to another (rice. 67, a). The larger this angle, the less the cutting force. However, the large angle of inclination of the knife increases its course and creates an effort, pushing a sheet from under the knives. For these considerations, the angle F is taken equal to 7-12 °

Depending on the device of cutting knives (blades), manual scissors are divided into straight scissors (rice. 68, o)- with direct cutting blades, TTRred mainly for cutting the material in a straight line and around the circumference of a large radius, scissors crooked

With thin and narrow cutting blades (rice. 68, g) used for cutting holes and surfaces with small radii in the sheet material.

By the location of the cutting knives, manual scissors are divided into right and left. In the right scissors, the bevel of the cutting of the lower knife is on the right side, and in the left on the left side.

Hand scissors are made of instrumental carbon steel of the brand U7. The blades of the scissors are hardened with subsequent vacation until the hardness of Naes 52-60. The cutting edges of the scissors should be straightforward, without cracks and rubble.

The length of the cutting knives to the rotation axis is usually from 55 to 110 mm, the total length of the scissors.

200 to 400 mm. The most consumed scissors are 250-320 mm long.

Metal cutting techniques with hand scissors.

When performing a manually cut, scissors are held with the right hand. The thumb is placed on the upper handle of scissors (rice. 69, a), and with the index, middle and ring fingers capture the lower handle. The little finger should be between the handles: during cutting they are pushed by scissors. Some locksmiths prefer to do this with an index finger (rice. 69, b), but this technique is not quite convenient. The leaf is served with the left hand, slightly lifting it to facilitate the advancement of the scissors.

During the cutting process, the blades of the scissors should not be opened to a large angle, since with a large opening the blades will be expelled, rather than cut the metal. The blades of the scissors need to be disclosed by about 2/b of their lengths.

To prevent seals and burrs, when moving the blades of the scissors forward but a marginal risk, it is necessary that the planes of the blades are pressed to the plane of the cut and go according to the marking. The cutting edges of the blades should be well sharpened, and the cutting surfaces (planes) should be correctly regulated and fixed to the axis. Checking scissors are usually cutting paper: well.sharpened and adjusted scissors should cut paper. Cut the marked sheet so that the marking risk is in sight. Therefore, cutting sheet metal in a straight line

Lines and along the curve (circle and rounding) without sharp turns are made with right scissors

Cut the sheet along the curved contour or cut round discs more conveniently with scissors with curved cutting blades. When cutting holes and internal contours of a curved outline, it is necessary to cut a hole in the material in the material for the passage of the blades of the scissors, and then cut out at risk (rice. 70, c). To cut holes, it is better to use finger scissors.

The quality of the cut depends on how correctly the workpiece is relative to the cutting edges of the scissors. There should be a right angle between the cutting plane and the workpiece, otherwise the scissors will spring and jam the workpiece. A dent will appear on the workpiece and it will be much harder to cut it.

With manual scissors you can cut leaf and strip steel up to 0.8 mm thick, roofing iron up to 1 mm thick, sheets of copper and brass up to 2 mm thick.

Metal cutting with lever scissors. Manual cutting of the metal is also performed on lever scissors: stools, flywheel, with a gear rake and other types.

Stool scissors, unlike manual, are made large sizes. They have one bent handle with a pointed end for attaching to a thick board or to a workbench (rice. 71, a), and the second, elongated. to work with the hand. Wistal scissors are stable in work and give considerable freedom to the shirts of a locksmith. They cut sheets with a thickness of 2-3 mm.

Cutting the metal with scissors

Cutting with hand scissors. Scissors are used for both manual and machine cutting of metals. According to GOST 7210, three types of hand scissors are made:

Scissors of all types are made in left.handed design (the lower blade is located on the left), and by order of consumers and in the right.winging design (the lower blade is located on the right). In Fig. 6.33 shows the appearance, and in the table. 6.1 shows the main sizes of scissors.

Таблица 6.1. Размеры ручных ножниц по ГОСТ 7210

The connection of the levers of the scissors in the hinge should not have distortions. Should ensure a tight fit of the contacting surfaces, while the scissors should open and close smoothly, without jamming, with the effort attached in the coverage zone, no more than 2 N for scissors 200 and 250 mm and 3 N for scissors 320 and 400 mm long and 400 mm long and 400 mm.

As the scissors close the cutting, the cutting edges in the cutting area when moving along the entire length of the cutting part should be provided, for which

Rice. 6.33. Hand scissors

The internal surfaces of the blades have curved relative to the plane of cutting: the left blade. to the right, and the right blade. to the left.

In the scissors closed to the stop, the blades should be mutually overlap, and the ceiling at the ends of the blades should be:

In locksmithing, scissors that have a length of 250-300 mm are most often used.

The angle of pointing in scissors ranges from 65 to 85 °, depending on the hardness of the cut metal. For soft metals (copper and t. P.) it is 65 °, for metals of medium hardness 70–75 °, for solid metals 80–85 °. To reduce friction of scissors knives, when working on the blades, the rear angle is created os = 1.5-3.0 ° (rice. 6.34). Scissors knives are made of carbon steel U7 and U7A according to GOST 1435 or from steel of 8XF brand according to GOST 5950, the axis is made of steel of brand 35 according to GOST 1050, the cutting part of the scissors is hardened.

Rice. 6.34. Cutting angles of scissors knives: one. upper knife; 2. Lower knife

Both right and left scissors are used in locksmithing, rice. 6.35. When cutting the sheet with right scissors, risk on the cut metal is all the time. When working with the left scissors, to see the risk, you have to bend the cut metal with your left hand, shifting it through the right hand, which is very inconvenient. Therefore, cutting sheet metal in a straight line

Rice. 6.35. Right (upper) and left (lower) hand scissors and use of right scissors

lines and along the curve (circle and rounding) without sharp turns are made with right scissors.

The edges of the scissors in the hinge connection should fit tightly to each other and have an easy move. In tight course, there is a lot of friction, causing unnecessary efforts in work and rapid wear of the cutting edges. With a large gap between the cutting edges, the cut material will be crumbling and jammed.

With manual scissors you can cut leaf steel with a thickness of up to 0.7 mm, roofing iron. up to 1 mm thick, copper sheets. up to 1.5 mm thick.

When cutting the metal, the scissors are not completely opened, but only so that they can capture the sheet by a size of not more than 30 mm at a direct risk. You should not make the full opening of the cutting edges, since they do not cut, but pushed the sheet.

The scissors are held in the right hand, covering the handles with four fingers and pressing them to the palm. The little finger is placed between the handles of the scissors, rice. 6.36a. The compressed index, ring and middle fingers are unclenched, the little finger is straightened and the lower handle of the scissors to the desired angle is removed by its effort. With his left hand holding the sheet (rice. 6.36b), Serve it between cutting edges. Directing the upper blade exactly in the middle of the marking line, which should be visible during cutting. Then squeezing the handle with all the fingers of the right hand (except the little finger), cut.

Rice. 6.36. The position of the fingers on the handles when cutting with scissors (a), Taking cutting scissors on

When cutting with scissors external curved contours, the leaf is rotated so that the scissors do not close the fishing line for the cutting trimmer. In Fig. 6.37a The direction of cutting is shown by the right, and in the rice. 6.37b. left scissors. The fingers of the left hand supporting the sheet from below must have such a position so that they do not fall into the cutting zone.

Cutting internal curved circuits is performed with scissors with curved narrow cutting edges, rice. 6.38p.

Finds the use and cutting of metal with hand scissors with the clamping of one handle in a vice, rice. 6.386. This technique is used with rectilinear cutting of metal of large thickness.

Rice. 6.37. Reception and direction of cutting along the curved external risks with the right (a) and left (b) scissors

Rice. 6.38. Cutting a round hole (a) and cutting with clamping scissors in a vice (b)

The quality of cutting is determined by checking the cut line by risks, the absence of incisions, dents and burrs.

Metal cutting with manual lever scissors. Hand lever scissors are used for cutting sheet steel up to 4 mm thick, aluminum and brass. up to 6 mm. Before work, check the quality of lubrication of the rubbing parts, smoothness of the lever, the absence of a gap between the cutting edges and a tight fit to each other. A tight stroke of knives requires great effort in work and causes premature wear of the cutting edges. A large gap between the cutting edges worsens the quality of the cut, the sheet is drying, the knives dull and break.

When cutting metal with hand.made lever scissors (rice. 6.39) with the right hand they cover the handle of the lever and take it to the upper position (the upper knife rises). Then the sheet is laid on the cutting edge so that the left hand holds it in a horizontal position, and the fishing line for the cutting trimmer is in sight and coincided with the blade of the upper knife. The lever with a knife is lowered down until part of the metal is cut, then the lever is lifted. With his left hand, they raise a sheet, move it at risk along the cutting edge of the upper knife and repeat the method of cutting.

Cutting metals. Methods, metal cutting tool

The metal is cut with manual or mechanical hacksaws, as well as manual and mechanical, lever, parallel and disk (round) saws.

Large varietal metal (round, strip, corner, double.P.) cut on drive hacksaws and disk saws, as well as electric and gas, sheet metal. manual and drive scissors, pipes. manually with a hacksaw and pipeline (mechanical cutting are carried out on special machines).

For cutting hardened steel and solid alloys, thin disk grinding circles are used, as well as the anode-mechanical and electro.isk methods of cutting metals.

Manual hacksaw device. A manual hacksaw consists of a machine (frame), in which a hacksaw is fixed.

Carebout canvases are made of instrumental steel grades of 9XS, U10, U10A, U12, U12A or soft carbon steel (U8a, U9, U9 and U9A) with subsequent teeth cementation. The hacksaw canvas is thermally processed so that the lower working part of the canvas with teeth is thermally processed with greater hardness than the upper. This heat treatment reduces the breakdown of the hacksaw cloth during operation. Carebout canvases are made with a small and large tooth. The number of teeth per 25 mm of the length of the hacksaw cloth ranges from 15 to 32. The teeth of the canvas are diluted in different directions to reduce the friction of the canvas on the side surfaces of the processed workpiece and exclude the jamming of the canvas in the propyle. The size of the teeth divorce should be such that the width of the cut is more than the thickness of the hacksaw canvas by 0.25-0.5 mm.

Dear bending each two adjacent teeth in opposite directions by 0.25–0.6 mm. Use the divorce of small teeth by creating a wave along the lower part of the canvas. The amplitude and step of the wave depend on the thickness of the canvas and the size of the teeth.

For cutting soft and viscous metals (copper, brass), hacksaw canvases with teeth pitch are used. 1 mm, solid metals (steel, cast iron). 1.6 mm, soft steel. 2 mm. For locksmith work, hacksaw cloths are usually used, in which 15 teeth are placed on a length of 25 mm.

The cutting of the slots in the heads of small screws under the screwdriver is carried out with a thin canvas (thickness 0.8 mm). In the heads of larger screws, slots are cut out with an ordinary hacksaw. Wide slots in large screws are cut with canvases with a thickness of 1.5-3 mm or a hacksaw is inserted at the same time two or three canvases of normal thickness.

The process of cutting with a hacksaw. Before starting work, you need to choose a hacksaw canvas, in accordance with hardness, shape and size of the cut material. It is also necessary to check whether the canvas is correctly inserted into the frame: the teeth should be directed by the acows from the handle, the tension of the canvas should be strong enough, but not excessive, as this can cause a breakdown of the canvas.

The position of the body and hands of the locksmith during work should be as shown in the rice. 2, a. Another way to capture the frame is shown in the rice. 2, b (difference. in the position of the fingers).

During cutting, the hacksaw is kept mainly in a horizontal position. The movements should be smooth, without jerks and with such a scale that almost the entire canvas works, and not just its middle (normal scope of at least 2/3 of the length of the hacksaw).

The pressure force on the hacksaw depends on the hardness of the processed metal and its size. On average, the force must correspond to 1 kg per 0.1 mm of the thickness of the canvas.

It is necessary to press the machine with both hands, while exerting the greatest pressure with the left hand, and the movement of the machine should be carried out mainly by the right hand attached to its handle. When idle, they do not press the hacksaw. When working with a hacksaw machine, you need to do no more than 40-50 moves per minute. At a faster pace, the canvas heats up and blows faster.

If at the beginning of cutting the hacksaw glides over the surface, then the cutting place is tied with a chisel or cut by the edge of the file.

When cutting parts with sharp ribs, it is necessary to ensure a smooth entry of teeth into the metal and prevent the machine’s bouncing when moving from tooth to toe. Otherwise the teeth are broken out of the canvas and the cutting process is impossible.

Manual hacksaw most often work without cooling. To reduce friction of the canvas against the wall of the sawn groove, it is useful to lubricate it with machine oil, thick grease of fat or graphite ointment, which includes 2 parts of fat and 1 part of the graphite. With mechanical cutting, the drive hacksaw must be cooled with liquid. soap water or emulsion.

Weak tension of the canvas sometimes contributes to the “departure” of it to the side. When weapons, the canvas should start cutting in a new place. from the back. An attempt to straighten a slanting slot leads to a breakdown of the canvas.

For longer use of the habilling canvas, it is recommended to first cut soft materials for them, and then, after a certain gear spacing, more solid.

With a breakdown of at least one tooth, the work should be stopped with a hacksaw, otherwise adjacent teeth and the rapid blunt of all the others will occur. To restore the cutting ability of the hacksaw, in which the tooth has crushed, it is necessary on a sharpener or a grinding circle to hide the two teeth adjacent to it along the line a. a

If during the cutting the old, worked out hacksaw canvas broke, then you can not continue to work with a new hacksaw, since the width drain it for a new canvas will be small and it will not enter the slot. In this case, the product is rotated and the cutting begins in another place.

Cutting with a hand hacksaw

Rules of cutting.The cut workpiece is reliably clamped in a vice, because if when cutting it shifts, the canvas may break.

The habill is attached in the frame so that the tooth cuts when moving forward, and is well pulled. With faint tension, the habits will deviate to the sides, which will cause a breakdown of the canvas. In case of severe tension, the breakdown can cause the slightest skew of the hacksaw.

The techniques of holding the hacksaw with the right and left hand and the worker stand during cutting are shown in rice. 2. During the move forward. the working move. they are pressed on the hacksaw with both hands, while most of the effort of the left hand is spent on the pressure, and the right hand on the progressive movement of the hacksaw. The reverse move of the hacksaw is idle, without pressure.

To facilitate the cut of the hacksaw, you can tilt the workpiece to the backbone. When the canvas crashes, the hacksaw is moved horizontally and over the entire length of the canvas. This provides him with greater durability. It is necessary to work with a hacksaw smoothly and evenly at a speed of 40 double moves per minute when cutting solid materials and 60 moves. when cutting soft.

The pressure force depends on the processed material: it is larger for solid and less for soft materials, as well as when cutting thin metals. strips, pipes. If you make a lot of effort when cutting soft materials, the canvas crashes deep and the teeth will be crushed. When cutting thin metals, a small number of teeth is involved in the work. Great pressure is tended to teeth. Strong pressure will lead to a breakdown of teeth. Before the cutting, in all cases, the pressure on the hacksaw is reduced, the cut off the cut is maintained with the left hand.

It is recommended to first cut soft materials with a new hacksaw laid, and after some gap. solid.

Manual cutting of metals is usually carried out without cooling. To reduce friction, the hacksaw canvas can be lubricated with mineral oil.

If the canvas took to the side and it cuts not at risk, you should not try to straighten its position by turning the hacksaw. you can break the canvas. You need to turn the workpiece and start cutting in a new place. If the teeth have crushed the canvas, it is replaced. Since the worn canvas gives a smaller width of the cut, they begin to cut a new cloth in a new place.

Very thin material is clamped between two wooden bars of 15 thickness. 30 mm and cut with them a canvas with a small step, pressing slightly, with slow movements, using the entire width of the canvas.

Slots in screws are cut out with hand hacksaws (rice. 55, in) With a narrow canvas. Wide slots are made by two canvases folded in thickness.

Cutting materials.The strip material is cut on a narrow plane if its thickness provides simultaneous operation of at least three teeth. Когда это условие не выдерживается, то при врезании давление на зубья будет неравномерным, они могут сломаться. Therefore, thin strip material is cut along a wide edge.

Round, square, hexagonal rods are cut at a horizontal position of the hacksaw, but so that the canvas does not meet when the sharp corners are moving. If the ends of the cut.off workpiece are processed, then it is allowed to cut it from two or four sides and break it off.

Products with wide surfaces are cut, tilting the hacksaw sequentially to the rear and front rib. At the same time, cutting is not on the entire width at once and the work is facilitated.

To cut off the strip from the sheet, the hacksaw canvas is rotated by 90 ° and cut at the horizontal position of the hacksaw (rice. 3, a).

To process the shaped holes in sheet metal, a small hole is first drilled, a canvas is made in it, a hacksaw is assembled and metal is cut out. Shaped parts or slots are performed with a canvas, worn to width 8. 10 mm (rice. 3, b).

Slots in screws are cut out with hand hacksaws (rice. 3, c) with a narrow canvas. Wide slots are made by two canvases folded in thickness.

The main type of marriage when cutting a hacksaw is a scythe section as a result of leaving the canvas. With improper markup, cutting is not at risk, the size of the part is not withstanding. Возможно также повреждение наружных поверхностей деталей при зажиме их в тисках без нагубников.

Cutting metal scissors is characterized by high performance, allows you to cut parts of any shape without removing chips, but requires significant efforts to cut. Therefore, scissors usually cut leaf material. There are also mechanical scissors for cutting rod and profile material.

Thin sheet material is cut with hand scissors: steel 0.5 thickness. 0.7 mm, roofing iron, non.ferrous metals up to 1.5 mm thick. They have short blades and long handles and are made with a length of 200, 250, 320, 360 and 400 mm from steel stamps 65, 70. The cutting part of the scissors is hardened to HRC 52. 58.

Distinguish between scissors rights (rice. 4, a) and left (rice. 4, b). The right scissors are mainly used, in which, during cutting, the bevel of the lower blade is located on the right. Left scissors cut out curved parts. Scissors with curved blades (rice. 4, c) are used to obtain shaped holes in sheets and pipes.

In the section, the cutting part of the scissors has the shape of a wedge with an angle of pointing (β = 70 °. A relatively large angle of pointing is taken so that when cutting the blade is not painted. To reduce friction, the rear angle α = 1 is given. 2 ° (cm. rice. four). The blades of the scissors should be straightforward, acutely and converge along the entire length with a small gap (no more than 0.2 mm). In the absence of a gap, the blades are quickly blunt, with large gaps they do not cut, but they crush the metal.

Cutting with hand scissors

Thin sheet material is cut with hand scissors: steel 0.5 thickness. 0.7 mm, roofing iron, non.ferrous metals up to 1.5 mm thick. Scissors have two short blades (knife) and two long handles. Both parts of the scissors are connected by a hinge. The length of the scissors ranges from 200 to 400 mm.

Cutting leaf and strip metal with scissors is carried out without removing chips by plastic deformation. The essence of this process is the separation of part of the metal under the pressure of a pair of cutting knives along the line of their direction (rice. 7.7). Both knives, pressing, are crushing the surface of the metal, and then share it. To obtain a clean cut, it is necessary to choose the right gap between the upper and lower knives. With a small gap, the cut surface will be rough, “torn”. With a large gap, the cut surface will have large burrs. The size of the gap between the knives depends on the thickness of the cut metal. In manual scissors, this gap usually does not exceed 0.1. 0.8 mm.

In the section, the cutting part of the scissors has the shape of a wedge with an angle of pointing (3 = 70 ° (rice. 7.eight). A large angle of pointing is taken so that when cutting the blades are not painted. To reduce friction, the rear angle A is taken equal to 1. twenty.

Рис. 7.8. Ручные ножницы:

а — правые; б — левые; в — с криволинейным режущим лезвием

Из равенства а 13 у = 90° следует, что величина переднего угла у колеблется от 18 до 19°. Лезвия ножниц должны быть прямолинейными, острозаточенными.

Ручные ножницы изготавливают с прямыми (рис. 7.8, а, б) и криволинейными (рис. 7.8, в) режущими лезвиями.

По расположению режущей кромки лезвия ручные ножницы бывают правые и левые. Правыми называют ножницы, у которых во время резки скос на нижнем лезвии находится с правой стороны, левыми — ножницы, у которых скос находится слева. Правыми ножницами режут по левой кромке изделия в направлении движения часовой стрелки (рис. 7.9, а), а левыми ножницами — по правой кромке изделия против хода часовой стрелки (рис. 7.9, б). В основном применяют правые ножницы, так как при резке все время видна разметочная риска.

При резке ножницы держат в правой руке (рис. 7.10). Большой палец располагают на верхней рукоятке, тремя пальцами обхватывают нижнюю рукоятку, а указательный палец или мизинец помещают между рукоятками (для раздвигания их).

Рис. 7.9. Приемы резки ножницами: а — правыми; б — левыми

Рис. 7.10. Приемы держания ножниц

Наименьшее усилие при резке будет тогда, когда материал глубже вдвигается в зев лезвия ножниц. Однако при большом раскрытии лезвий горизонтальная составляющая усилия резания (рис. 7.11) увеличивается настолько, что ножницы не режут, а выталкивают металл. При величине угла раскрытия примерно 30° силы трения и усилие левой руки рабочего способны противодействовать выталкивающему усилию. Этот угол следует считать наиболее благоприятным для резки металлов ручными ножницами. Ножницы устанавливают перпендикулярно к разрезаемой поверхности (иначе они будут мять металл) и перемещают по разметочной линии, плотно прижимая к прорези. Чтобы отрезаемая полоса металла не мешала, ее отгибают. Ножницами режут только пластичные металлы и сплавы. Листовой металл толщиной до 2 мм можно разрезать ручными ножницами, как показано на рис. 7.12. Ножницы нижней ручкой закрепляют в слесарные тиски, левой рукой подают заготовку в разъем лезвий, а правой рукой создают усилие резания и разжим ножниц. Не разрешается наносить удары молотком по верхней ручке, так как это может вызвать поломку ножниц.

Рис. 7.11. Схема усилий при резке ножницами

Рис. 7.12. Резка ножницами в слесарных тисках

Для резки листовой стали толщиной до 2,5 мм применяют силовые ножницы (рис. 7.13). При работе рукоятку 8 (с насечкой) закрепляют в тисках, а рукоятку 1 (рабочую с пластмассовым наконечником) захватывают правой рукой. Рабочая рукоятка 1 представляет собой систему двух последовательно соединенных рычагов. Первый рычаг 3 заканчивается ножом 5 и соединен витом 6 через шайбу 4 с рукояткой 8. Эта система рычагов увеличивает силу резания примерно в два раза по сравнению с обычными ножницами таких же габаритов. Ножи ножниц сменные и прикреплены к рычагам потайными заклепками. Эти ножницы имеют специальное приспособление для резки прутков диаметром до 8 мм.

Рис. 7.13. Силовые ножницы:

1,8 — рукоятки; 2,7 — рычаги с пружиной ; 3 — рычаг; 4 — шайба; 5 — режущий нож; 6 — винт

Для разрезания металла толщиной до 2 мм применяют стуловые ножницы. Нижнюю ручку закрепляют в параллельных тисках (рис. 7.14) или крепят на столе либо на другом жестком основании. Эти ножницы малопроизводительны, при работе требуют значительных усилий, поэтому их применяют для разрезания небольшой партии деталей.

Рис. 7.14. Резка стуловыми ножницами

Рис. 7.15. Рычажные ножницы:

Для разрезания листового металла толщиной до 4 мм применяют рычажные ножницы (рис. 7.15). Нижний нож 1, заточенный под углом 90°, закреплен на основании ножниц неподвижно. Верхний нож 3 с криволинейным лезвием перемещается рычагом 2. Разрезаемый металл 4 укладывают на нижний нож так, чтобы разметочная леска для триммера располагалась под верхним ножом. Движением рычага вниз лист надрезают. Затем рычаг отводят, заготовка подается дальше по разметке, и процесс многократно повторяют до полного разрезания.

Резка тонколистового металла ножницами. Резка скалыванием.

Резка скалыванием осуществляется на ручных и стуловых ножницах (рис. 1, а и б), на рычажных. вибрационных, гильотинных, дисковых ножницах, пресс-ножницах, на специальных отрезных штампах.

Посмотрев на обрезанную часть листа, мы видим три полосы: две из них, которые по краям, будут узкими и блестящими, это следы врезания ножей (а и в), а поверхность посередине будет матовая (б) от скалывания По линии реза можно наблюдать маленькие трещины и заусенцы. Кроме того, полоса металла толщиной от 2 – 3 мм, от сдавливания ножами по всей линии реза, будет иметь наклеп.

В зависимости от изготавливаемой конструкции, наклеп и трещины необходимо сострогать.

Резка скалыванием происходит следующим образом: разрезаемый материал 2 помещается между двумя ножами 1 и 3. из которых нижний 3 обыкновенно бывает неподвижным, а верхний 1 — подвижным. Верхний нож 1, опускаясь, давит на металл, прижимая его к нижнему ножу. Оба ножа несколько вдавливаются в металл С врезанием ножей в металл поперечное сечение его уменьшается, появляются вначале мелкие, а затем крупные трещины, и он скалывается.

Под действием ножей на разрезаемый металл часть его, лежащая на столе, приподнимается и поворачивается вокруг грани нижнего ножа. Для предотвращения этого металл прижимается к столу специальным прижимом. Однако при резке металла между ножом и прижимом стремится изогнуться перпендикулярно плоскости резания. Исходя из этого, расстояние между прижимом и режущей кромкой ножа выбирают такое, чтобы изгиб листа был наименьшим.

α – угол раствора ножей; ẞ – угол заострения ножей; ɣ – угол скоса; δ – угол режущей кромки.

Угол скалывания.

Для резки длинного листа металла за один ход ножа необходимо немалое усилие, которое будет тратиться на врезку ножей в металл и на его скалывание. Чтобы снизить потребляемую мощность на все эти операции, ножи устанавливают под углом друг к другу Чем больше будет угол α, тем меньше будет усилие нужное для резки. Так, например, если резать одинаковой толщины листы с наклоном ножей (угол наклона 5°) и без, то разница усилий будет значительной:

– усилие без наклона (с параллельными ножами) 120 т.

Однако нужно заметить, что из-за большого угла наклона ножей создается усилие, которое выталкивает лист из-под ножей. Из-за чего угол наклона устанавливают в пределах от 6 до 8°.

Для того, чтобы облегчить врезку ножей в металл угол реза δ устанавливают меньше 90°, в пределах от 70 до 85°. Для меньшего трения ножей о разрезаемый металл, скашиваются их передние грани на угол от 2 до 3°. Зазор между ножами зависит от толщины разрезаемого металла и допускается не более 0,5 мм.

Ручные рычажные ножницы. Ручные стуловые ножницы.

Резка листового металла вручную осуществляется на ручных, стуловых и рычажных ножницах. Толщина разрезаемого металла обыкновенно бывает небольшой (2—3 мм), но на рычажных ножницах можно резать до 6—10 мм. Длина режущего ножа достигает 350 мм. Ручные ножницы мало производительны, требуют большой затраты мускульной силы рабочего.

Для резки более толстой листовой стали используют гильотинные ножницы и пресс-ножницы. Их ножи приводятся в действие от электродвигателей.

Пресс ножницы для резки металла.

На пресс-ножницах режутся мелкие детали, а также на них можно распускать листы неограниченной длины толщиной до 32 мм. Ножи длиной до 600 мм располагаются вдоль или поперек оси станины. Недостатками у пресс-ножниц являются низкая чистота реза и малая производительность вследствие многократного передвижения листа во время резки больших деталей. Однако ножницы очень удобны при резке мелких деталей.

Высокую чистоту и большую производительность дают гильотинные ножницы. Они состоят из двух, соединенных между собой станин, прикрепленных к рабочему столу. К внутренней кромке стола крепится неподвижный нож, состоящий из отдельных полос, длиной 600—1000 мм.

В пазах станин ходит ползун с присоединенными к нему полосами верхнего ножа. Движение ползуну передается от электродвигателя через коленчатый вал. Для увеличения напора верхнего ножа в рабочем ходе ножницы снабжены тяжелым маховиком, который во время резки расходует большую силу, накопленную при холостом ходе. Разрезаемый лист укладывается на стол ножниц и прижимается к нему прижимами.

Гильотинными ножницами возможна рубка листа толщиной до 40 мм и шириной до 3000 мм. На них можно легко распустить лист на полосы шириной несколько меньшей вылета зева, который у отдельных конструкций ножниц доходит до 600 мм.

Текст книги “Жестяницкие работы. Опиливание и разрезание металла

Разрезанием листового металла называется операция разъединения целого листа, полосы или ленты на части определенной формы и размеров, называемые заготовками.

Различают три способа разрезания листового металла: прямолинейный, криволинейный и смешанный.

Каждый из них может быть единичным или групповым.

Прямолинейное разрезание листового металла выполняют на рычажных, листовых с наклонными ножами и многороликовых ножницах, а также вырубкой в штампах. В результате прямолинейного разрезания листов, полос и лент получают заготовки с прямолинейным контуром, квадрантной, прямоугольной, ромбической и трапециевидной формы.

Криволинейное разрезание листового металла осуществляют на роликовых и вибрационных ножницах, фрезерных станках, а также вырубкой в штампах. В результате криволинейного разрезания листов, полос и лент получают заготовки с криволинейными контурами: круглой, эллипсоидной и других форм.

При смешанном способе разрезания из листов, полос и лент вырезают заготовки, имеющие прямолинейный и криволинейный контур. В результате разрезания листового металла по смешенному способу получают заготовки деталей со сложной формой, например усеченного цилиндра, усеченного конуса и т.д.

При смешанном способе разрезают листовой металл вначале на оборудовании для прямоугольного разрезания, а затем на оборудовании для криволинейного разрезания.

При изготовлении листовых заготовок деталей на фрезерных станках производительность (скорость вдоль линии реза) составляет от 0.5 м/мин при ручной подаче до 2 м/мин при автоматической. При фрезеровании листового металла листы складывают “пакетом”, т.е. несколько листов один на другой. Это увеличивает производительность труда, потому что одновременно обрабатывается несколько деталей. Кроме того, при групповом раскрое деталей на радиально – фрезерных и копировально-фрезерных станках достигается экономия металла.

Холодная штамповка, т.е. вырубка плоских деталей на вырубных штампах, производительнее этого метода и является наиболее экономичным методом изготовления листовых заготовок деталей. На изготовление листовых заготовок деталей холодной штамповкой в среднем затрачивается 0.1-0.2 мин на каждую.

Применение штамповки ограничивается относительной дороговизной штампов, а также сравнительно небольшими размерами деталей.

Резка ножницами

Разрезать листовой металл на отдельные части, вырезать в деталях отверстия, изготовлять детали с криволинейным контуром и выполнять другие подобные работы можно ручными ножницами. В зависимости от расположения режущей кромки лезвия ножниц (справа или слева от нижнего лезвия) они называются правыми или левыми. У правых ножниц скос на нижнем лезвии при резке находится справа, а резка производится по часовой стрелке. У левых ножниц скос на нижнем лезвии при резке находится справа, а резку выполняют против часовой стрелки.

Ручные ножницы изготовляют из углеродистой инструментальной стали У7 или У8. Ножницы состоят из двух половинок, которые изготавливаются цельными или составными с приваркой лезвий. Цельные половинки ножниц изготовляют из углеродистой стали 65, 70. Ручки сварных ножниц изготовляют из углеродистой стали не ниже марки Ст.2, а лезвия – из инструментальной углеродистой стали У7 с термической обработкой их до твердости HRC 52-58. Режущие кромки лезвий остро затачиваются под углом 70-75º и шлифуют. Стандартная длина ножниц составляет 200, 250, 320, 360 и 400 мм, длина лезвий – соответственно 55, 70, 90, 100 и 110 мм. На лезвиях и поверхностях ножниц не должно быть завалов, выхватов, выкрошенных мест, заусенцев, раковин, плен, волосовин, зазубрин и трещин.

Лезвия ножниц должны в закрытом положении взаимно перекрываться, причем перекрытии на концах не должно превышать 2 мм. Обе половины должны соединяться при помощи винта и гайки и обеспечивать плотное прилегание половинок без перекосов и люфта. Ножницы должны резать любым участком режущих кромок. При этом ход их должен быть плавным без заеданий.

Ручные ножницы изготовляют с прямыми и кривыми режущими лезвиями.

Ручные ножницы с прямыми режущими лезвиями применяют для разрезания листов, полос и лент из стали толщиной до 0.7 мм, а из цветных металлов до 1.5 мм по прямым линиям.

Ножницы с кривыми режущими лезвиями применяют при разрезании листов, полос и лент из стали толщиной до 0.6 мм, а из цветных металлов толщиной до 1.2 мм по кривым линиям или при вырезании деталей с комбинацией кривых и прямых линий.

При резке ручными ножницами металла большой толщины можно для уменьшения прикладываемого к ручкам усилия закреплять одну из них в тисках. Если требуется разрезать материал по прямой линии или вырезать округленную фигуру (без резких закруглений) удобнее работать правыми ножницами. В этом случае лучше видна разметочная леска для триммера.

У стуловых ножниц одна кромка загнута и заострена. Ее укрепляют в массивной деревянной подставке или в тисках. От длины другой ручки зависит усилие резки. Стуловыми ножницами разрезают листовой металл толщиной до 2 мм.

Ручные рычажные ножницы позволяют создать большое усилие резания. Этими ножницами можно резать стальные листы толщиной до 4 мм, а листовой цветной металл – толщиной до 6 мм. Разрезаемый лист помещают между нижним ножом и верхним ножом, который приводят в действие рычагом. Ножницы обеспечивают гораздо большую точность обработки, чем обыкновенные ручные и даже стуловые.

Ножницы должны быть остро заточены. Это не только облегчает резку, но и дает возможность получать ровный срез, уменьшая тем самым опасность пореза рук работающего.

Угол заострения лезвий ножниц при резке твердых металлов должен быть в пределах 80-85º, при резке металлов средней твердости – 70-75º, при резке мягких металлов – 65º.

Не рекомендуется раскрывать ножницы слишком широко: они будут выталкивать лист, а не резать. Во время работы между заготовкой и плоскостью резки должен быть прямой угол. Если у ручных ножниц ослаблен шарнир, то для хорошей резки нужно плотно прижимать лезвия ножниц друг к другу.

Разрезают листовой металл ручными ножницами, как правило, по заранее нанесенным на поверхности металла разметочным линиям.

При разрезании листов на широкие полосы левой рукой отгибают отрезаемую полосу, не делая резких перегибов. Это облегчит продвижение ножниц при разрезании и предохранит правую руку от пореза.