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Metal bending and straightening

Straightening of strip and sheet material

Edit strip material. The curved strip is placed on the plate and, holding it with the left hand, the right hand strikes with a hammer on the convex places, hitting first at the edges of the convexity and gradually, as the strip straightens, bringing the blows closer to the middle of the convexity. The work is considered completed when all the irregularities disappear and the strip is straightened.

Rice. 1. Editing of a steel strip on a plate: a - editing acceptance, 6 - checking the results of straightening by eye

Consider for example the editing of a strip 500 X 60 X 10 mm.

It must be done as follows:
a) put on gloves take the strip by the end with your left hand and put it on the plate with the bulge up, right hand take hammer;
b) start dressing by striking with a hammer on the convex parts of the wide side of the strip, turning the strip from one side to the other as necessary; adjust the impact force depending on the size of the strip and the degree of curvature (the thicker the strip and the greater its curvature, the stronger the blows should be); gradually, as the strip is straightened, the force of the blows should be weakened and the straightening should be completed with light blows, often turning the strip from side to side;
c) having finished editing the wide part of the strip, turn the strip onto the edge and, first, with strong, and then with increasingly weak blows, edit here, turning the strip after each blow from one edge to another;
d) check the results of editing by eye (Fig. 73.6), and when high requirements to the straightness of the strip - with an appropriate ruler or on a marking plate.

Editing a thin steel strip bent on an edge is done in a slightly different way. The previous method is unsuitable here, since from hammer blows on a convex rib, a thin strip will bend to the sides, and the places in contact with the plate will be wrinkled.

A thin curved strip is placed on the stove. Having pressed it with the left hand, with the right hand strikes with a hammer in rows along the entire length of the strip, gradually moving from the lower edge to the upper one. In the beginning, the blows must be strong; as they move to the upper edge, they are weakened, but applied more often. With this straightening method, the lower edge gradually stretches more than the upper one, and the strip becomes even.

Rice. 2. Editing a thin steel strip: a - a curved strip (the dashes show the order of impacts, dots show the intensity and strength of impacts), b - straightened strip

Editing is carried out until the lower and upper edges of the strip are straightened along the entire length under the ruler.

Editing sheet material. This operation is somewhat more complicated. The bulges on the sheets of metal in most cases are in the middle or are scattered over the entire surface. If, when editing, strike directly at the bulges, then they will not only not disappear, but even increase. Therefore, the editing of sheets must be carried out so that their edges are stretched accordingly.

For editing, the sheet is placed on the stove and the bulges are circled with chalk or pencil. Supporting the sheet with the left hand, the right hand strikes with a hammer from the edge of the sheet towards the bulge, as shown by the arrows in Fig. 3. Blows should be applied often, but not hard. Under their action, the even part of the sheet will stretch, and the bulge will gradually straighten out. As you approach the bulge, the blows should be delivered more and more weakly.

During editing, you need to monitor the result of the blows: whether the surface of the sheet improves, whether the nicks remain on it from the blows of the hammer, which appear if the hammer is weakly held in the hand.

Sheets with several bulges scattered over the entire surface are straightened, striking first of all in the intervals between the bulges; this stretches the sheet and reduces all the bulges into one common bulge. The last one is straightened out in the usual way, i.e. going from the edges to the middle. Then the sheet is turned over and its straightness is finally restored with light blows of the hammer.

Rice. 4. Editing of sheet material (scheme of striking);

Thin sheets are ruled by wooden hammers. Very thin sheets are smoothed on a smooth and even plate with smooth and even wooden or metal bars.

Rice. 5. Editing thin sheet material: a - with a wooden hammer, b - wooden block

Recently, when straightening metal, the method is used flame straightening, proposed by the Czechoslovak innovator O. Vlah. The usual methods determine the places on sheet material or parts to be straightened. A jet of flame from a gas burner is directed to the marked places, heating the irregularities to a red-cherry color (600-700 °). heated layer of metal high temperature expands, and then, when cooled, under the influence of compressive forces, it straightens. This straightening method increases productivity by almost five times.

Rice. 6. Editing the wire in the fixture: a - general form fixtures: 1 - housing, 2 - pulley, 3 - drive belt, 4 - screws for moving the cams, 5 - manual vice for gripping the wire, 6 - wire, 7 - cams through which the straightened wire passes; b - fixture diagram (section)

Rice. Fig. 7. Straightening of curved shafts: a - screw press for straightening the shaft, b - checking the shaft in fine centers

Correct hydraulic presses for straightening - straightening shafts, axles, pipes

Very often, any type of production raises the question: How can a shaft, a pipe be straightened? How to restore and repair bent and deformed steel? We know the answers to all these questions.

URALSTANKOSERVICE supplies new modern imported straightening presses made in Germany, Italy, and also offers Russian straightening presses own production(produced in Russia).

PURPOSE, APPLICATION AND USE OF THE RIGHT HYDROPRESSERS

Vertical industrial hydraulic presses are designed to eliminate defects in parts in a cold state: deformation, curvature, bends, bending of parts and blanks after improper storage, transportation, after heat treatment, hardening, surfacing, spraying.

The press can be used to repair and restore parts.

Pressing eliminates such defects in workpieces as: convexity, concavity, axial non-linearity and non-flatness, warping, deformation, misalignment of supporting and auxiliary surfaces.

They are used for straightening long and lengthy products and various bodies rotation - axis, shaft, pipe, shaft blanks and tubular blanks, power cylinders, hydraulic cylinders, pneumatic cylinders, rods, rolling rolls, cardan shafts and cardan shafts, stepped shafts, smooth forgings, long screws, rotors, propeller and ship shafts, drill pipes and tubing pipes.

HYDRAULIC PRESS FOR STRAIGHTENING PARTS OF THE AXIS-SHAF TYPE, PIPE WITH A MOVABLE PRODUCT

shape of parts - cylindrical, square, polygonal, screws.

HYDRAULIC PRESS WITH MOVABLE COLUMN FOR straightening and correcting the curvature of parts - manual and CNC

A press moves along the fixed product, which makes the correction in the right place.

occupies a minimum of space in the workshop.

HYDRAULIC STRAIGHTENING PRESS FOR STRAIGHTENING PIPES OR SHAFTS with fixed product and movable press

Portal press - a portal with a cylinder moves along a fixed pipe, with the help of which editing is performed. Takes up minimal space in the workshop.

By special order we will produce an automatic straightening complex with CNC.

Shaft dressing technology

the product or part to be straightened is fixed in a special correcting fixture in which the product can freely rotate around its axis, the product is rotated and the places to be edited are marked.

With a strong bend of the shaft, straightening is carried out with a reverse deflection.

the shaft after straightening should have minimal runouts and deviations.

EDIT OF DETAILS

Editing is the process of eliminating defects that distort the shape of the workpiece by plastic deformation. The workpiece to be edited is called defective. past technological process editing is called rectified.

Machine straightening of products made of metals and alloys eliminates distortion product shape, and also external geometric defects - violation of the correctness of the geometric shape of the cross section - profile.

The curvature may be general in length or local.

Types of curvature:

1. sickle-shaped (crescent)

2. arched

3. twisting

4. waviness

5. warping - this is waviness in the longitudinal and transverse directions - depressions and bulges are of great length

6. curvature - deviation of the axis of a cylindrical product.

7. flatness

8. straightness deviation (convexity and concavity)

Dressing improves the surface quality and accuracy of the geometric shape of rolled products and sheets, shaft-type products (smooth, stepped, crankshafts, etc.) as well as such blanks as: square blanks, hot-rolled round steel, calibrated steel bars, strip blanks.

Also, hot-rolled, thick-walled and thin-walled, cold-rolled, cold-drawn, drill pipes (permissible curvature of 1 mm per 1 meter) are subject to straightening.

Editing is used to correct distortions, warping and leash that appear when:

· heat treatment rolled products, forgings and parts. When the metal is cooled, stresses arise, which deform the part.

· heating during manufacturing and assembly

· violation of loading and unloading technology

· incorrect transportation and storage

Editing provides obtaining workpieces of higher accuracy. Technological processes of machine editing are carried out by methods of plastic bending and tension or compression.

for continuous straightening, roller machines are used, for intermittent straightening, when the curved sections are straightened one by one, hydraulic presses are used.

Billets are straightened in hot and cold condition (cold straightening).

Hot straightening is used to reduce effort.

Correct work is done by a working straightener.

To obtain straight and non-curved parts, correct presses are used with a low plunger speed.

The dressing tool consists of a top punch and an overlay, as well as two movable prisms (dressing prisms).

For dressing, a C-shaped vertical straightening press is usually used. The open space facilitates access when handling long parts. The press consists of a bed, a pump unit and an extended straightening table.

The product to be straightened is fixed in cone centers (fixed or sliding) or rollers - product deflections are controlled by a dial indicator. Rollers are necessary to facilitate the rotation of parts during the straightening process.

Centers and rollers are spring-loaded and can swing on the fingers inserted into the left and right carts, which move freely along the guides of the straightening table, which allows you to edit at a large number of points.

The press distributor connected with a lever is controlled. The straightener can also control the rearrangement of the stops (the distance between the support prisms), the movement of the roller conveyor, and the rotation of the rollers. After adjusting, when the plunger moves up, the springs automatically set the workpiece to the control position.

The corrector during editing should not allow excessive bending of the part.

The straightener checks the quality of editing with the help of an indicator head for runout on the controlled surfaces.

the right tool, the right tool.

the supply of blanks under the press is carried out along a roller conveyor with driven or non-driven rollers.

in the case of heated straightening, a furnace is installed next to the press, because with an increase in temperature, plasticity increases, and strength and resistance to deformation decrease.

During the pressure straightening process (plastic deformation), the microstructure and macrostructure of the workpiece changes.

The editing force depends on cutting off the workpiece, the distance between the supports.

If the dressing force is insufficient - the bend may be elastic - in this case, the workpiece, after removing the load, will restore its original shape and dimensions - this phenomenon is called springback.

The harder the metal and the higher its yield strength, the greater the springback.

Therefore, it is necessary that the force of the correct press be higher than the yield strength of the deformed metal - by 0.25-1%.

When editing, elastic and plastic deformations occur - elastic deformation appears in the form of inverse elastic deformation.

In order to straighten a curved section, it is necessary not only to unbend it, but also to bend it somewhat. reverse side- give it a reverse curvature, given that after the load is removed, springback will occur and the area will become almost flat. hot dressing- no springing.

QUALITY CONTROL

During this operation, the geometric shapes of the product are checked. Those products are considered suitable if the dimensional deviations are within the tolerances specified by technologists for subsequent machining.

For round shafts and cylindrical parts - by rotating the product and the indicator head, the beating of the surface is checked - concavity is equal to half the amplitude of the indicator readings.

The correctness of the shape of finished blanks can be determined visually by eye or using templates and measuring tools.

When equipping the press with electronic measuring systems and sensors, information from them can be transferred to the CNC system for further processing.

STRAIGHTENING OF FLAT AND SHEETS, SHEETS AND SHEET

Long sheets, rolled leaves are straightened on multi-roll sheet straightening machines (rollers for straightening). The part to be straightened is passed through the rolls several times.

For editing small workpieces, editing is applied to hydraulic presses in a straightening (straightening) stamp. The stamp consists of 2 massive plates - one plate is mounted on the table, the other is on the slider. The working surfaces of the die plates are made of three types: smooth (used with low requirements for the quality of dressing), point (for thick workpieces), wafer (for parts of small thickness).

For dressing short cylindrical parts, it is possible to use two-roll dressing - between two rollers rotating in the same direction, the rollers rotate relative to each other at different speeds.

Services of our company: repair of hydraulic presses, modernization of hydraulic presses, rigging work on presses, dismantling, installation of new equipment, production of new special presses, development according to customer requirements, design of non-standard presses.

Yekaterinburg, Pervouralsk, Kamensk-Uralsky, Nizhny Tagil, Chelyabinsk, Miass, Zlatoust, Magnitogorsk, Orsk, Kurgan, Orenburg, Tyumen, Ufa, Kazan, Izhevsk, Kirov	free shipping
Nizhny Novgorod, Vladimir, Cheboksary, Penza, Tambov, Samara, Saratov	delivery cost 70.000 rubles
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Moscow, Kaluga, Ryazan, Tver, Smolensk, Bryansk	delivery cost 95.000 rubles
Kazakhstan	delivery cost 100.000 rubles
Krasnodar, Rostov-on-Don, Stavropol, Taganrog	delivery cost 120.000 rubles
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Metal dressing

Editing is used in cases where it is necessary to eliminate the distortion of the shape of the workpiece - waviness, warping, dents, curvature, bulging, etc. The metal can be edited both in cold and heated form. Heated metal is easier to edit, which is also true for other types of its plastic deformation, for example, bending.

At home, dressing should be done on an anvil or a massive plate of steel or cast iron. Working surface plates must be flat and clean. To reduce the impact noise, the hob should be installed on wooden table, with which, in addition, it is possible to level the plate so that it is in a horizontal position.

For editing, you need a special locksmith tool. You can’t produce it with any hammer that is at hand, the metal can not only not straighten out, but also get even bigger defects. The hammer must be made of soft material- lead, copper, wood or rubber. In addition, you can not rule the metal with hammers with a square head: it will leave traces in the form of nicks on the surface. The hammer head should be round and polished.

In addition to hammers, wooden and metal trowels and supports are used. They are used for straightening thin sheet and strip metal. For dressing hardened parts with shaped surfaces, there are correct headstocks.

It’s probably not worth reminding that metal straightening (straightening) must be done in work gloves, regardless of whether hard work or not, whether the workpiece is large or small, and whether it is severely warped.

To check the curvature of the workpiece, you need to lay it on a smooth plate with that surface, which, after straightening, should be a plane. The gap between the plate and the workpiece will indicate the degree of curvature that needs to be eliminated. Curved places should be marked with chalk - it is much easier to strike with a hammer than when focusing only on the curvature noticeable to the eye.

Editing of strip metal bent in a plane, is the simplest operation. The curved workpiece must be positioned so that it has two points of contact with the anvil. Hits with a hammer or sledgehammer should be applied to the most convex places and reduce the force of blows as the bulges become smaller. Do not strike only on one side of the workpiece - the metal may bend in the opposite direction. To prevent this from happening, the workpiece must be turned over from time to time. For the same reason, you should not strike several blows in a row in the same place.

If there are several bulges, you must first straighten the edges of the workpiece, and then its middle.

Editing of round metal. This kind of work is basically similar to straightening strip metal. To do this, mark uneven places with chalk and place the workpiece with the bulge up, apply blows to the convex part from the edges of the bend to the middle of the bulge. When the main curvature is corrected, the force of impacts must be reduced and periodically rotated metal rod around its axis to prevent curvature in the opposite direction.

metal rods square section must be done in the same order.

Editing of metal twisted in a spiral, produced by the spinning method. In order to straighten the curvature, you need to clamp one end of the twisted metal into a large vice on locksmith's table, the other - in hand vise. Having untwisted the metal to the extent that can be controlled by eye, you need to continue editing on a smooth, verified plate conventional method, controlling the curvature through the light.

Sheet metal dressing

The complexity of straightening sheet metal depends on what type of defect the sheet has - waviness of the edge, or a bulge, or a dent in the middle of the sheet, or both at the same time (Fig. 15).

Rice. 15. Techniques for straightening sheet metal: a - with a deformed middle of the sheet; b - with deformed edges of the sheet; c - using a wooden trowel; d - using a metal trowel.

When editing the bulge, it is necessary to strike, starting from the edge of the sheet towards the bulge (Fig. 15 a, b).

The most common mistake is that the heaviest blows are applied to the place where the bulge is greatest, and as a result, small dents appear on the bulge area, which further complicates the uneven surface. In addition, the metal in such cases experiences a very strong tensile strain. You need to do just the opposite: the blows should become weaker, but more often, as the edit approaches the center of the bulge. The sheet of metal must be constantly rotated in a horizontal plane so that the blows are evenly distributed over its entire surface.

If the sheet has more than one convex section, but several, you must first reduce all the convexities into one. To do this, strike with a hammer in the intervals between them. The metal between the bulges is stretched, and they are combined into one. Then you need to continue editing in the usual way. If the middle of the sheet is even, and the edges are distorted by waves, then the sequence of blows during editing should be the opposite: they should be applied starting from the middle, moving towards the curved edges (Fig. 15, b). When the metal in the middle of the sheet is stretched, the waves at its edges will disappear.

Very thin sheets cannot be corrected even with mallets made of soft material: they will not only leave dents, but can also tear thin metal.

In this case, ironing bars made of metal or wood are used for editing, with which the sheet is smoothed on both sides, periodically turning it. The quality of editing can be controlled using a metal ruler.

Anyone who has taken on the straightening of a steel sheet knows that this is a rather difficult job: while straightening one bend, others appear on the sheet. However, this can be avoided and thus significantly facilitate the work. The steel sheet must be laid for straightening not on a smooth slab, as is usually done, but on a backing slab with many small blunt bumps evenly spaced on its surface. In this case, the quality of work should increase, and the labor intensity should decrease. Metal under the blows of a rubber hammer will, as it were, look for its own place. At the same time, barely noticeable waves are formed on the sheet; during puttying and painting, they will begin to fill up and contribute to the fact that the putty and paint will adhere to the metal very firmly. Irregularities after coating the metal are completely invisible. The only difficulty is how to make the required lining plate. It is really difficult to make it at home: tubercles are usually obtained by cutting through smooth plate big number mutually intersecting and closely spaced grooves. You can do this on a planer or milling machine, so if there is such an opportunity, it is better to use it.

Editing of hardened metal (straightening)

Soft dressing hammers are unsuitable for straightening hardened metal (straightening). A special hammer with a hardened metal head or with a rounded narrow side is required. You can make a straightening hammer yourself. To do this, it is necessary to make a slot in the narrow head of the hammer and tightly press into it a plate of hard alloy VK6 or VK8, sharpened under a radius of 0.1–0.2 mm.

Hardened metal is corrected by the reverse method: strikes must be applied not to the convex, but to the concave section of the workpiece: it will begin to straighten due to the fact that the metal on the concave side will stretch (Fig. 16).

Rice. 16. Editing of hardened metal (straightening): a - strips; b, c - squares.

Straightening is more convenient to produce not on flat plate, but on a special straightening headstock, which has a convex surface, moving the workpiece up and down along it.

An unsolvable task for an inexperienced locksmith is to edit a flat square, in which the angle has changed and has become more or less than 90 °. Such squares are no longer suitable for checking right angles, and, as a rule, they are thrown away. Meanwhile, the hardened metal square can be straightened. If the right angle has decreased and is less than 90 °, then hammer blows must be applied along the plane of the square at the top inner corner. If the angle has increased and exceeds 90°, strikes should be applied at the top outer corner.

After the metal is straightened, you can proceed to its further processing.