In his practical work, a locksmith is often faced with straightening metal of a particular profile or straightening workpieces.
Editing is a preparatory operation. It can be done in two ways: mechanically - using straightening rolls, presses and various devices, and manually - using a hardened steel hammer, sledgehammer, anvil or plate and an auxiliary tool - a trowel.
At manual editing it is better to use a hammer with a round face to prevent nicks and dents on the surface of the straightened workpieces. The surface of the hammer head must be carefully sanded.
For dressing parts with a finished surface, as well as thin steel products or workpieces made of non-ferrous metals and alloys, hammers made of soft materials are used - copper, brass, lead, wood.
When straightening thin wire and thin strip and sheet metal, metal and wooden mandrels, floats and gaskets are used.
Editing of strip and sheet material. When editing a curved strip, the latter is held with the left hand and, on an anvil or plate, strikes with a hammer on the convex places of the wide side of the strip, turning the strip from one side to the other as necessary.
The impact force is adjusted depending on the magnitude of the curvature and the thickness of the strip.
After finishing the editing of the wide part of the strip, they begin to edit the rib, first with strong blows, and then with weak ones, turning the strip after each blow from one edge to another.
Checking the straightened strip is done by eye, and more precisely - with a ruler or on marking plate.
Editing of thin strip steel is carried out in a different way, 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 stick together.
A thin strip is corrected on a plate: pressing it with the left hand, with the right hand strikes with a hammer along the entire length of the strip, gradually moving from the lower edge to the upper one, as indicated in Fig. 69.
In the beginning, the blows should be strong, and as you move to the upper edge, they should be weaker, but more often applied. Such editing helps to stretch the lower edge, and the strip becomes even.
Editing sheet material is a more complicated operation, since the bulges on the sheets in most cases are in the middle or scattered over the entire surface of the sheet, and when you hit the convex parts with a hammer, the latter will not only not decrease, but even increase in size.
Therefore, editing sheet material should be carried out as follows:
The sheet is placed on the stove and the bulges are outlined with chalk or pencil. While 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 in Fig. 70 arrows. Blows should be applied frequent, but not strong. Under the influence of such blows, the flat part of the sheet will increase, and the bulge will gradually straighten.
As you approach the convexity, the blows should be made more often and weaker, at the same time it is necessary to monitor whether the surface of the sheet improves, whether there are traces of hammer blows on it and whether the convexity is eliminated.
If there are several bulges on the sheet, then blows should be applied in the intervals between the bulges, as a result of which the sheet is stretched and all the bulges are reduced to one common bulge, which is straightened in the usual way, i.e., going from the edges of the bulge to the middle. After that, the sheet is turned over and with light blows of the hammer, its straightness is finally restored.
Very thin sheets are leveled on a flat and smooth plate.
Straightening of bar material and shafts. Long rods and wires are straightened by passing through dies in broaching machines or through rotating rollers in a special straightening machine, or by hand on a plate. Short workpieces are also ruled in this way. Checking the straightness of bars and blanks is carried out on the plate or by eye.
Shafts and workpieces of large cross section are straightened on a manual or mechanical press, for which the shaft or workpiece is installed on the prisms of the press table with the convex part up. The distance between the prisms is adjustable.
Usually it fluctuates between 150 - 300 mm. Editing is carried out by pressing the screw on the convex part of the shaft.
Shafts of large cross-section and with a significant deflection are preheated in places of maximum deflection.
Checking the shaft after dressing is carried out in centers mounted on a separate table or plate, as indicated in Fig. 71.
Editing hardened parts. Warped steel parts or blanks after hardening are ruled by special steel hammers, shock part which has the shape of a machinist's hammer, carefully finished, without sharp corners and well hardened. The dressing plate must have a smooth ground surface (flat or convex), the hardness of which must not be lower than the hardness of the hammer head.
Hammer blows should be applied not to the convex part of the hardened part, but to the concave part. In this case, the blows should not be strong, but frequent.
For example, let's take a look at several cases of straightening hardened parts.
The part is placed on the convex surface of the plate and, holding it with the left hand, apply light but frequent hammer blows to the concave part, starting from the most concave part and gradually moving to the place where the deflection ends.
At the same time, the part is turned by 15 - 20 ° with the left hand, either in one direction or the other, and moved towards itself. Thus, the impacts are distributed over the concave surface of the sector with an angle of 30 - 40°.
As a result of this, the fibers of the concave part of the part seem to be distributed, stretched from hammer blows, and in the convex part they are compressed and the part is leveled.
In a similar way, the hardened strip of the ruler is corrected (Fig. 72).
In case when flat piece has cutouts, for example, a bracket, a template, then during hardening it warps (both along the plane and along the edge), and therefore editing should be carried out in the following sequence:
The template is placed with the convex part on the plate and held with the left hand at one end, and with the right hand, frequent, but not strong blows are applied to the concave part with the toe of the hammer, starting from the middle and gradually moving to the edge. Then, taking the opposite end of the template with your left hand, continue editing the second part of the template in the same sequence.
After editing the plane, they start editing along the edge. In this case, the template or bracket is pressed against the plate with the left hand, and the right hand strikes with the toe of the hammer from the side of the concave part from the middle to the edge alternately on both sides (Fig. 73).
Dressing hardened rollers and spindles with a diameter of 20 mm and above are usually produced by a hand press by pressing the press screw on the convex part of the part.
Sheet metal dressing performed to give the workpieces the correct geometric shape without bulges, bumps, kinks and dents. Curvature can be corrected manually or on straightening machines, presses. Automatic straightening is more productive and efficient, especially in mass production. Manual editing of the sheet is used in repair shops, when performing small or single orders.
The site presents enterprises that carry out both automatic editing and manual editing.
Features of straightening sheet metal
The dressing operation is based on the property of metals to deform under pressure. It can be applied to blanks made of metals with good plastic properties, otherwise the metal will be destroyed during processing. The dressing operation is carried out with a thermal effect on the metal - hot way, or without it - a cold way.
Sheet metal dressing done manually with a hammer or wooden mallet and an anvil or steel/cast iron plate. This is a laborious operation, which has its own characteristics. So, the surface of a sheet of metal should lie on the anvil or plate over the entire area. Irregularities must first be noted with a pencil. Hammer blows are applied in the direction from the edge of the sheet to the bulge in order to avoid greater elongation. As you approach the bumps, the impacts should be more frequent, but less strong. Manual editing is also carried out with special keys, on correct plate with pins and squares.
Sheet metal dressing on straightening machines, rollers and presses. Small and medium workpieces are dressed on roller machines with different numbers of rollers. Sheets are rolled through rollers staggered at the top and bottom. Large-sized sheets are corrected on horizontal stretching machines, where metal fibers are aligned due to stretching.
Metal dressing
To category:
Metal bending and straightening
Metal dressing
The curvature of the parts is checked by eye or by the gap between the plate and the part laid on it. The edges of the curved places are marked with chalk.
When editing, it is important to choose the right places to hit. The force of impacts should be commensurate with the amount of curvature and gradually decrease as you move from the greatest bend to the smallest. Editing is considered complete when all irregularities disappear and the part becomes straight, which can be determined by applying a ruler. Editing is carried out on an anvil, a regular plate or reliable linings that exclude the possibility of parts slipping from them upon impact.
To prevent hands from shocks, vibrations when straightening metal, it is necessary to wear gloves, firmly hold the parts, workpieces on the plate or anvil.
Editing of strip metal is carried out in the following order. On the convex side, the boundaries of the bends are marked with chalk, after which on left hand put on a mitten and take a strip, and in right hand take a hammer and assume a working position.
The strip is placed on a regular slab so that it lies flat on the slab with a convex upwards, touching at two points. Impacts are applied to the convex parts, adjusting the impact force depending on the thickness of the strip and the magnitude of the curvature; the greater the curvature and the thicker the strip, the stronger the blows. As the strip is straightened, the impact force is weakened and more often the strip is turned over from one side to the other until it is completely straightened. With several bulges, first straighten those closest to the ends, and then located in the middle.
The results of editing (straightness of the workpiece) are checked by eye, and more precisely, on a marking plate along the clearance or by applying a ruler to the strip.
Editing a bar. After checking by eye on the convex side, the boundaries of the bends are marked with chalk. Then a bar is placed on a slab or anvil (Fig. 1) so that the curved part is convex upwards. Hammer blows are applied on the convex part from the edges of the bend to the middle part, adjusting the impact force depending on the diameter of the rod and the size of the bend. As the bend is straightened, the impact force is reduced, finishing with light blows and turning the bar around its axis. If the bar has several bends, first those closest to the ends are corrected, then those located in the middle.
Rice. 1. Editing of round metal
Rice. Fig. 2. Scheme of straightening sheet material: a, b - bent blanks, c. d - distribution of shocks
Sheet metal dressing is more complex than previous operations. Sheet material and blanks cut from it may have a wavy or bulged surface. On workpieces with waviness along the edges (Fig. 2, a), the wavy areas are first outlined with chalk or a soft graphite pencil. After that, the workpiece is placed on the plate so that the edges of the workpiece do not hang down, but lie completely on the supporting surface, and pressing it with a hand, they start straightening. To stretch the middle of the workpiece, hammer blows are applied from the middle of the workpiece to the edge as indicated in Fig. 2, in circles. Circles of smaller diameters correspond to smaller strokes, and vice versa.
Stronger blows are applied in the middle and the force of the blow decreases as it approaches its edge. In order to avoid the formation of cracks and work hardening of the material, it is impossible to apply repeated blows to the same place of the workpiece.
Particular care, attention and caution are observed when straightening blanks from thin sheet material. They apply light blows, since with an incorrect blow, the side faces of the hammer can either pierce the sheet blank or cause the metal to be drawn out.
Rice. 3. Editing thin sheets: a - with a wooden hammer (mallet), b - with a wooden or metal bar
When straightening blanks with bulges, warped areas are revealed, and it is established where the metal is more bulged (Fig. 2). The convex sections are outlined with chalk or a soft graphite pencil, then the workpiece is placed on the plate with the convex sections up so that its edges do not hang, but lie completely on the supporting surface of the plate. Editing begins from the edge closest to the bulge, along which one row of hammer blows is applied within the limits indicated on the surface covered with circles (Fig. 2, d). Then they strike on the second edge. After that, a second row of blows is applied along the first edge and again they go to the second edge, and so on until they gradually approach the bulge. Hammer blows are applied often, but not strongly, especially before the end of the edit. After each impact, its impact on the workpiece at the site of impact and around it is taken into account. Do not allow multiple blows to the same place, as this may lead to the formation of a new convex area.
Under the blows of the hammer, the material around the convex place is pulled out and gradually leveled off. If there are several bulges on the surface of the workpiece at a small distance from each other, with hammer blows at the edges of individual bulges, these bulges are forced to connect into one, which is then ruled by blows around its boundaries, as indicated above.
Thin sheets are ruled with light wooden hammers (mallets - Fig. 3, a), copper, brass or lead hammers, and very thin sheets are placed on a flat slab and smoothed with metal or wooden bars (Fig. 3, b).
Straightening (straightening) of hardened parts. After hardening, steel parts sometimes warp. The straightening of parts that are bent after hardening is called straightening. The straightening accuracy can be 0.01-0.05 mm.
Depending on the nature of the straightening, hammers with a hardened striker or special straightening hammers with a rounded face are used.
Rice. 4. Straightening of hardened parts: a - on the straightening headstock, b - square along the inner corner, c - along the outer corner, d - places of impact
lazy side of the striker. In this case, it is better to place the part not on a flat plate, but on a straightening headstock (Fig. 4, a). Impacts are applied not on the convex, but on the concave side of the part.
Products with a thickness of at least 5 mm, if they are not hardened through, but only to a depth of 1-2 mm, have a viscous core, so they are straightened relatively easily; they need to be straightened as raw parts, i.e., strike at convex places.
Editing a hardened square, in which, after hardening, the angle between the shelves has changed, is shown in fig. 4, 6-g. If the angle has become less than 90 °, then hammer blows are applied at the top of the inner corner (Fig. 84 b and d, left), if the angle has become more than 90 °, blows are applied at the top of the outer corner (Fig. 4, c and d, right) .
In the case of warpage of the product along the plane and along a narrow rib, straightening is performed separately - first along the plane, and then along the rib.
Editing of short bar material is carried out on prisms (Fig. 5, a), regular plates (Fig. 5, b) or simple linings, striking with a hammer on convex places and curvatures. Having eliminated the bulges, straightness is achieved by applying light blows along the entire length of the bar and turning it with the left hand. Straightness is checked by eye or by the gap between the plate and the bar.
Rice. 5. Editing of short shafts and bars: a - on prisms, b - on a plate
Strongly springy and also very thick workpieces are dressed on two prisms, striking through a soft pad to avoid nicks in the workpiece. If the forces developed by the hammer are insufficient for straightening, manual or mechanical presses are used.
Editing (straightening) is an operation by which irregularities, curvature or other imperfections in the shape of workpieces are eliminated. Editing and straightening have the same purpose, but differ in the methods of execution and the tools and devices used.
Editing is the straightening of metal by the action of pressure on one or another part of it, regardless of whether this pressure is produced by a press or by hammer blows. „
Dressing is, as a rule, a preparatory operation that precedes the main operations of metal processing.
Editing is subjected to steel sheets and sheets of non-ferrous metals and their alloys, strip, bar material, pipes, wire, as well as metal welded structures. Workpieces and parts made of fragile materials (cast iron, bronze, etc.) cannot be edited.
There are two methods of dressing metals: manual dressing, performed with a hammer on steel cast-iron straightening plates, anvils, etc., and machine straightening, performed on straightening machines. When manually straightening, the locksmith searches for places on the surface of the workpiece or part, upon impact on which the workpiece would be straightened, that is, it would lie on the plate, without bulges, bends or waviness.
The metal is straightened both cold and hot. In the latter case, it must be borne in mind that the straightening of steel billets and parts can be carried out in the temperature range of 1100-850 °C. Heating above the specified temperatures leads to overheating, and then to burnout of the workpieces, i.e., to an irreparable marriage.
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, however, this 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. The working surface of the stove must be flat and clean. In order to make the impact noise less loud, the stove 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.
Editing requires a special metalwork tool. You can’t produce it with any hammer that is at hand, the metal can not only not straighten out, but get even bigger defects. The hammer should be made of soft material - lead, copper, wood or rubber. In addition, it is impossible to edit metal with hammers with a square striker - it will leave traces in the form of nicks on the metal 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 grandmas.
It is probably not worth reminding that metal straightening (straightening) must be done in work gloves, regardless of whether the work is difficult or not, whether the workpiece is large or small, and whether it is strongly curved.
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 must be marked with chalk, so it is much easier to strike with a hammer than focusing only on the curvature noticeable to the eye.
Straightening 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 into reverse side. 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.
Straightening round metal - this type of work is basically similar to straightening strip metal - you need to mark uneven places with chalk and place the workpiece with the bulge up, blows should be applied to the bulge 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 the metal rod periodically rotated around its axis in order to prevent curvature in the opposite direction.
Metal bars of square section must be edited in the same sequence.
Editing of metal twisted in a spiral is carried out by the method of unwinding. In order to straighten the curvature, you need to clamp one end of the twisted metal into a large vise on the bench table, the other into 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 in the usual way, controlling the curvature through the light.
DURING THE CLASSES
Plan
1. Editing of metal.
2. Tools and fixtures used in straightening metal.
3. Basic rules for performing work when straightening metal.
4. Typical defects in metal dressing, their causes and prevention methods.
5. Safety rules for metal straightening.
We must learn to do everything so well
as soon as we can, and identify our mistakes.
Karl Raymond Popper
Hello dear students!
Before proceeding directly to the subject of our consideration, this is an acquaintance with the technology of straightening metal, let me tell you a little about the organization of labor, about
how to equip workplace which tools to choose and which ones to use
materials. So, let's begin….
Workplace equipment is far from the last thing, although many often do not
do not pay attention to this point. It doesn't matter what you have available, be it
a small box of tools or a whole workshop - order should be everywhere. And
how quickly you find the tool you need depends on the speed of execution
one job or another. And besides, it is much more pleasant when everything is in its place and
always at hand.
Rolled metal products, pipes and sheet steel due to incorrect transport practices
and storage are warped, bent. To eliminate these defects,
Edit- This is an operation to straighten a bent or warped metal, which can only be subjected to ductile materials: aluminum, steel, copper, brass, titanium.
There are two types of metal straightening: cold straightening and hot straightening. Editing is carried out
on special right plates, which are made of cast iron or steel.
Editing small parts can be done on blacksmith anvils. Edit
metal is carried out with hammers of various types depending on the condition
surface and material of the part being dressed.
When dressing workpieces with a raw surface, hammers are used with
round strikers weighing 400g. A round head leaves fewer marks on the surface than a square one.
When dressing workpieces with a treated surface, hammers are used that have strikers with soft inserts (made of copper, aluminum), which do not leave marks on the surface. When editing sheet material, wooden mallets are used, and very thin sheets are ruled with wooden or metal bars - trowels.
Editing is carried out in several ways: bending, stretching and smoothing.
Editing by bending used for straightening round (rods) and shaped material, which
have a fairly large cross section. In this case, hammers with steel heads are used. The workpiece is placed on the correct plate with the bend upwards and blows are applied to the convex places, bending the workpiece in the direction opposite to the existing bend. As the workpiece is straightened, the impact force is reduced.
Pull edit used when straightening sheet material having bulges
or waviness. Such editing is carried out with hammers with soft metal strikers or mallets. In this case, the workpiece is placed on a regular plate with the bulges up and frequent light blows are applied, starting from the border of the bulge, towards the edge of the workpiece. The strength of the blows gradually decreases. In this case, the metal is stretched to the edges of the workpiece and the bulge is straightened due to this stretching.
Editing by smoothing used in cases where the workpiece has a very small thickness. Smoothing is carried out with wooden or metal bars. The workpiece is smoothed on the correct plate, pulling the material with the help of trowels from the edge of the unevenness to the edge of the workpiece, and by pulling the material, the surface of the workpiece is leveled.
Tools and fixtures used in editing
Correct slabs made of gray cast iron with working surfaces
1.5×5.0; 2.0×2.0; 1.5×3.0; 2.0×4.0m. On such plates, profile blanks are corrected and
blanks from sheet and strip material, as well as bars from black and non-ferrous
Leveling grandmas used for straightening workpieces made of
metals high hardness or pre-hardened metals.
Leveling headstocks are made from steel billets with a diameter
200..250mm, their working part has a spherical or cylindrical shape.
Hammers when editing, they are used to apply force
effort at the place of editing. Depending on the physical and mechanical
properties of the workpiece to be processed and its thickness are chosen
different types hammers. When straightening blanks from bar and
strip material, hammers with square and round
Soft hammers are used for dressing machined surfaces.
inserts made of aluminum and its alloys or copper.
Sledgehammers are hammers of large mass (2.0 ... 5.0 kg) and
are used for straightening round and shaped rolled products of large transverse
sections in cases where the force of impact applied by a conventional metalwork hammer,
insufficient to straighten the deformed workpiece.
mallets- these are hammers, the impact part of which is made of solid wood
rocks, they are ruled by sheet material made of metals of high ductility.
Feature mallet corrections in that they practically do not
leave traces on the straightened surface.
Ironers metal or wooden (hardwood: beech, oak,
boxwood) are intended for straightening (smoothing) sheet material
small thickness (up to 0.5 mm). This tool is in the process of being processed
as a rule, does not leave traces in the form of dents.
During processing, storage or operation, metal parts and blanks may lose their original shape.
To perform subsequent operations, to maintain the dimensions and shape of the finished product, it is important that the configuration and dimensions of the workpiece match the design values. This is achieved by an intermediate preparatory operation of straightening the metal. The operation is carried out on a cold part or it is heated for the purpose of plasticity.
The sheet blank may be wrinkled, having a cylindrical shape - bent. Shafts and axles can bend.
What is metal straightening?
The process of returning a metal blank to its original shape is called metal straightening. Defects are as follows:
- Wave.
- Dent.
- Convex.
And also some others.
Types of metal dressing
The operation is divided into two subspecies:
- Manual.
- Machine.
Manual editing and straightening of metal is used in home workshops and in the manufacture of unique products. The set of tools is simple, but a high qualification of a worker - a straightener is required.
Machine straightening is used in industry. The equipment is massive and complex, but has high productivity and process automation capabilities. In addition, the operation of machine straightening is often combined with bending and cutting of sheet blanks, including it as part of a single technological complex.
The operation can be carried out at room temperature. Work at a temperature of 0C and below is unacceptable - the material loses its plasticity and becomes brittle. Sometimes the workpiece has to be heated to 140-400C in order to increase plasticity.
Sheet metal dressing
The complexity of the sheet metal straightening operation also depends on the type of defect.
The most difficult cases are the combination different types defects, for example, waviness of the edge and a bulge in the center of the sheet at the same time.
Convex
The bulge is corrected by blows on the circumference, starting from the outer side of the defect and gradually reducing the radius of the circle, moving from the edge to the center of the defect. The force of the blows becomes less, and the frequency increases.
If there is more than one bulge on the workpiece, they should be combined into one large one. It is necessary to beat between local defects, achieving their association, and then proceed as described above.
Wavy edges
Editing of sheet metal with wavy edges is carried out starting from the edges of the sheet and gradually moving towards its center. After stretching the workpiece in the middle, the waviness of the edges is smoothed out.
Thin sheets
Workpieces of small thickness cannot be straightened with dies due to the high probability of ruptures and creases.
For editing sheet metal use extended surfaces of metal or wooden trowel bars. The workpiece is smoothed from different sides, gradually increasing the pressure.
Periodically it is necessary to turn the strip over so that there is no bulge in the other direction. If there are several bulges at the beginning, straighten the ends of the strip, and then move on to the middle.
Soft strikers are not used for straightening. They are made of high-strength alloy and rounded or rounded off the sharp side.
To straighten the hardened metal, blows are directed along the concave section of the part. As the material stretches on the concave side, the workpiece will straighten out. The operation is carried out on a hemispherical straightening headstock, along which the part is gradually moved up and down.
To straighten a hardened square with a violation right angle developed two approaches. If the corner has become sharp, strikes are directed near the inner corner. If the corner has become obtuse, the blows are directed to the zone at the top of the outer corner. The material in the affected area is stretched and the right angle is restored.
The method is similar to working with a strip. Irregularities are marked with chalk, the workpiece is located with a bulge up. Impacts are directed from the periphery of the defect to its center.
When the main defect is corrected, the impact power is reduced and the part is rotated around the longitudinal axis in order to avoid deformation in the other direction. Square and rectangular rolled products are corrected in the same way.
Here, the spin method is used. One end of the spiral is fixed in a vice fixed on the correct plate, the other in a manual clamp.
After partial untwisting of the spiral, it is pressed against the plate and corrected like a round rolled product, determining the curvature through the light.
The main methods of straightening metal
The choice of method is influenced by the nature and area of the section, the brand and type of alloy, the size of the defect relative to the overall size of the product.
Depending on the method of applying stresses in metal blanks, there are three ways of straightening metal:
- cold bending;
- stretching in a cold state;
- local heating.
Heating is carried out by gas burners or induction.
What is the purpose of metal cutting?
The configuration of a part can be changed during its primary processing, transportation or storage. Such blanks are unsuitable for further use, but are not irrevocable, final marriage. Metal dressing is used in order to return the form to the workpiece, determined by the design and technological documentation.
Sometimes, in order to reduce the cost of production, an enterprise intentionally acquires blanks of improper shape, in this case the operation is included in the technological process. Planned editing of metal can also be included in the process after heat treatment operations that cause a change in the shape of the part. Otherwise, the work will be unscheduled, and its cost is included in unplanned losses.
Straightening equipment
The basis of any set of tools is the right stove. It must be perfectly even, massive and stable, for which it is cast from high-impact cast iron or steel, to strengthen the structure, it is provided with longitudinal and transverse stiffeners. They are installed on a massive concrete base.
Dressing hammers should be softer than the workpiece material. Therefore, they are supplied with wooden or rubber strikers. To work with steel sheets, hammers with soft heads made of copper or lead are used. The striker must have a rounded shape. A square-shaped striker is not suitable, as it will leave characteristic traces on the sheet blank - nicks. The mass of the plate should be related to the mass of the hammer approximately 100:1.
To work with a sheet blank, a backing plate made of dense rubber is also used, with a big amount tubercles of the same height. Under impact, the metal finds its place on its own, and the productivity of the process is noticeably increased compared to a bare steel straightening plate.
To work with thin sheets, special equipment is used - trowels and supports. To work with hardened parts, cylindrical or hemispherical straighteners are used.
In the home workshop, an anvil or a massive metal plate is used.
The enterprises use special mechanized straightening complexes with mechanical sheet feeding and automated correction of defects. In some, the billet is pulled between massive counter-rotating rolls. In others, the operation takes place on the correct platen by lowering a wide press.