EQUIPMENT AND DEVICES FOR STRAIGHTENING

§ 1. MAIN TYPES AND APPLICATIONS OF EQUIPMENT

Editing can be carried out both on specialized equipment and on equipment general purpose. The choice of one or another type of equipment or machine is determined by many conditions, which include the nature (serial, single) and features of the production technology, the type of products produced, technical requirements presented to it, productivity and economic feasibility of using a certain type of equipment, etc.

For straightening rolled products, mainly four types of straightening machines are used: straightening presses with a mechanical or hydraulic drive; roller grade and sheet straightening machines, machines for straightening bars and tubes with oblique rollers; stretch straightening machines.

Correct presses are mainly used for straightening large-section rolled products (round, square, and other profiles), large beams, channels, and pipes with a diameter of more than 200-300 mm. In addition, they perform additional editing of rails that are not straightened on roller straightening machines. Sometimes small-section rolled products are corrected on small-capacity presses. Cold straightening of thick sheets and strips is carried out on specialized sheet straightening hydraulic presses.

On the Roller straighteners are used to straighten fine and medium-sized steel different profiles, and on roller straightening machines - sheets, strips and tapes of small thicknesses.

Sheet straightening, especially from special steels and alloys, as well as from non-ferrous metals and alloys, is successfully performed on stretching straightening machines.

Rotary skew and stretch straightening machines are also widely used for straightening pressed pipes and bars of simple and complex profiles.

Forgings made by free forging are usually ruled on the main forging equipment - large forgings on hydraulic presses, small ones on steam-air and pneumatic forging hammers. In rare cases, after heat treatment, large forgings or parts from them are corrected on special presses. Stamped forgings, if necessary, are corrected depending on the production conditions on a wide variety of forging and pressing equipment, as well as on specialized straightening automatic and semi-automatic machines and presses. Parts stamped from a sheet are corrected on mechanical presses various designs.

§ 8. Stretching straightening machines. MACHINE FOR STRAIGHTENING STRIPS AND PARTS COMBINED WITH ELECTRICAL RESISTANCE HEATING

Stretch the right cars. Stretch straightening is used for bars and pipes of shaped section, obtained by pressing (extrusion through a matrix), and for sheets high quality. By pressing, shaped bars and pipes are obtained from aluminum and its alloys, copper and its alloys, titanium and steels, including heat-resistant ones. Bars and pipes made of light and copper alloys are subjected to cold straightening. Editing of products from high-strength and heat-resistant alloys is carried out in a hot state.

Stretch straightening is subjected to rolled products made of aluminum alloys and low carbon steel, as well as sheets of special steel - stainless, high-strength, etc. This type of dressing is mainly used in the production of thin-sheet rolled products. Sheets up to 20 mm thick and more were also subjected to stretch straightening. Stretch straightening favorably affects the technological properties of sheets subjected to subsequent cold sheet stamping. With plastic stretching of sheets during the straightening process, structural changes in the metal caused by aging are removed.

Pressed rods and pipes are usually not only curved, but also twisted along the axis. To correct twisting, stretching straightening machines are equipped with spinning heads. Strongly twisted bars are untwisted before stretching on spinning machines with 2-3 spinning heads.

Straightening by stretching on stretching machines is carried out at a relative elongation of 1-3%. Since, in this case, stresses arise in the metal of the bars, somewhat exceeding the yield strength, the straightened metal is strengthened. Therefore, in order to strengthen the metal, stretching of not only pressed, but also rolled rods is increasingly being used. For hardening, the bars are stretched by 10–25%, as a result of which the strength and hardness of the metal sharply increase.

Straightening of hot-rolled bars on stretch straightening machines in a number of cases successfully replaces the broaching process on drawing mills for the purpose of calibration and hardening. Stretched straightened bars are obtained with the same diameter along the entire length and are strengthened. Before dressing, hot-rolled bars are not cleaned of scale, since the scale in the process of stretching lags behind the surface of the bars and is easily removed.

The stretching machine for cold straightening of bars and pipes is shown in fig. 5.13. It consists of a frame with two rectangular stepped columns 3, main hydraulic cylinder / for driving the front head 2, rear head 5 and metal loading and unloading mechanisms mounted on special trolleys 4.

front head 2 designed for clamping one end of the straightened product and stretching the product after straightening by torsion. Four pads are mounted in the head body, along which wedges with clamping jaws attached to them can move. The wedges are driven by four pneumatic cylinders attached to the body. With the help of these cylinders, the end of the bar or pipe is pre-clamped. When the product is stretched, the wedges self-tighten, providing the required clamping. The head moves along the rails of the bed on the rollers.

The rear unscrewing head 5 is designed to clamp the second end of the pipe or rod and turn it to the required angle. It can also move along the bed. The movement of the head is carried out from a separate drive. Fixing the head in a certain position on the frame is carried out using a special device consisting of four pneumatic cylinders and wedges that engage with rectangular grooves of the columns.

CHAPTER VI. WORKING AND CONTROL AND MEASURING TOOLS USED FOR EDIT

§ 1. GENERAL REQUIREMENTS FOR THE WORKING TOOL

Working tools for dressing, depending on the type of equipment used and technological process, are quite varied.

The main types of working tools are: rollers when straightening on roller straightening machines, rolls - on oblique-roll rotary straightening machines, dies - on mechanical crank and screw friction presses, screw presses with an arc drive, as well as on stamping hammers. When editing on forging hammers, the working tool is strikers, one of which is upper, the other is lower. When dressing on hydraulic and mechanical cranks correct presses prisms are most often used as a working tool. For stretching machines, clamping jaws are the working tool.

In addition to the main working tool, when editing, an auxiliary working tool is often needed: right hammers, linings, crowbars for tilting, various pliers, etc.

8.38.1 Before straightening, the plates are inspected and their initial flatness is measured.

8.38.2 On the surface of the plates, in order to avoid the formation of imprints during dressing, coarse lagging scale, exfoliated films and other impurities are not allowed. Cracks on the surface of the plates are not allowed. These defects must be removed before editing.

8.38.3 In the process of dressing, it is necessary to monitor the cleanliness of the surface of the plates; scale separated during dressing must be periodically swept away.

8.38.4 The boards are straightened using spacers with a thickness of 30 mm to 100 mm, a width of 100 mm to 200 mm, a length of 200 mm to 800 mm. Gaskets are made of carbon or low alloy steel with a hardness less than that of the metal being straightened. Gaskets should be even with parallel edges without nicks, cracks, sagging, burrs, the edges should be oval.

8.38.5 In the case of straightening curved sections with a bulge directed upwards, two spacers are installed on the press table parallel to its transverse axis and at an equal distance from it, with a distance between them of at least 1000 mm. The third gasket is installed from above, on the convex part of the plate parallel to the two lower ones.

In the case of straightening a curved section with a bulge directed downwards, one gasket is installed on the press table along its transverse axis, and two gaskets are installed on the plate parallel to the bottom and at an equal distance from it.

The displacement of the spacers from the specified position relative to the transverse axis of the table should not exceed 150 mm, and their distance from the longitudinal axis should not exceed 1500 mm.

When straightening, the plate is installed in such a way that two spacers are located along the boundaries of the curved section, and the third is in the center of the bulge.

8.38.6 The straightening of the curved section is carried out in one working move, during which the curved section of the slab is first brought to a flat state, and then reverse deflection is given to it. The value of the reverse deflection is set approximately in accordance with table 27 and should ensure that the required flatness of the slab is obtained.

Table 27

The values ​​of the reverse deflection indicated in Table 27 can be corrected during the straightening of the slabs, taking into account the nature of the flatness and other unaccounted for factors.

9 Delivery and shipment of metal

9.1 After obtaining satisfactory results of mechanical tests, the metal is delivered to the sheet-finishing area.

9.2 The metal accepted by the Quality Control Department workers on racks No. 57 and 59 is issued to the sheet finishing area.

Sorter-deliverer together with QCD controller check the side and end edges of the rolled products for the presence of unacceptable defects, check the data of the forming card and the compliance of the rolled products with ND and sign the forming card.

In the case of production of rolled products with deviations from the requirements of technology and ND, the decision to ship it is made by the Quality Director-Head of the QCD on the basis of a permit card, the form of which is given in Appendix E.

9.3 The issued formation card is sent for shipment and serves as the basis for issuing a certificate.

After receiving satisfactory test results, the mechanical test inspector enters all the information necessary for issuing a certificate into the formation card. Upon receipt of the results of mechanical tests for products for export purposes (yield strength, tensile strength and impact strength) at the lower values ​​provided for by the RD or customer requirements, repeated tests are carried out for this type. The results of the retests are final. After issuing the quality certificate, the control foreman of the QCD checks the compliance of the data of the forming card indicated in it and approves it, after which he transfers the forming card to the foreman of the sheet finishing department for shipment.

9.4 Shipment of metal from the warehouse to the wagons is carried out only after all documents are completed. Before shipment, the compliance of the documents with the actual presence of metal is checked.

Shipment of sheets and plates is made both on actual, and on theoretical weight.

The order of loading and fastening of rolled products - in accordance with the rules applicable to this type of transport.

Responsible for the formation of rolled products in batches and the registration of metal for delivery is the foreman of the formation.

Responsible for obtaining test reports - the foreman of the sampling site.

9.5 In the forming cards for sheets with a semi-edged or rolled edge, the actual and theoretical mass of the shipped metal is indicated. Shipment of metal is carried out according to the actual weight.

9.6 The main types and causes of defects in plate products and measures to eliminate them are given in Appendix G

4.36 /5 (87.27%) voted 11

Manual editing of sheet metal.

The dimensions of the plates are 1.5 X 1.5 m; 2.0 X 2.0 m; 1.5 X 3.0 m. As a rule, regular plates are cast from gray cast iron in ribbed or solid massive. The working surface of the stove must be flat. Sometimes such plates line the entire area of ​​\u200b\u200bthe correct room.

Plates are installed on wooden bars, with height working surface from the floor 400-650 mm. The main tools for straightening on the stove are hammers and sledgehammers.

Correct hammer handle. Hammer weight. Hammer weight.

The working surface or striker of these hammers and sledgehammers is flat or slightly convex, depending on the location and nature of the required impact. They are usually made with various surfaces at the ends - two-faced, as well as with an elongated and narrow striker. The weight of hand hammers - handbrakes ranges from 3/4 to 1 ½ - 2 kg. The weight of the sledgehammer ranges from 5 to 15 kg. Handles for hammers and sledgehammers are made of strong, solid wood- elm, dogwood, mountain ash, birch, etc., and are fixed in the nest with an iron wedge.

Hammer handle length.

Depending on the weight of the hammer or sledgehammer, the handle is given the appropriate length (Table 1).

Table 1. The length of the hammer handle depending on the weight.

The shape of hammers and sledgehammers.

The forms of hammers and sledgehammers are shown in fig. one.

Rice. 1. Hammer and sledgehammer.

Rice. 2. Ironers.

The trowels used for straightening have different shape; their samples are shown in fig. 2. Some trowels (2, a and e) are inserted with their shanks into the holes of a special handle, while the rest (2, b, c and d) are mounted on wooden handles like hammers.

For various profiles metal, trowels of various shapes are used.

Metal straightening technology.

It is impossible to give exact instructions on how to edit. Editing skills are acquired by experience. We can only note some basic editing techniques. The main technique for manual dressing of metal is the impact of a hammer or sledgehammer on the metal. For straightening metal, they mainly use the so-called shoulder blow, that is, such a blow, in which all the joints of the arm work: shoulder, elbow and carpal. This provides the impact with the necessary force. The force of the blow depends on the weight of the hammer and mainly on the speed at which it strikes. This speed depends on the magnitude of the swing and on the effort that is applied to move the hammer down.

High performance with the least fatigue of the body is achieved by a certain rhythm in work, i.e., for a certain time, you need to perform a certain number of working movements, using all means to eliminate unnecessary effort, for example, use the recoil force of the hammer from the metal when lifting it up to deliver the next blow . Equally important is the ability to choose the right place for striking, ensuring the straightening of the metal. There is a curvature of sheets in the form of one or more bulges in the middle of the sheet between its stretched edges or a stretched middle of the sheet with wavy edges.

Rice. 3. A sheet of metal with a bulge in the middle (a) and at the edge (6).

The numbers show the sequence of hammer blows.

The bulge indicates that at that location the surface area of ​​the metal is greater than the area over which the bulge has formed. To straighten such a bulge, it is necessary to direct the hammer blows not at it, but at the metal around it and in such a sequence as to gradually distribute the stretched places (Fig. 3, a). If, however, strikes are made on the bulge, then the metal under their influence will be distributed, and the bulge will increase. With several bulges on the surface of the sheet, blows are applied to the metal in the isthmuses between them, bringing all the bulges into one common one, and then the stretched surface of the metal is stretched by blows. With a wavy edge of the sheet (Fig. 3, b), blows are applied to the stretched part of the metal, the metal is stretched, and the waviness disappears.

The surface of the straightened sheet is checked with a metal ruler, which is applied with an edge to the sheet in various directions. The gap between the sheet and the ruler is measured with a feeler gauge.

Metal straightening method. Deposition of metal.

Sectioned metal is usually corrected by upsetting (fitting) and flexible, and only in rare cases is metal expansion (stretching) used.

It is edited by hand on a stove or on special anvils with cutouts (Fig. 4). On the sides of the cutout of the anvil, the metal is laid with the side opposite to that on which the blows will be struck.

Rice. 4. Anvil for manual dressing shaped metal:

1 - straightened metal; 2 - anvil with cutouts.

Sectioned metal with helical curvature is corrected in a cold state by twisting in reverse side lever devices (forks). With a significant curvature, the profiles are edited in a hot state

Tool for straightening metal. Screw yoke.

When straightening high-quality metal, various devices are used.

One type of such a device is a screw yoke (Fig. 5). The straightening process consists in the fact that a curved profile is installed in the body of the yoke, it is straightened by pressing the screw on the corner from the side of the bulge. Sectional metal straightening screw yoke flows slowly.

Rice. 5. Screw yoke:

1 - screw with tape thread; 2 - yoke body; 3 - straightened metal (corner).

When editing, pay special attention to stainless steels type 18-8. Due to the tendency to intergranular corrosion, it is forbidden to straighten sheets of this steel by hitting them with a steel sledgehammer. When editing, it is necessary to use either copper sledgehammers, or use copper trowels, or copper backing sheets. Plates before editing stainless steel sheets are thoroughly cleaned. Local heating with a gas burner is not permitted.

To Category:

Metal bending and straightening

Straightening of strip and sheet material

Edit strip material. The curved strip is placed on the slab and, holding it with the left hand, the right hand strikes with a hammer on the convex places, striking 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 strokes 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 is directed to the marked places gas burner, 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. 7. Editing curved shafts: a - screw press to straighten the shaft, b - checking the shaft in the centers with a fine

Almost everything begins with straightening metal " metal work". A happy exception is when you receive a completely new sheet or profile piece from stock.

Editing is subject to:

• steel sheets from non-ferrous metals and their alloys;
• steel strips;
• pipes;
• rod material and wire.

Metal welded structures are also subjected to straightening.

GOCMAKSAN STORM 1601 machine.

Definition of the term "metal straightening"

Editing of metal is an operation that consists in eliminating defects in parts and workpieces: curvature (bulge or concavity), irregularities (curvature, warping, etc.), etc. It consists in compressing a convex metal layer or expanding a concave one and is carried out the action of pressure on any part of the workpiece or workpiece.

Methods and methods of editing

There are two main methods of straightening any metals:

• manually. It is carried out with a hammer on anvils, steel right slabs etc.
• machine. Produced on straightening machines (presses or rollers).

The metal is ruled in a cold or heated state. The choice is determined by the amount of deflection and its size and the material of the workpiece.

When straightening metal great importance It has:

• the correct choice of the place on which to strike;
• comparison of the force of impact with the magnitude of the curvature of the metal. It should be reduced as you move from maximum to minimum bending.

With a large bend of the strip “on the edge”, blows should be applied with the toe of a hammer. This will lead to one-sided stretching (elongation) of the bend. The strips, which are a "twisted bend", are corrected in the direction of unwinding. The check is carried out on initial stage"by eye", and at the end - on surface plate or a curved ruler. Metal bars should be straightened on an anvil or plate from the edge to the middle.

Let's linger on the consideration of editing sheet metal, because this is the most difficult operation. A sheet of metal should be placed on the plate with the bulge up. We will strike with a hammer from the edge of the sheet towards its deformed part. Under the action of directed impacts, the flat part of the sheet will stretch, and the convex part will straighten. When editing sheets hardened metal should be applied frequent, but weak blows with the toe of the hammer in the direction from the concavity to its edges. In this case, the upper layers of the metal will be stretched, and the defect of the part will be eliminated.

Machine «GT-4-14».

Applied equipment and tools

The following equipment is used for straightening metal:

• correct plate;
• straightening grandmas.

As a tool, hammers are used, having round, radius or plug-in strikers made of soft metal. Thin sheet metal they rule with a wooden hammer (mallet).