RU2267373C2 - Method for forming, mainly shapes with w-like cross section - Google Patents

Abstract

FIELD: plastic working of metals.

SUBSTANCE: method comprises steps of preliminarily bending strip for forming radius portions between members of blank and finally bending strip by applying normal and tangential efforts to blank members. At preliminarily bending strip its central portion is bent and simultaneously concave cylindrical shape is imparted to members of strip central portion at maximum camber consisting 0.5 - 0.6 of initial thickness of strip. Final bending is realized after applying normal efforts to peripheral portions of blank for further straightening concave portions of blank.

EFFECT: enhanced quality of W-shaped parts due to elimination of thinning them in radius portions.

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Description

The invention relates to the processing of metals by pressure and can be used in various industries for the manufacture of sheet profiles.

A known method of manufacturing products from sheet blanks, in which they pre-bend the strip, forming a radius section between the elements of the workpiece, and then carry out its final bending by applying normal and tangential forces to the elements of the workpiece [1].

A disadvantage of the known technical solution is that it is necessary to carry out experimental debugging of the bending process to ensure a given accuracy.

The closest to the proposed invention in terms of technical nature and the achieved effect is a method for manufacturing predominantly W-shaped sections, in which the strip is pre-bent to form radius sections between the workpiece elements, and the central part of the workpiece is finally bent to the required size by applying normal and tangential forces to the elements of the workpiece [2].

The known solution allows to reduce the bending radius of the profiles, to reduce the springing of the bending material, however, the thinning that occurs in the radius sections does not provide the required quality of manufacturing parts.

The technical result achieved by using the present invention is to improve the manufacturing quality of W-shaped parts by eliminating the thinning of the material in the radius sections of the part.

The achievement of the specified technical result from the use of the developed invention is ensured by the fact that in the method for manufacturing profiles of predominantly W-shaped section, in which the strip is pre-bent to form radius sections between the workpiece elements, and then its final bend by applying normal and tangential forces to the workpiece elements It is proposed to accompany the preliminary bending with the bending of the central part of the strip while simultaneously giving the elements of the central part of the cylinder ndricheskoy concave shape, that the maximum deflection which is between 0.5 to 0.6 of the original thickness of the strip, and the final bend is made after application of normal forces to the peripheral portion of the preform, followed by straightening the concave central elements of the workpiece.

The essence of the developed technical solution is illustrated by the drawing, which shows the stages of manufacturing a flexible profile of a W-shaped section from a sheet stock:

- figure 1 shows the initial position of the workpiece before the preliminary flexible central part of the workpiece;

- figure 2 shows the position of the workpiece after preliminary bending the Central part of the workpiece;

- figure 3 shows the position of the workpiece before the preliminary flexible peripheral sections of the workpiece;

- figure 4 shows the position of the workpiece after preliminary bending of the peripheral sections of the workpiece;

- figure 5 shows the position of the workpiece before starting the final bending with straightening of the central sections of the workpiece;

- figure 6 shows the position of the workpiece after final bending with straightening of the central sections of the workpiece;

- Fig.7 shows a W-shaped workpiece after bending;

- Fig. 8 shows a W-shaped part after final bending.

The proposed method is carried out in devices that consist of the following main parts.

A central punch 1 is attached to the inner slider of the press (not shown), and peripheral punches 2 are attached to the external slider of the press 2. On the press table there is a bending matrix 3 with sidewalls attached to it 4. On the sidewalls 4, mounting frames 5 are fixed, with which a flat blank 6 is oriented in the plan both along and across the center line of the stamp.

The workpiece 6 at the bending stages according to figure 2-6 assigned position 7-11. The bending of a flat sheet blank 6 into a W-shaped part is carried out as follows.

After placing the flat sheet blank 6 in the mounting frame 5 in the stamp for pre-bending, the working stroke of the internal press slider down is turned on, moving it together with the central punch 1 leads to preliminary bending of the central part of the blank 6 to the position according to FIG. 2 during the closing of the punch 1 s the central part of the matrix 3. Due to the fact that the punch 1 has a concave shape of the working part, and the central part of the matrix 3 has a convex shape, the workpiece 7 acquires a concave shape. After that, a command is received to move down the outer slider of the press together with the peripheral punches 2, which provide bending of the peripheral part of the workpiece 9 (see figure 4). After preliminary bending, the workpiece 9 is installed in the stamp for final stamping (see figure 5). The final bending of the central concave sections of the workpiece 10 (see Fig. 5) is carried out after preliminary pressing the peripheral sections of the workpiece 10 with peripheral punches 2, moving the central punch 1 until it closes with the workpiece 11 and die 3. As a result, the working surfaces of the punch 1 and the central part matrices 3 in the stamp for final stamping are flat, the central walls of the workpiece 11 and three radius sections are compressed, when the central section of the workpiece 11 is straightened, over EFINITIONS material of the central portion of the billet, leading to a decrease in the outer radius curved portions to values close to zero. After the bending of the part 11, the central and peripheral punches 1 and 2 are returned to their highest position, the stamped part 11 is removed from the working area of the device.

Obviously, the preliminary stamping of the central part of the workpiece 9 should be such that during final bending with compression of the walls and the product and its radius sections according to Fig.6, the central part is straightened without loss of stability.

In this case, the maximum deflection of the concave cylindrical sections of the Central zone of the workpiece 5 should be in the range of 0.5-0.6 from the thickness of the workpiece 6, thereby reducing the radius of the radius sections and preventing loss of stability of the Central part of the workpiece.

An example implementation of the proposed method are flexible. For the manufacture of W-shaped sections from heat-resistant steel with a tensile strength σ _in = 80 kg / mm ² and a yield strength σ _S = 50 kg / mm ² , with the following product parameters: thickness S = 1.0 mm, bending radius r = 0.2 mm, with a height H = 50 mm and a width of 50 mm of four rectangular walls of the part, the calculation of the workpiece is carried out according to the cold stamping guides (for example [3], p.137). The maximum deflection of the central part of the workpiece, with preliminary stamping, is taken to be 0.5 × S = 0.5 × 1.0 = 0.5 mm.

Prebending the central force _of the punch P _ave. Determined from the radius create stresses in the portion of the preform and the walls of the product is not more than the yield stress, i.e.

The bending force R _p with editing the peripheral walls (according to / 3 /, p.145) in the process of preliminary bending is calculated by the formula:

After preliminary bending, the part has a W-shape with concave cylindrical walls of the central section of the workpiece. The maximum deflection of the walls of the central section is 0.5 mm.

The final bending of the workpiece 10 (see figure 5) is carried out after installing the workpiece in the stamp for final bending. The peripheral sections of the workpiece are pressed by 10 peripheral punches 2 with a force of R _o.p. , which is taken equal to the effort of preliminary bending of peripheral sections and which is equal to 11 tns.

The movement of the Central punch 1 to close with the workpiece 11 and the matrix 3 leads to the straightening of the concave cylindrical sections, the maximum deflection of which is 0.5 mm. Effort on the central punch R _o.ts. determined by:

Thus, for the manufacture of profiles of a W-shaped section, techniques have been developed and the power parameters of the implementation of the presented technical solution have been established.

Information sources

1. Copyright certificate No. 657888 (USSR) M. Kl. B 21 D 5/00 "Method for the production of profiles". BI No. 15, 1979.

2. Patent RU No. 2110348 B 21 D 5/00, 22/02 "Method for the manufacture of predominantly W-shaped sections," Bull. No. 13, 1998

3. Malov A.N. Cold stamping technology. M.: Mechanical Engineering, 1969, p. 145.

Claims (1)

A method of manufacturing predominantly W-shaped sections, including preliminary bending of the strip with the formation of radius sections between the elements of the workpiece and its final bending by applying normal and tangential forces to the elements of the workpiece, characterized in that to improve the quality of the parts, preliminary bending is accompanied by bending of the central part of the strip with at the same time giving the elements of the central part cylindrical concave shapes, the maximum deflection of which is in the range from 0.5 to 0.6 a strip thickness, and the final bend is performed after the application of normal forces to the peripheral portion of the preform, followed by straightening the concave portions preform elements.

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