RU2313415C1 - Drawing method with use of elastic fluid - Google Patents

Abstract

FIELD: plastic working of metal, namely drawing of flat blank by means of elastic fluid.

SUBSTANCE: drawing is performed by two transitions with use of elastic insert placed on bottom of die at first transition and removed before second transition. Insert in the form of spherical segment whose height is equal to depth of formed cavity is used.

EFFECT: improved quality of drawn parts due to uniform wall thickness.

2 dwg

Description

The invention relates to the field of metal forming, in particular to cold stamping, and more particularly to methods of drawing with elastic media, and can be used for the manufacture of parts from flat blanks.

Known methods of manufacturing parts by hood, in which the workpiece is pulled with an elastic punch into a rigid matrix [1].

Closest to the proposed technical solution is a method of stretching an elastic medium of hollow parts from sheet metal [2].

In this method, a flat preform is mounted on a rigid matrix and exposed to it with an elastic punch.

Known technical solution has the following disadvantages:

- a large thinning of the central zone of the workpiece and a pronounced unevenness of the wall thickness of the finished product, due to the fact that at the beginning of the drawing process this zone experiences significant stretching;

- uneven movement of the workpiece flange during shaping, leading to its one-sided tightening and, as a result, to the marriage of the product.

The claimed technical solution is aimed at improving the quality of manufacturing parts from sheet blanks, namely, to obtain hollow cylindrical parts with high uniformity of wall thickness.

This is achieved by the fact that in the method of stretching a flat blank with an elastic medium by an elastic punch into a rigid matrix using an elastic insert, according to the invention, the extraction is carried out in two transitions, and on the first of them, an elastic insert is installed on the bottom of the matrix to prevent excessive thinning of the molded part. The insert has the shape of a spherical segment, the height of which is equal to the depth of the cavity being formed.

Figure 1 presents a diagram of the preparation of an intermediate preform: to the left of the axis of symmetry - the initial position of the preform before drawing, to the right - obtaining an intermediate preform; figure 2 is a similar diagram of the finished part.

The method is as follows. At the first transition (Fig. 1), an elastic insert 2 in the form of a spherical segment is mounted on the bottom of the rigid matrix 1. Then, a flat blank 3 is placed on the mirror of the matrix 1. A press force is applied to the container 4, into which the elastic punch 5 is placed, and a hood is drawn to a depth equal to approximately 0.3 of the depth of the part being formed. Before the second transition (Fig. 2), the elastic insert 2 is removed from the matrix 1, a press force is applied to the container 4, and a final drawing is made.

The use of an additional transition in the proposed method of stretching an elastic medium leads to a redistribution of deformations and stresses in the bottom of the workpiece.

During deformation, the elastic liner blocks the central zone of the workpiece from excessive local thinning. Blocking is provided by friction forces on the contact surface of the liner and the workpiece resulting from its pressing against the liner by a deforming force from the side of the elastic punch. As the drawing depth increases, the magnitude of this pressure increases and, accordingly, the back pressure from the side of the elastic insert increases. Creating back pressure on the workpiece from the side of the liner allows you to increase the ductility of its material by imposing additional compressive stresses and creating a favorable stress state scheme and thereby creates the possibility of increasing the depth of drawing.

As a result of intensive blocking, the cross section, which is dangerous from the point of view of excessive thinning and possible destruction, is shifted from the center of the workpiece to the flange, that is, to a zone that is more hardened and has a greater wall thickness. In this case, the flow of the material is inhibited in the central zone and its flow is simultaneously intensified in sections adjacent to this zone.

When using the proposed method, a high uniformity of the wall thickness of the formed part is ensured, which leads to an increase in the quality of the finished product, and it becomes possible to achieve a greater drawing depth, which expands the technological capabilities of the process.

In addition, the elastic liner centers the workpiece during extraction, holding it from possible displacement relative to the elastic punch.

The method makes it possible to obtain a part with a small thickness difference, which increases its strength and rigidity. For the manufacture of parts, it is possible to use sheet metal of a smaller thickness, which ultimately leads to a decrease in the weight of the part.

Information sources

1. Isachenkov E.I. Stamping with rubber and liquid. - M.: Mechanical Engineering. 1967, p. 36-37, 164-166.

2. A.S. USSR 1202664, class B21D 22/10, 01/15/80, BI No. 2.

Claims (1)

A method for drawing a flat preform with an elastic medium by an elastic punch into a rigid matrix using an elastic insert, characterized in that the extraction is carried out in two transitions using an elastic insert installed on the bottom of the matrix at the first transition, and removing it before the second transition, using the insert in the shape of a spherical segment with a height equal to the depth of the cavity being formed.

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