RU78709U1 - DEVICE FOR FORMING THIN-WALL TRUNKED SHRINKING SHELLS - Google Patents

Abstract

1. A device for forming thin-walled truncated tapering shells containing a punch, clamp, ejector, die, backing plate, characterized in that it is equipped with a stamp plate on which the container is mounted, inside of it on the stamp plate there is an elastic element located on the backing plate, between the die plate and the underlay plate have an elastic buffer. 2. A device for forming thin-walled truncated tapering shells according to claim 1, characterized in that the elastic element is made in the form of a ring of rectangular section with a part cut off from the side of the punch in the form of a conical section, the large diameter of which is equal to the inner diameter of the matrix and the smaller diameter is equal to the diameter of the ejector, and a height equal to the distance from the bottom surface of the matrix to the ejector point closest to the matrix in the initial position.

Description

The utility model relates to cold sheet stamping, in particular to the shaping of thin-walled axisymmetric shells, and can be used in the manufacture of large-sized thin-walled parts of a tapering shape on double-acting presses.

A known design of a device for shaping thin-walled tapering shells from a hollow conical billet by distributing and stretching it while holding the billet by the flange from the side of the large open end (Isachenkov E.I., stamping with rubber and liquid. M .: Mechanical Engineering, 1967, Fig. 171a).

The disadvantage of this device is that it does not provide high accuracy of the contours of the finished part as a result of uneven elastic springing along the length of the generatrix.

The closest in technical essence to the claimed, which is taken as a prototype, is a device for distribution with stretching of a hollow conical billet, consisting of a punch for distribution, matrix, clamp, ejector and container (USSR AS No. 1748905 IPC B21D 22/30 publ. 23.07. 1992, Bull. No. 27). As a result of the fact that after the distribution of the conical billet, its smaller end is clamped by the tool and the workpiece is additionally stretched in the axial direction, the accuracy of the contours of the stamped part is significantly increased.

A disadvantage of the known device is that during the final stretching of the preform, uneven thinning of the preform occurs along its generatrix. Blank elements,

adjacent to a larger end, have a large cross-sectional area. The axial tensile stresses in these elements are smaller and the workpiece is thinned less. When moving to a smaller end face, the cross-sectional area of the workpiece decreases (sometimes by 2–3 times), which leads to an increase in tensile stresses and to more intense thinning of the workpiece. As a result of this, in stamped parts, in the area of the smaller base, the wall thickness decreases, which necessitates the use of a thicker billet and leads to overuse of the stamped metal.

The utility model is based on the task of improving the quality of workpieces and obtaining parts with constant and variable thickness.

The solution to this problem is achieved by the fact that the device for forming thin-walled truncated tapering shells containing a punch, a container, a clamp, an ejector, a matrix, according to a utility model, is equipped with a stamp plate on which the container is mounted, an elastic element located on it the underlay plate, between the die plate and the underlay plate there is an elastic buffer.

The elastic element is made in the form of a ring of rectangular cross section with a part cut off from the side of the punch in the form of a conical section, the larger diameter of which is equal to the inner diameter of the matrix, and the smaller diameter is equal to the diameter of the ejector and a height equal to the distance from the bottom surface of the matrix to the ejector point closest to the matrix in the original position, in addition between the backing plate and the bottom plate of the stamp is made additional elastic annular element of rectangular cross section with a height equal to the distance from the plate die to the underlay plate, the outer diameter is less than the inner diameter of the container, and the inner diameter is larger than the diameter of the ejector. The elastic element may be solid or composite.

Figure 1 shows a stamp for shaping convex thin-walled tapering shells (to the left of the axis in the open, and to the right of the axis in the closed position). Figure 2 shows a stamp for shaping concave thin-walled tapering shells (to the left of the axis in the open, and to the right of the axis in the closed position).

The device consists of a stamp plate 1 on which the container 2 is installed. Inside the container there is an elastic buffer 3 mounted on the stamp plate 1, a backing plate 4, an elastic element 5. An elastic buffer 3 is installed on the stamp plate 1, and a lining plate is placed on top of it 4 and the elastic element 5 is placed on the backing plate 4. The punch 6 and the ejector 7 move inside the container, clamping the smaller diameter of the conical truncated workpiece 8. On top of the container, a matrix 9 is installed, to which the clip 10 is pressed hnyaya frustoconical portion 8. The workpiece pressing force 10 is transmitted via pin 11.

The device operates as follows:

The conical truncated workpiece 8 is installed by the outer surfaces adjacent to the end face of the larger base to the matrix 9, and adjacent to the end of the smaller base to the ejector 7. Then the workpiece is clamped on the inner surfaces of the matrix 9 with a clamp 10, and to the ejector 7 by the punch 6. Tool, where the workpiece is clamped, it is made with work surfaces having a taper matching the taper of the workpiece. During movement, the force acts on the punch, equal to the total force created by the ejector and the force from the pressure of the elastic element 5. Since the elastic element is in a closed volume, the internal pressure in it depends on the possible movement of the backing plate 4, which creates a compressive strength buffer 3 in the form of a ring. In this case, the punch, introducing into the elastic element 5, moves part of the volume V ₁ (displaced volume) to

volume V ₂ . Since the elastic element is practically incompressible, we can take V ₁ = V ₂ . The volume V ₁ , the cross section of which has a figure close to the triangle Δabc, is limited on the one hand by the outer surface of the part and, on the other, by the inner surface of the elastic element. The volume V ₂ has in cross section the shape of the rectangle a'b'c'd 'and is equal to:

where D _k , d ₆ - respectively, the diameters of the container and the ejector,

Δh is the height of the displaced displaced volume.

The volume of the displaced part of the elastic filler:

Volume of a large truncated cone:

Cylinder volume:

Small truncated cone volume:

D _in , d _in - respectively, the diameter of the upper clip and the diameter of the 2 ejector.

H is the height of the part.

h ₀ - the height of the truncated cone.

In the case of consideration not of a truncated cone, but details of complex shape

V _{bk is} calculated by the formula:

where ρ = f (h) is the given function of the dependence of the radius of the outer surface of the part on height.

From the equality condition for formulas (1) and (3) we find

The amount of movement of the underlay plate is equal to the amount of compression of the elastic buffer 2. Knowing the required pressure and the value of the active tangential stresses τ on the contact surface of the workpiece with the punch, which are found from the solution to the problem of a possible break or condition of a given distribution of the thickness of the part. Find the force acting on the backing plate, taking into account that the pressure of the elastic filler in a closed volume is distributed equally in all directions. From the condition of equal efforts, both from the side of the elastic filler and from the side of the elastic buffer, we have

where q _e , q _b - respectively, the pressure of the elastic filler and the elastic buffer,

D _b = (0.75-0.8) D _k - the outer diameter of the elastic buffer,

d _b = (0.75-0.8) d _c is the inner diameter of the elastic buffer.

These ratios of diameters are taken so that when compressing the elastic buffer up to 30% there is free space between the backing plate 4, the stamp plate 1, the container 3 and the ejector 6. This eliminates the rapid wear of the elastic buffer and prevents damage to the container at high pressures, in the case of errors when adjusting the stroke of the punch. From expression (6) we find

By nomogram (V.P.Romanovsky. Handbook of cold forming. L .: Mechanical Engineering 1971, 644-645 p.) With the determined value q _b are geometrical relationships used for the elastic buffer material, namely, , (where h _b is the height of the elastic buffer), as well as the amount of compression deformation of the elastic buffer The value of compression deformation makes it possible to determine the height of the elastic buffer, taking into account the dependence of 5:

The last expression allows you to find the difference in diameters:

or

The diameter of the ejector is determined by the geometry of the part and the grip length (10-15) of the thicknesses, then the diameter of the container is:

Using the device of the proposed design allows to form thin-walled truncated tapering shells with large deviations of the diameters of the large base to smaller and receive parts by adjusting the pressure of the workpiece on the punch using an elastic element, to obtain the thickness of the part with a different nature of its change along the generatrix (constant thickness, variable as increasing to larger base from a smaller base, and decreasing).

Claims (2)

1. A device for forming thin-walled truncated tapering shells containing a punch, clamp, ejector, die, backing plate, characterized in that it is equipped with a stamp plate on which the container is mounted, inside of it on the stamp plate there is an elastic element located on the backing plate, between an elastic buffer is located by a stamp plate and a bed plate. 2. The device for forming thin-walled truncated tapering shells according to claim 1, characterized in that the elastic element is made in the form of a ring of rectangular section with a part cut off from the side of the punch in the form of a conical section, the larger diameter of which is equal to the inner diameter of the matrix and the smaller diameter is equal to the diameter the ejector, and a height equal to the distance from the bottom surface of the matrix to the nearest point from the matrix of the ejector in the initial position.