SU1214278A1 - Die for beading parts from sheet work - Google Patents

Description

 ,

The invention relates to metal forming and die tooling.

The purpose of the invention is to improve quality by preventing loss of stability of the bead, local buckling and springback.

In Fig.1 schematically depicts a stamp, a general view; Fig. 2 shows the same in the extreme upper and extreme lower positions of the press ram.

The stamp contains a punch 1, mounted on the upper movable plate 2 matrix 3, fixed on the lower fixed plate 4, the clamp 5, working from a press buffer device (not shown),

The working surface 6 of the punch 1 has the shape and dimensions of the inner spherical surface of the part. The working spherical surface 7 of the matrix 3 is designed so that its center 0 is displaced upward relative to the center Oy of the working surface 6 of the punch 1 by the value

A (EL, - Rj (1-ClGt),

where K 0.7 - 0.9 is the coefficient, take into account 1 st (the mechanical characteristics of the metal, the tolerance on the sheet thickness and the value of the forced thinning of the metal; R is the radius of the working spherical

matrix surfaces; Rf, is the radius of the working spherical

punch surface; m is the flanging factor.

If the center of the spherical surface 7 of the matrix 3 is displaced upward relative to the center of the spherical surface 6 of the punch I by an amount smaller than A, then the gap between the working surfaces of the matrix 3 and the punch 1 in each section perpendicular to the surface of the matrix 3 is greater than the thickness of the bead. In connection with this, the workpiece is deformed under the conditions of a compressed-stretched stress state. In such a stress state pattern, metal breaks may form along the edges of the board, and the phenomenon of local buckling, local buckling of the board, reducing processing quality.

If the center of the spherical surface 7 of the matrix 3 is shifted upwards, U278 1

of the center of the spherical surface 6 of the punch 1 by an amount greater than A, then excessive overpressing and even cutting of the workpiece 5 takes place, which leads to a sharp increase in the deformation force and destruction of the matrix 3.

Smaller values of the coefficient K in the formula for determining A correspond to large negative and smaller plus deviations of the actual sheet thickness from the nominal one.

The physical meaning of the coefficient k is that it regulates the value of the compressed air pressure in the source of plastic deformation depending on the mechanical characteristics of the metal and the maximum deviations of the sheet thickness from the nominal one.

Ep l

The larger value (b &

. g metal yield strength, kg / mm;

dg is the temporary resistance of the metal, 25 kg / MMj, i.e. the more prone the metal to plastic deformation without destruction, the greater the magnitude of the coefficient K m can be accepted and, therefore, the height-varying gap between the matrix and the punch will be larger, and the magnitude of the compressive stresses in the plastic deformation zone will decrease. The required warping force is also reduced.

g The smaller the value of -t-, i.e.

Oh

thirty

the less prone the metal to plastic deformation without destruction, the smaller the value of the coefficient k can be accepted, the greater the value of A will need to shift the center of the spherical surface of the matrix relative to the center of the spherical surface of the punch. The larger value A of the displacement of the centers causes a smaller value of the variable height of the gap between the working surfaces of the die and the punch, which leads to a more rigid scheme of comprehensive volumetric compression, i.e. to an increase in the magnitude of the compressive stresses in the center of plastic deformation. The matrix 3 has a mirror of 8, and the punch 1 is made with a safety gear 9 attached to its end. The stamp also contains a blank 10 finished part I1.

The stamp works as follows.

Pre-cut into the combined stamp of a sheet with a thickness of 2.5 mm, a billet 10 with a diameter of 1–20 mm and a punched hole with a diameter of 45 mm is mounted on the mirror 8 of the matrix 3 and fixed along stops (not shown) along the outer contour. During the course of the slide (the press is not shown down by the safety gear 9 fixed on the end face of the punch 1, the workpiece 10 is additionally centered so that the axis of the hole exactly coincides with the axis of the punch 1.

The blank 10 is pressed against the mirror 8 of the matrix 3 by the clamp 5. The clamping force is selected from the condition that the flange of the part is not bent in the process of deforming the blank and is equal to 45 kN (4.5 tons |.

During the working stroke of the press ram, the upper plate 2 of the stamp moves down and the punch 1 draws in a part of the workpiece 10, adjacent to the central hole, into the working cavity of the matrix 3 and forms a bead with an internal spherical surface.

Due to the fact that the center Oj of the working spherical surface 7 matjf

X / XXX / XX

12U278

3 is displaced upward relative to the center 02 of the working spherical surface 6 of the punch 1 by the value A 0.7 mm, the gap between the workers, surfaces 5 and 7 of the matrix 3 and the punch 1 varies in height from 2.31 mm (the thickness of the metal with

 minus tolerance) to 1.8 mm.

So in each section,

10, which is perpendicular to the working surface of the die, the gap between the working surfaces of the die and the punch is smaller than the thickness of the bead. The metal is squeezed into the gap between the surfaces of the matrix and the punch under conditions of volumetric all-round compression. Due to this, the shape and dimensions of the inner spherical surface of the part are not distorted;

20 required precision sphere. The degree of roughness of the inner surface of the bead is determined by the roughness of the working surface of the punch. Local squeezing of the bead is excluded.

25 the degree of deformation smoothly increases along the height of the bead to its lower part. All this leads to an increase in quality due to an increase in the accuracy of processing.

 X XX X XX

X XXX y

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VNIIPI Order 824/15 Circulation 783 Subscription Branch PSh1 Patent, Uzhgorod, ul. Project, 4

Claims (1)

STAMP FOR DECORATING PARTS FROM SHEET Billets, comprising a lower plate with a matrix rigidly fixed on it and an upper plate on which a clamp and punch are mounted coaxially with each other with a working surface defined by radius, characterized in that, in order to improve quality by to prevent loss of stability of the side, local buckling and springing, the working surface of the matrix is outlined along the radius, with the centers of radii located on one straight line, and the center of the matrix is shifted relative to the center of the punch towards pu Anson. FIG. 1 SU, ·, 1214278 ¹ 1214278 ^