RU2078634C1 - U-shaped bending stamp - Google Patents

Abstract

FIELD: plastic working of metals. SUBSTANCE: stamp has punch with side undercuttings, matrix unit with bending device provided with two immovable halves of matrices, which are mounted with adjustable gap relative to punch, and pressure device mounted in axial opening of matrix unit. Each matrix half is positioned in spaced relation to punch, with size of space Z being at least equal to 1.57/3R+1.5S/-R, where Z is space between matrix half and punch, mm; S is billet thickness, mm; R is punch rounded edge radius, mm. EFFECT: increased efficiency, simplified construction and enhanced reliability in operation. 1 dwg

Description

 The invention relates to the field of metal forming and can be used when bending U-shaped parts, taking into account the unstable springing of the workpieces.

 Known dies for bending sheet blanks containing a punch, matrix and bending device in the form of movable crackers [1] The disadvantage of such dies is the relatively high manufacturing costs due to the complexity of the design of the bending device.

 A bending stamp is known, comprising a punch with undercuts on the sides and a matrix assembly including bending inserts mounted on two levels with the possibility of adjusting the gap relative to the punch, the upper inserts being fixed with a gap greater than the thickness of the workpiece, and the lower inserts with a gap less than the thickness of the workpiece [2] Pulling the bent workpiece by the punch through the inserts causes it to thin and additional bend to compensate for springing. The disadvantages of this stamp are the weakening of parts in places of thinning, an increase in the stamping force and wear of the stamp due to pulling the workpiece into the gap less than its thickness.

 The technical problem that the invention solves is the reduction of the cost of manufacturing a stamp, improving the quality of parts, reducing the stamping force and wear of the stamp by simplifying the design of the bending device and increasing the gap between the half-matrix and the punch.

 This goal is achieved by the fact that in a stamp containing a punch with lateral undercuts and a matrix unit with a bending device, the bending device is made in the form of two additional (upper) fixed half-matrices with an adjustable clearance relative to the punch, approximately equal to 3.5 times the scan length of the radius part Details the gap between the lower half-matrix and the punch is not less than the thickness of the workpiece.

 The drawing shows the details of the stamp at the beginning of the bending process and at the end (right). The stamp contains a punch 1 with undercuts of the sides and edges rounded by a radius R; a matrix unit with a bending device in the form of upper half-matrices 2 with the possibility of adjusting their gap Z relative to the punch; the lower half-matrix 3 and the movable clip 4 are also installed in the matrix block.

The stamp works as follows. The workpiece is stacked on the upper half-matrix 2 and clamp 4. When the punch 1 moves down, it moves the workpiece together with the clamp and freely bends the workpiece in the gap Z, to which the position of the upper half-matrixes is adjusted 2. During the further course of the punch, the workpiece is pulled into the lower half-matrix 3, one-sided the gap with respect to the punch is not less than the thickness of the workpiece S. On the edges of the punch rounded with radius R, the radius parts of the part are formed from sections of the workpiece that have previously received free plastic bending. If the length of such a section L exceeds the scan length of the radius of the part 1.57 (R + 0.5S), then after pulling the workpiece into the lower half-matrix, the excess l represents the bend of the workpiece by an angle exceeding 90 ^o . By adjusting the clearance Z, we obtain the required bend angle.

 Adding to the design of the stamp additional half-matrices 2, which perform the function of a bending device, is associated with lower costs than the use of movable bending devices, driven by wedges and levers. The bend of the workpiece compensates for its springing, despite the fact that the gaps between the lower half-matrix and the punch into which the workpiece is drawn can exceed S by the tolerance on the thickness of the workpiece plus the contribution of the stamp. In any case, when pulling the workpiece, its thinning is excluded, as well as the increase in stamping force and stamp wear associated with it.

To design a stamp, it is necessary to evaluate the range of adjustment of the gap between the upper half-matrix and the punch. The bending moment in the workpiece at the edge of the punch chase in terms of at least σ _{s S} ^2/4 (not taken into account the increase of yield stress σ _s, induced hardening). The direction of the upper edge of the jaws and torque decreases at the boundary elastic and plastic bending portions is σ _{s S} ^2/6, i.e., 1.5 times less than on the edge of the punch. Therefore, the total length of these sections should be 3 times the scan length of the radius part of the part 1.57 (R + 0.5S). The maximum clearance Z between the upper half-matrix 2 and the punch 1, provided by the adjustment, should be 1.57 (3R + 1.5S) R.

 Thus, the proposed design can improve the quality of parts obtained by a U-shaped flexible, and reduce the cost of manufacturing dies.

Claims (1)

A stamp for the U-shaped bending comprising a punch with lateral undercuts, a matrix unit with a bending device made in the form of two stationary half-matrixes, installed with an adjustable clearance relative to the punch, and also a clamp installed in the axial hole of the matrix block, characterized in that each half-matrix is installed relative to the punch with a gap
Z ≅ 1.57 • (3R + 1.5S) R,
where S is the thickness of the workpiece, mm;
R is the radius of rounding of the edges of the punch, mm