RU2446903C2 - Method of punching holes in thick-sheet material - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to metal forming. Method comprises creating cubic non-uniform compression stress in material separation zone and shift of separated parts relative to each other. Said cubic non-uniform compression stress in material separation zone is created by reverse extrusion of future waste material into face cavities of opposed male moulds and applying compression load on opposite edge zones of the part future holes.

EFFECT: higher efficiency and quality.

4 cl, 4 dwg

Description

The present invention relates to the field of metal forming, and in particular to methods of punching holes in sheet materials.

A known method of manufacturing holes in sheet materials by punching a workpiece with a rigid punch on a rigid matrix, between which there is a gap equidistant to the contour of the punched hole. (Romanovsky V.P. Handbook of cold stamping. - 6th ed., Rev. And add. - L.: Mechanical engineering. Leningrad. Department, 1979. p. 11 ... 12). The disadvantage of this method is the formation in the separation zone of the weight of the material of the workpiece from the punch and the burr from the matrix. In addition, the formation of cleavage cracks during separation of the material, directed towards each other from the side of the punch and matrix, leads to a reduced quality of the punched hole both in terms of the purity of the separation surface and its geometrical characteristics.

There is also known a method of punching holes in a plate material, which consists in applying on opposite sides of a sheet blank, in the area of the future hole, annular coaxially arranged stress concentrators, performed, for example, by machining in the form of annular grooves, and subsequent shearing of the material limited by the concentrators relative to the rest material. (Khtayk S.V. Finishing punching of plate material with preliminary creation of stress concentrators. Forging and stamping. - 2008. - No. 2, as well as Khtayk San Vin. Study of the process of finishing punching of plate blanks in the manufacture of aircraft parts. Abstract of dissertation for competition degree of candidate of technical sciences. M: MATI, 2008.).

The disadvantage of this method is the high complexity caused by the need for initial machining by cutting coaxially located stress concentrators before punching the hole.

The invention solves the problem of reducing the complexity and improving quality when punching holes in plate blanks.

To achieve the named technical result in the proposed method of punching holes in the plate material in the separation zone of the material create a three-dimensional diagram of the uneven stress state of compression with the subsequent shift of the separated parts relative to each other.

New in the invention is that the volumetric non-uniform stress state of compression in the material separation zone is created by reverse extrusion of the material of future waste into the end cavities of oppositely located punches and the application of a compressive load to the oppositely located near-edge zones of the future hole of the part, while the reverse extrusion of the material of the future waste is performed in the opposite direction the movement of the punches, and the shift of departure - by the associated movement of the punches or one of the punches, without applying to loads to the second punch, and compressive loads imposed on opposite sides of the plate material are applied to the annular sections of the part in the form of a uniformly distributed load, while the smaller diameter of the annular section is equal to the diameter of the hole being cut.

The accompanying drawings depict the following.

Figure 1. The initial position of the working elements of the stamp before implementing the method of punching holes in a plate material.

Figure 2. The first step in the implementation of the method is the creation of a volumetric stress state of compression in the zone of future separation of the material by reverse extrusion of the material of the future waste into the end cavities of the punches.

Figure 3. The second step in the implementation of the method is punching a hole by shifting the waste relative to the base material.

Figure 4. An embodiment of the method: punching a hole with one of the punches.

The proposed method is implemented as follows.

Plate blank 1 (figure 1), in which you want to punch a hole, is installed in a stamp that includes clamps 2 and 3, punches 4 and 5 at the ends of which open cavities 6 and 7 are made.

At the first stage of punching holes in the workpiece 1 to the clamps 2 and 3 (figure 2) apply force Q, developing in the contact zone with the workpiece 1 pressure is less than the yield strength of the workpiece material. Then the forces P are applied to the punches 4 and 5, moving them towards each other with a speed V. The forces P are then sufficient for plastic deformation of the workpiece 1 material under the action of the annular ends of the punches 4 and 5. At this stage, the punches moving towards each other 4 and 5 carry out the process of backward extrusion of the material of the workpiece 1 in the cavity of the punches 6 and 7. In this case, the forces Q applied to the clamps 2 and 3 have a value prohibiting the movement of the clamps 2 and 3 from each other under the action of plastically deformable metal blanks.

The punch 5, having introduced into the material of the workpiece 1 by a certain amount, stops the oncoming movement towards the punch 4 and begins to forcefully move in the opposite direction with a speed V equal to the speed of movement of the punch 4 (figure 3). When this occurs, the shift of the material 8 of the workpiece located between the annular ends of the punches 4 and 5, relative to the main material of the workpiece located between the clamps 2 and 3.

When implementing the proposed method, before the stage of shear of the material in the zone of its future separation, a volumetric stress state of compression is created, which prevents the formation of cracks and increases the ductility of the metal in the shear zone.

In another embodiment, at the shear stage, the force P (FIG. 3) applied to the punch 5 can be reduced to zero. In this case, the shear step can be performed without the participation of the punch 5 (Fig. 4), which, before the shear step is performed, is removed from the workpiece 1.

Both options for the implementation of the method can eliminate the formation of sagging material of the workpiece from the punches and provide punching holes without burrs.

The use of a particular hole punching option is determined by the plastic properties of the workpiece material and the required quality of the hole being punched. In this case, the first variant of the method is expediently used to obtain holes of higher quality in materials with little plastic under ordinary conditions.

It should be noted that the considered variants of the method can also be implemented when punching holes in plate materials in a heated state.

The proposed method of punching holes in plate materials can reduce the complexity and improve the quality of punched holes.

Claims (4)

1. A method of punching holes in a plate material, comprising creating a volumetric uneven compressive stress state in the material separation zone followed by a shift of the parts to be separated relative to each other, characterized in that the volumetric uneven compressive stress state in the material separation zone is created by reverse extrusion of future waste material into the end cavities of oppositely located punches and imposing a compressive load on oppositely located near-edge zones of the future its holes details. 2. The method according to claim 1, characterized in that the reverse extrusion of the material of the future waste is performed by the oncoming movement of the punches, and the shift of the waste - by the associated movement of the punches. 3. The method according to claim 1, characterized in that the shift of the waste is carried out by one of the punches, without applying a load to the second puncheon. 4. The method according to claim 1, characterized in that the compressive loads imposed on the opposite sides of the plate material are applied to the annular sections of the part in the form of a uniformly distributed load, the smaller diameter of the annular sections being equal to the diameter of the hole being cut.

Images