Draw Forming Method and Device

Abstract

A draw forming method for drawing a blank material (15). In this method, a restraint region (98) that is an outer peripheral section (21) of the blank material is held by a first holder means (22), and then a tension region (97) inside the outer peripheral section is displaced upward by a second holder means (23) relative to the restraint region. The displacement applies tensile force to a drawing region (96) that is the central section of the blank material.

Description

TECHNICAL FIELD[0001]The present invention relates to a draw forming method and device for reducing deflection created in the center of a blank material when the blank material is subjected to plastic working using a press and a metal die unit.BACKGROUND ART[0002]Japanese Utility Model Laid-Open Publication No. H01-153820, for example, proposes a draw forming method in which the periphery of a blank material is held by pressure from a blank holder, and the blank material is formed when subjected to plastic working using a metal die unit mounted on a press. This draw forming is described below with reference to FIGS. 13A through 13C hereof.[0003]In a forming method that uses a conventional drawing die 301, the periphery of a blank material B is first pressed by an upper die holddown 303 of an upper die 302 and a lower die holddown 305 of a lower die 304, and a section adjacent to the center of the blank material B is pressed by a pad 306 and a cushion 307, as shown in FIG. 13A.[0004]...

AI Technical Summary

Benefits of technology

[0010]Thus, the restraint region of the blank material is restrained by the first holder means, and the stretching region of the blank material is then displaced in the shearing direction by the second holder means, whereupon tensile force is applied to the stretching region of the blank material and the drawing region in the middle, and the deflection formed in the drawing region is removed. It is therefore possible to reduce deflection in the middle of the blank material set into the metal die unit.

[0012]In the thus-arranged device, the press operates the first holder means, the outer peripheral section of the blank material is restrained by the first holder means, and the press is then lowered further. The second holder means positioned on the inside of the first holder means then stretches the middle of the blank material outward. As a result, the deflection in the central section of the blank material is extremely small, and it is possible to reduce nonuniformities in the positional relationship between the central section and the upper and lower dies. It is therefore possible to reduce nonuniformities in the dimensions of the formed article when drawing is performed.

[0013]Preferably, in the device of the present invention, the press is a double-action press; the first restraining position is the position in which the first holder means protrudes past the second holder means and in which the blank material is held by the lowering of the double-action press; the second restraining position is the position in which the double-action press is lowered further from the first restraining position; the upper die is held to be capable of sliding in relation to the second holder means, and is disposed separate from an inner slider of the double-action press; and the first holder means and second holder means are fixed to an external slider positioned on the outside of the inner slider. As a result, tensile force is applied to the inside of the outer peripheral section and to the central section of the blank material until the blank material reaches the second restraining position while the outer peripheral section is restrained at the first restraining position, and deflection in the central section of the blank material can be prevented from occurring.

Problems solved by technology

As a result, there is concern that the forming dimensions will be markedly nonuniform.

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