Shearing method

Abstract

The present invention provides a shearing processing method. For a workpiece obtained by welding a steel plate with a large step width at the welded portion and / or with a strength of 1000 MPa or more and other steel plates, the shearing line crossing the welded portion is In the shearing process in which the shearing process is performed, a sheared surface with less residual stress and excellent surface properties is formed, and the life of the punch is prolonged. The shearing method of the present invention is to use a punch and a die to shear a workpiece having a welded portion, wherein two protrusions are provided on the tip of the punch, and the two protrusions are clamped from both sides. Hold all or part of the welded part of the workpiece, and shear the workpiece along the cutting line intersecting the welded part.

Description

technical field [0001] The present invention relates to iron, copper, zinc, tin, aluminum, titanium, magnesium, or alloys based on these used in automobiles, home appliances, building structures, ships, bridges, construction machinery, various factories, etc. A method of shearing a metal plate, and particularly relates to a method of shearing capable of improving fatigue properties and hydrogen embrittlement resistance in a sheared surface of welded metal plates. Background technique [0002] Shearing processes such as blanking and punching of metal sheets based on stamping are widely used in the processing of electronic equipment and automotive parts due to their high productivity and low processing costs. However, when a high-strength steel sheet exceeding 1000 MPa is subjected to shear processing, the tensile residual stress (hereinafter, unless specifically denied, the tensile residual stress is simply described as "residual residual stress) in the punched end surface (s...

AI Technical Summary

Problems solved by technology

However, the sheared surface formed by the method of Patent Document 1 has difficulties

That is, when the shape of the punch is made uniform in the direction of the cutting ridge line, there is a problem that fractures are likely to occur in the welded part with low ductility and toughness in the above-mentioned sheared surface.

[0012] When the shear processing conditions are controlled in such a way that the residual stress of the welded part is preferentially reduced, the fatigue resistance and hydrogen embrittlement resistance can be further improved in the shear processed surface of the workpiece, but when as shown in the non-patent literature 1, when the thickness ratio between the gap between the punch and the die and the thickness of the workpiece is 1% or less, due to the slight offset of the punch, there is contact between the punch and the die, and the punch and / or or the risk of die breakage

[0013] In addition, when the thickness ratio between the gap between the punch and the die and the thickness of the workpiece is 1% or less, the side of the punch and / or the die is worn and the gap changes, and in the sheared surface of the workpiece, there is The problem that the effect of improving fatigue resistance and hydrogen embrittlement resistance cannot be sufficiently obtained

[0014] In addition, the punching method of Patent Document 2, the press forming method of Patent Document 3, and the trimming device of Patent Document 4 do not disclose shearing in which shearing is performed along a shearing line intersecting a welded part.

That is, none of Patent Documents 1 to 3 discloses the conditions for reducing the residual stress on the sheared surface of the welded portion.

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