Drawing die

Abstract

The invention provides a drawing die, which can be used for effectively controlling the spring-back problem by increasing blank holder force within a small-stroke range before complete drawing. The drawing die comprises a molding die and a blank pressing die, wherein the molding die comprises an upper die which is arranged on an upper die holder and a lower die which is arranged on a lower die holder; a channel is formed in a lower blank pressing die; a force increasing mechanism which is in slide fit with the channel is arranged in the channel, and the sliding direction is a vertical direction; the force increasing mechanism supplies upward lifting force to the lower blank pressing die to lock a workpiece to be machined at a delta stroke before complete drawing. In the scheme, the force increasing mechanism does not participate in working in a first half drawing process, the force increasing mechanism supplies upward lifting force to the lower blank pressing die to lock the workpiece to be machined when the workpiece to be machined is drawn to the delta stroke before complete drawing, and then only a sheet matal on the inner side of the blank pressing die participates in drawing, so that forming stress is uniform and stable, and spring-back of the workpiece after die unloading is small.

Description

technical field [0001] The invention relates to the technical field of stamping dies, in particular to a drawing die. Background technique [0002] With the development of automobiles in the direction of lightweight, high-strength steel is widely used in automobile body-in-white due to its high tensile strength and impact resistance. However, the plasticity of high-strength steel is poor, it is easy to crack when deformed, and the deformation resistance is large. At the same time, the yield stress of high-strength steel plate is significantly higher than that of ordinary metal plate, the rebound after forming is also large, and the dimensional accuracy of parts is poor. Studies have shown that increasing the blank holder force when the δ stroke (less than 5mm) before the end of the drawing can control the springback very well. However, the jacking force of the ejector pin of the press cannot be adjusted during the drawing process. It has always been a big problem for practi...

AI Technical Summary

Problems solved by technology

However, the plasticity of high-strength steel is poor, it is easy to crack when deformed, and the deformation resistance is large. At the same time, the yield stress of high-strength steel plate is significantly higher than that of ordinary metal plate, the rebound after forming is also large, and the dimensional accuracy of parts is poor.

Studies have shown that increasing the blank holder force when the δ stroke (less than 5mm) before the end of the drawing can control the springback very well. However, the jacking force of the ejector pin of the press cannot be adjusted during the drawing process. It has always been a big problem for practitioners in the mold industry to significantly increase the blank holder force before the end

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