Die cushion system for press machine

Abstract

The present invention relates to a die cushion system for press machine, wherein the height level of an upper pressing module horizentally controls the heigth level of the lower pressing module. The die cushion system for press machine comprises: a hydraulic cylinder supporting and driving a press die; a proportional flow control valve supplying working fluid to a lower port of the hydraulic cylinder to raise it and receiving the working fluid within the hydraulic cylinder for discharging it while the hydraulic cylinder is being lowered; a constant pressure supplying means supplying pressured fluid to an upper port of the hydraulic cylinder to lower the hydraulic cylinder; and a controller controlling operation of the proportional flow control valve to adjust lowering and raising of the press die according to the position of the press slide through a slide position detector and a die cushion position detector, and during the lowering process of the press slide, the controller enabling the press die to exert multi-level reacting force onto the press slide.

Description

technical field [0001] The present invention relates to a die cushioning system for a press in which the height level of a lower punching die is controlled relative to the height level of an upper punching slide in a press machine performing punching, drawing, etc. of a metal plate. Background technique [0002] As can be seen in Korean Patent Application Publication No. 2007-0085303 (publication date: August 27, 2007), a conventional die cushioning system for a press has a flow control valve and a flow supply pump to achieve die cushioning The height level at which the piece moves up and down. However, the response speed in this system is so slow that only a relatively simple pattern of forming pressure can be achieved, where the stamping slide only receives a pressure varying from a high level to a low level (see publication of the Korean patent application image 3 ). [0003] However, in a metal sheet that has been formed by such a simple pattern of forming pressure, th...

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Problems solved by technology

However, the response speed in this system is very slow, so that only a relatively simple pattern of forming pressure can be realized, wherein the stamping slide only receives a pressure varying from a high level to a low level (see the publication of the Korean patent application image 3 )

[0003] However, in sheet metal that has been formed by this simple pattern of forming pressure, there may be elastic recovery and residual stress, which will lead to defects in the formed product

[0004] In particular, during press forming such as deep drawing of high-strength steel sheets, in operations that require significant changes in plastic deformation, conventional die cushioning systems that only apply such a simple pattern of forming pressure may cause tearing of the formed product

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