Device for judging collision of a die cushion mechanism and system for judging collision

摘要

A device (110) for judging the collision of a slide (24) with a die cushion in a die cushion mechanism (20) which produces a force against the slide in a press machine using a servo motor (18) as a drive source, comprising force detection means (21) for detecting a force produced between the die cushion and the slide; and comparator means (95) for comparing a force detection value (Fd) detected by the force detection means with a predetermined threshold value (L1); wherein, when the force detection value becomes greater than the threshold value, it is so judged that the slide has come into collision with the die cushion. Thus, the collision is judged within a short period of time and reliably. The collision may be judged by comparing differentiated values (Fd', Fd") of the force detection value, slide position detection value (Y1d) or slide position instruction value (Y1c) or other related threshold values. There can be further used a system for judging a collision which executes a plurality of methods for judging the collision.