Patent ID: 7619384

Claim:
A controller for a die cushion mechanism that generates force on a slide of a pressing machine using a servo motor as a driving source, the controller comprising: a spring element that is displaced according to a force between the die cushion mechanism and the slide; a force instructor that instructs force to be generated between the die cushion mechanism and the slide; a force detector that detects force generated between the die cushion mechanism and the slide; and a speed instruction generator that generates a speed instruction of the servo motor, based on a force instruction value instructed by the force instructor and a force detection value detected by the force detector, wherein the speed instruction generator generates the speed instruction by multiplying a force gain to a force difference determined from a difference between the force instruction value and the force detection value, and the speed instruction generator changes the force gain, based on a spring constant corresponding value of the spring element determined from a force indicator that works between the slide and the die cushion.