Patent ID: 7845205

Claim:
A die cushion controller for controlling a servo motor to drive a die cushion disposed in opposition to a slide of a press machine, said die cushion controller comprising: a pressure command portion for preparing a pressure command value corresponding to a predetermined pressure to be exerted on a press material disposed between the slide and the die cushion; a pressure detecting portion for detecting an actual pressure exerted on the press material; a speed correction value preparing portion for preparing a speed correction value by multiplying a differential value of the pressure command value prepared by the pressure command portion by a coefficient; a first speed command portion for preparing a first speed command value based on (i) the pressure command value prepared by the pressure command portion, (ii) the actual pressure detected by the pressure detecting portion, and (iii) the speed correction value prepared by the speed correction value preparing portion; a position command portion for preparing a position command value corresponding to a predetermined position to which the die cushion is to be moved by the servo motor; a position detecting portion for detecting an actual position of the die cushion; a second speed command portion for preparing a second speed command value based on (a) the position command value prepared by the position command portion and (b) the actual position detected by the position detecting portion; and a control mode switching portion for switching between the first speed command portion and the second speed command portion to output the first speed command value or the second speed command value, respectively.