Die cushion controller

A die cushion controller controlling a servo motor for driving a die cushion disposed in opposition to a slide of a press machine, comprising:

• a pressure command portion which prepares a pressure command value for exerting a predetermined pressure to a press material disposed between the slide and the die cushion;
• a pressure detecting portion which detects an actual pressure exerted on the press material;
• a first speed command portion which prepares a speed command value to be instructed to the servo motor based on the pressure command value prepared by the pressure command portion and the actual pressure detected by the pressure detecting portion;
• a speed detecting portion which detects an actual rotational speed of the servo motor;
• a current correction value preparing portion which prepares a current correction value by multiplying a second order differential value of the pressure command value prepared by the pressure command portion by a coefficient;
• and
• a current command portion which prepares a current command value to be instructed to the servo motor based on the speed command value, the actual rotational speed detected by the speed detecting portion, and the current correction value prepared by the current correction value preparing portion.