Patent ID: 7331208

Claim:
A die cushion controller that controls pressure applied by a die to a workpiece placed on a die cushion member when the die is driven along a press axis, the die cushion controller comprising: a press axis servo motor for driving the die along the press axis; a die cushion servo motor for raising and lowering the die cushion member; and control means for controlling the press axis servo motor and the die cushion servo motor; wherein control of the die cushion servo motor is switched from position control to pressure control and from pressure control to position control according to a position command which is issued to the press axis servo motor by the control means for controlling the press axis servo motor, and the control means for controlling the die cushion servo motor has means for outputting a command that clears a positional deviation, which is a difference between a command position and a detected position, accumulated in a position loop control section in a servo control unit in the control means, at the time of a switchover from pressure control to position control.