Patent ID: 7918120

Claim:
A die cushion controller, comprising: a pressure command signal output unit that outputs a pressure command signal corresponding to a pressure target value based on a predetermined pressure pattern; a pressure detector that detects a pressure applied to a die cushion pad; a pressure comparing unit that outputs a pressure deviation signal corresponding to a deviation between the pressure target value based on the pressure pattern and a pressure detection value based on a pressure detection signal from the pressure detector; a pressure control unit that outputs a first speed command signal based on the pressure deviation signal; a position command signal output unit that outputs a position command signal corresponding to a position target value based on a predetermined positional pattern; a position detector that detects a position of the die cushion pad; a position comparing unit that outputs a position deviation signal corresponding to a deviation between the position target value based on the positional pattern and a position detection value based on a position detection signal from the position detector; a position control unit that outputs a second speed command signal based on the position deviation signal; a position/pressure control switching unit that selects the first speed command signal or the second speed command signal; a speed control unit that outputs a motor current command signal based on the first speed command signal or the second speed command signal from the position/pressure control switching unit; and a servo amplifier that supplies an electric servomotor which drives a die cushion with an electric current corresponding to the motor current command signal, wherein the position/pressure control switching unit compares the first speed command signal and the second speed command signal and selects a smaller one of the first speed command signal and the second speed command signal.