Patent ID: 8037735

Claim:
A die cushion apparatus of a press machine, comprising: at least one fluid hydraulic cylinder that supports a cushion pad; a pressure detector that detects a pressure of a pressure chamber on a cushion pressure production side of the fluid hydraulic cylinder; at least one fluid hydraulic pump/motor having a discharge opening that is connected through a first pipe to the pressure chamber on a cushion pressure production side of the fluid hydraulic cylinder; at least one electric motor that is connected to a rotating shaft of the fluid hydraulic pump/motor; a die cushion pressure command device that outputs a die cushion pressure command that is previously set; a control device that controls a torque of the electric motor so that a die cushion pressure is a pressure that corresponds to the die cushion pressure command based on the die cushion pressure command and a pressure that is detected by the pressure detector; and a regeneration device that regenerates energy required for a die cushioning action that the cushion pad receives when die cushioning of the press machine is effected as electrical energy through the fluid hydraulic cylinder, the fluid hydraulic pump/motor, and the electric motor.