Patent ID: 8127590

Claim:
A die-cushion device of a press machine comprising: a liquid-pressure cylinder which supports a cushion pad, the cushion pad configured to lower as a result of a collision with a slide of the press machine; a proportional flow-rate control valve provided in a flow passage connected to a lower chamber of the liquid-pressure cylinder; a die-cushion pressure command device which outputs a die-cushion pressure command set in advance; a slide speed detecting device which detects a slide speed of the press machine; and a control device which controls a flow rate discharged from the lower chamber of the liquid-pressure cylinder by controlling an opening degree of the proportional flow-rate control valve, wherein the control device controls the opening degree of the proportional flow-rate control valve before the cushion pad starts lowering so that the die-cushion pressure becomes a pressure corresponding to the die-cushion pressure command from the time of lowering of the cushion pad resulting from the collision, wherein the controlling of the opening degree is based on the die-cushion pressure command and the slide speed detected by the slide speed detecting device.