Press machine

A press machine comprising:

• a hydraulic cylinder configured to reciprocate a slide between a top dead center and a bottom dead center of the slide;
• a plurality of hydraulic pumps/motors configured to rotate in forward and reverse directions so as to supply a working fluid to the hydraulic cylinder or suck the working fluid from the hydraulic cylinder, the plurality of hydraulic pumps/motors each including a first port connected to a first pressurizing chamber of the hydraulic cylinder that drives the slide in a forward direction;
• a plurality of servomotors axially connected to rotating shafts of the plurality of hydraulic pumps/motors respectively;
• a first pressure source having a constant pressure equal to or higher than 0.3 MPa and connected to each of second ports of the plurality of hydraulic pumps/motors;
• a second pressure source having a constant pressure equal to or higher than 1 MPa and connected to a second pressurizing chamber of the hydraulic cylinder that drives the slide in a reverse direction;
• a slide position commander configured to output a slide position command signal for the slide;
• a slide position detector configured to detect a position of the slide and output a slide position signal;
• and
• a slide position controller configured to control the plurality of servomotors so that the position of the slide matches a position corresponding to the slide position command signal based on the slide position command signal and the slide position signal,
• wherein the slide position controller includes a feedforward compensator that receives the slide position command signal as an input signal, and causes a feedforward compensation amount calculated by the feedforward compensator to act on a torque command signal of the plurality of servomotors calculated based on the slide position command signal and the slide position signal, and
• wherein the feedforward compensator calculates the feedforward compensation amount by a differential element and a proportional element.