Hydraulic drive system of an injection molding machine

摘要

Disclosed is a hydraulic drive system of an injection molding machine which has a hydraulic power source equipped with a fixed-displacement hydraulic pump and a servomotor for driving the hydraulic pump and functioning to control discharge rate and discharge pressure of the hydraulic pump through control of the rotational speed of the servomotor. In the hydraulic drive system, a pilot port of a control valve connected to a hydraulic actuator of the injection molding machine is connected to a supply line of working fluid discharged from the hydraulic power source, via a series circuit including a check valve for preventing backflow from the pilot port and a changeover valve.