Patent ID: 7004224

Claim:
A diecasting machine comprising: an injection cylinder for loading molten metal into a mold cavity by injection; a single two-way hydraulic pump driven by a servo driving motor for supplying hydraulic fluid to the injection cylinder in two directions; a hydraulic circuit for driving the injection cylinder by controlling supply of hydraulic fluid from the two-way hydraulic pump to the injection cylinder and discharge of hydraulic fluid from the injection cylinder which proceeds in accordance with movement of a piston of the injection cylinder; and a hydraulic controller for controlling rotational speed of the servo driving motor associated with the two-way hydraulic pump in injection/loading the molten metal and controlling torque of the servo driving motor in dwelling; wherein, said piston-protruding-side hydraulic fluid pipeline being connected to a piston-protruding-side hydraulic fluid chamber of an injection cylinder; a piston-retracting-side hydraulic fluid pipeline being connected to a piston-retracting-side hydraulic fluid chamber; said two-way hydraulic pump being connected in between said piston-protruding-side hydraulic fluid pipeline and said piston-retracting-side hydraulic fluid pipeline; said piston-protruding-side hydraulic fluid pipeline and piston-retracting-side hydraulic fluid pipeline are connected by a common pipeline; a tank pipeline disposed in said common pipeline for causing hydraulic pressure to return to a hydraulic fluid tank and for causing hydraulic fluid to be suctioned from said hydraulic fluid tank; a check/one-way valve disposed on a piston-protruding-side hydraulic fluid pipeline side section of said common pipeline; and a check valve disposed on said piston-retracting-side hydraulic fluid pipeline side section of said common pipeline, said check valve inhibiting hydraulic fluid from returning in a direction of said tank pipeline.