Patent ID: 7159639

Claim:
A diecasting machine comprising: a mold clamping cylinder for clamping and opening/closing a mold in a direct-acting manner; a single two-way hydraulic pump driven by a servo driving motor for supplying hydraulic fluid to the mold clamping cylinder in two directions; a hydraulic circuit for driving the mold clamping cylinder by controlling supply of hydraulic fluid from the two-way hydraulic pump to the mold clamping cylinder and discharge of hydraulic fluid from the mold clamping cylinder which proceeds in accordance with movement of a piston of the mold clamping cylinder; and a hydraulic controller for controlling rotational speed of the servo driving motor associated with the two-way hydraulic pump in opening/closing the mold at high speed and controlling torque of the servo driving motor in clamping the mold; wherein, said piston-protruding-side hydraulic fluid pipeline being connected to a piston-protruding-side hydraulic fluid chamber of a mold clamping 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-refracting-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.