Patent ID: 7040377

Claim:
An injection system of a die casting machine for moving forward an injection plunger to inject and fill a molten metal in a cavity formed in a die and raising the casting pressure of the molten metal filled in said cavity for casting, said injection system of a die casting machine comprising: an injection cylinder including an injection piston linked with said injection plunger and a booster piston arranged behind said injection piston, an accumulator for supplying a pressurized liquid of a predetermined pressure, a liquid pressure circuit for supplying the pressurized liquid from said accumulator to said injection cylinder, driving said injection piston, then driving said booster piston, a control valve for controlling a flow rate of the pressurized liquid discharged from the front side of said injection piston of said injection cylinder so as to control a flow rate of said injection piston, a first pressure detecting means for detecting a first pressure of the pressurized liquid at the front of said injection piston, a second pressure detecting means for detecting a second pressure of the pressurized liquid at the back of said injection piston; and control means for inputting the detected first and second pressures, adding the detected first and second pressures to obtain the casting pressure, and closing the control valve before the casting pressure reaches a maximum value defined by a pressure accumulated in the accumulator.