Patent ID: 8075817

Claim:
An in-line screw type injection molding machine in which a screw in a heating cylinder is rotated to knead and plasticize raw resin while transferring the resin toward a forward end side of the screw to thereby reserve metered molten resin on the front end side, and the screw is moved forward to inject the molten resin into a mold to thereby fill the mold with the molten resin, the in-line screw type injection molding machine being characterized by comprising: a metering motor which is disposed on a rear end side of the screw and rotationally drives the rear end side of the screw; a screw mechanism which includes a nut body attached to the rear end side of the screw and rotating integrally with the screw, and a screw shaft fitted to the nut body, the screw mechanism converting rotational motion of the screw shaft into linear motion of the screw through the nut body; an injection motor which rotationally drives the screw shaft as a constituent member of the screw mechanism; an injection motor drive circuit which drives the injection motor to allow a position of the screw to follow a predetermined position command pattern; a metering motor drive circuit which drives the metering motor to allow rotation of the metering motor to follow a predetermined speed setting pattern; and an adder-subtracter circuit which adds or subtracts a speed setting pattern signal of the metering motor drive circuit to or from a speed command signal of the injection motor drive circuit so as to compensate an axial displacement of the screw caused by the rotation of the metering motor.