MOTOR-DRIVEN INJECTION UNIT, DIE-CASTING MACHINE EQUIPPED WITH THE SAME AND MOTOR-DRIVEN INJECTION METHOD

摘要

PROBLEM TO BE SOLVED: To provide a motor-driven injection unit and a motor-driven injection method in which an injection speed suitable for a molding material with a high solidifying speed is obtainable and a surge pressure is securely retained for a given period of time, while keeping the position of an injection piston constant after completion of injection and filling. SOLUTION: The rotational motion of an electric servomotor (1) is converted to the reciprocating motion of the injection piston (8) in a cylinder (9) via a plunger (4) with a ball screw so that the molding material (W) in the cylinder (9) is injected into a mold. A surge pressure controlling means is provided to keep the injection piston (8) in the cylinder (9) immobile when the injection piston (8) is subjected to a preset or more load due to the molding material (W) in the cylinder (9). The surge pressure controlling means is composed of a combination of a rotation controlling means for the electric servomotor (1) and an ascent restraining mechanism for the injection piston (8). Further, a time lag is provided between the initial motion of the plunger (4) and that of the injection piston (8) so that the injection by the injection piston (8) is accelerated. COPYRIGHT: (C)2006,JPO&NCIPI