Motor drive injection unit, die cast machine having the unit, and motor drive injection method

Abstract

In a motor drive injection unit and a motor drive injection method, which can obtain an injection speed suitable for a molding material having fast solidifying speed as well as can securely carry out pressure keeping for a predetermined period of time while making a position of an injection piston unmovable after injection and filling are completed, a molding material in a cylinder is injected into a metal mold by converting a rotational motion of an electric servo motor into a reciprocating motion of an injection piston in the cylinder through a plunger with a ball screw, a surge pressure control means is provided for placing the injection piston in the cylinder in an unmovable state when at least a predetermined amount of a load is applied to the injection piston by the molding material in the cylinder, the surge pressure control means includes a combination of rotation control means of the electric servo motor and an upward movement suppression mechanism of the injection piston, and further, an injection speed of the injection piston is increased by providing a time difference between initial motions of the plunger and the injection piston.

Dependencies are inferred from the claim text.