Method and apparatus for controlling injection of injection molder

Abstract

Abstract PURPOSE:To smoothly perform the change-over from rate control in the injection step to pressure control in the follow-up pressure, by inputting an output signal from a previous amplifier selectively into a torque motor to control the rate of a screw and the pressure of the injection cylinder. CONSTITUTION:In a hydraulic controlling valve a, by driving a power amplifier b, the opening between a port P and a port B, and the port B and a port T, that is, the opening of throttles C3, C4 can be varied, and thus the controlled hydraulic pressure is led from the port B to an injection cylinder g to drive the screw j. When the rate control is required, the control mode change-over switch h has been switched to be connected to the previous amplifier c in advance. The hydraulic oil entered into the port P of a hydraulic controlling valve a from a main hydraulic source i is divided into a hydraulic stream that flows from the port T to a tank m and a hydraulic stream that flows from the port B to the injection cylinder g. Accordingly when the torque motor M of the hydraulic controlling valve a is driven by the power amplifier b, the displacement rate of the screw j connected to the injection cylinder g can be varied.

Inventors

• 👤 Toshio Inami

Bibliographic Details