INJECTION PRESSURE CONTROLLER OF MOTOR-OPERATED INJECTION MOLDING MACHINE.

摘要

An injection/dwelling pressure controller capable of producing a high-quality moulded article without using any expensive die pressure sensor. When a plurality of points for defining a target injection/dwelling pressure curve represented by a function of an elapsed time after the start of injection are inputted sequentially and manually, the processor (109) of a numerical controller (100) calculates a gp. of target injection/ dwelling pressure data on the basis of a target pressure curve displayed on the screen of a display (113) and stores them in a look-up table in a common memory (102). A comparator (11) connected to a pressure sensor (4) disposed on an injection screw (1) for detecting an actual injection/dwelling pressure is connected to the numerical controller through a first change-over switch (6) at the start of the injection. The target pressure data are sequentially read out from the look-up table and sent to the comparatorand an injection servo motor (2) is driven and controlled by a torque control unit in a servo circuit (200) which operates in response to the comparator output representing the difference between the actual pressure and the target pressure. Accordingly, an injection/dwelling pressure is always regulated to a suitable value on a closed loop basis and the quality of a moulded article can be improved.