Control system for injection moulding machine - has automatic layout with computer, target and ascertained injector speeds, servo-valve and feedback control

摘要

In the control system of injection moulding machines a final control value for a part of the machine which is subject to the control is regulated so that it is the value for a preset moulding condition. In the process an intermediate value is found for operating the regulator; by means of a computer an instruction value is determn. for operating the regulator, based on the intermediate and the pre-set values, by using the instruction value the regulator is then activated and controlled. In the figure the regulating system has the hydraulic pressure control (20) with its pump (21), oil tank (22) and four-gate servo-valve (4). The signal processing arrangement (30) is the computer (5) and a position detector (35). A unit (31) adjusts different machine parameters including the injection speed (Vs). Other features include the speed conversion device (32), the servo-sequence control unit (33), the servo-controller (34), and the various pressures of oil feed (Po), tank (Pt) and screw advance (Pf). ADVANTAGE - The system is highly responsive. Overshoot in either direction is thus eliminated and stability and reliability are maximised.