Plastic injection moulding control - with two parallel hydraulic supply lines and one programmed pressure control valve

摘要

A hydraulic control system for the injection unit of a plastic injection moulding machine for various pressures is based on two parallel supply lines from a variable displacement pump to the injection cylinder. The first includes a pressure reducing valve, a restrictor valve and an accumulator. The second includes an adjustable restrictor and a directional control valve. The pump control unit, the pressure reducing valve and a pressure relief valve at the junction of the two supply lines are governed by a programme controlled valve. This system requires only one programme controlled pressure regulating valve which is of universal use. The necessary pumping capacity is low but the losses are reduced.