Hydraulic device for the injection unit of a plastic material injection-moulding machine

Abstract

Abstract A hydraulic control system for the operation of three linear and one rotary hydraulic drive assemblies of the injection unit of an injection molding machine, comprising a variable delivery pump supplying drive fluid at a constant pressure gradient to several supply lines controlled by two control units which are arranged in parallel and feature proportional P/Q valves and pressure transducers, a smaller pressure maintenance pump which is controllable by a third proportional P/Q valve and switchable into one of the supply lines, and a hydraulic accumulator for the temporary supply of a large quantity of drive fluid. The proportional P/Q valves convert automatically from their flow rate programs, controlled by displacement-to-voltage converters on the injection unit, to pressure programs controlled by the pressure transducers.

Inventors

• 👤 Karl Hehl

Bibliographic Details