Patent ID: 6334479
Filing Date: 2002-01-01
Classification: B22D

Abstract:
A control system for an injection system of a multiple-slide die-casting machine, the injection system having a hydraulic cylinder for advancing and retracting an injection plunger adapted to introduce a pressurized casting material into a cavity between a plurality of slide mold sections, the control system comprising:means for detecting a position of the injection plunger, including at least one position transducer for detecting at least one position transducer for detecting a predetermined position of the injection plunger where hydraulic cylinder control parameters should be changed from velocity phase in which a velocity of the injection plunger follows predetermined profiles, to a pressure phase in which a net hydraulic pressure applied to the injection plunger is controlled; a servo valve for controlling a flow rate of a hydraulic fluid supplied to the hydraulic cylinder; a controller adapted to selectively control the hydraulic cylinder through the servo valve in a closed loop mold and an open loop mode, in said closed loop mode the controller receives signals from the means for detecting a position of the injection plunger, and forwarding command signals in accordance with the predetermined velocity profile to actuate the servo valve accordingly in the velocity phase, or forwarding command signals in accordance with predetermined pressure profiles to actuate the servo valve accordingly in the pressure phase, and in the open loop mode the controller forwards a constant command signal to set a pre-selected flow rate on the servo valve for a desired constant velocity of the injection plunger; and a control mode selection valve adapted to be activated only when the open loop mode is selected to enable a selected reduced pressure valve pre-set on a pressure reducing valve.