GB928063A - Improvements in or relating to die casting machines - Google Patents

Abstract

928,063. Casting-machines. DIE CASTING MACHINE TOOL Ltd., and A. R. MILLS. April 3, 1962 [April 12, 1961], No. 13198/61. Class 83 (1). In a pressure die casting machine with fixed and movable die plates 10, 11, respectively, the die evacuation means is in the form of an extraction pump 28 and reservoir 27 connected to the fixed die plate 10 via a solenoid-operated valve 25. The energizing of the solenoid 23 to open the valve 25 is effected by a micro-switch 22 on the movable die plate when the dies are closed. The evacuation of the die cavity 14 is co-ordinated with the position of injecting plunger 17 so that when the dies are closed evacuation is effected with plunger 17 positioned to close the entry port of pipe 21 to prevent molten metal being drawn through said pipe. The plunger is then withdrawn beyond said entry port for a predetermined time to permit a given quantity of molten metal 15 to be drawn into the injection cylinder 18 for subsequent discharge by the plunger into the die cavities. The forward movement of the plunger may also be time controlled in respect of the die opening, whereby said plunger may form a means of ejecting the cast article. The timing of the operation is controlled by a timing unit 30 which controls a change-over valve 20 of the plunger operating assembly 19 and the operation of die-closing cylinder 13. In a further embodiment of a goose-neck type a bypass passage is incorporated in the plunger to permit the replenishment of the injection cylinder so that said plunger need not itself entirely uncover the feed port from the molten metal reservoir.