GB817543A - Improvements in or relating to pressure diecasting - Google Patents

Abstract

817,543. Casting- machines. REGIE NATIONALE DES USINES RENAULT. June 7, 1956 [June 23, 1955], No. 17673/56. Class 83 (1). [Also in Group XXIX] In a method of pressure die-casting mouldable material, a low or medium-pressure fluid is used for opening and closing the mould and for operating a high-pressure pump which delivers fluid at high pressure to an accumulator, which supplies the necessary pressure for injection of the material into the mould. Compressed air is fed from a distributer 2, Fig. 1, through pipe 4 to cylinder 5 to effect mould closing by the crosshead 7. Pistons 8, 9 connected to the crosshead draw in oil from a reservoir 12 through a pipe 13 and non-return valve 14, and drive oil at high pressure through pipes 15, 18, valve 23 and pipes 19-21 into an accumulator 22, whose pressure is set by a pressure-relief valve 25. Operation of an electromagnetic valve and distribuer unit 27, 28, affords a passage for high-pressure oil from the accumulator to the injection-cylinder 29. Reverse operation of the unit 27, 28 restores the machine to its initial position. In a modification, Fig. 2, a pump 34 forces oil from the reservoir 12 at medium pressure into an accumulator 36, the supply of oil therefrom to the mould-closing cylinder, and the pistons 47, 48 attached to the crosshead, being controlled by an electromagnetic valve and distributer 39. A second electromagnetic valve and distributer 57 controls the supply of high-pressure oil from the second accumulator 70 to the injection-cylinder 74. In a further modification, Fig. 3 (not shown), medium-pressure and high-pressure accumulators are provided and controlled in such a manner that the injection-stage commences with medium-pressure fluid, and after actuation of a timing-device, is completed with high-pressure fluid.