GB1304305A - - Google Patents

Abstract

1304305 Casting machines MAHLE-WERK GmbH 18 Aug 1971 [26 Aug 1970] 38674/71 Heading B3F In a pressure die casting machine in which the mould halves 22 and 21 are moved together by an hydraulic drive acting through a toggle linkage 14, the injection of the casting material into the mould is initiated only if the pressure developed in the cylinder 16 of the hydraulic drive reaches a predetermined minimum. The machine has switch devices 40, 50, 60 and 70 provided with switches 41, 51 and 52, 61 and 71 respectively. Switch 71 is open when the mould is completely opened and is otherwise closed. The switch 41 is closed by a cam 19 when the mould halves are normally just in contact with one another. Switches 51 and 52 are opened and closed respectively when the hydraulic drive has reached the position in which the toggle lever mechanism is completely extended i.e. when the mould is normally fully closed. The switch 61 is closed when the pressure in the cylinder 16 reaches a predetermined minimum. This pressure corresponds to a maximum pressure which is developed in the cylinder 16 shortly after the mould halves just contact one another but before the toggle lever mechanism is fully extended. When the machine is operating normally, the switches 41 and 61 close thus energizing the relay 80 which in turn closes the switches 81 and 82; the relay will now remain energized even if the switches 41 and 61 open again. When the toggle is completely extended, switch 52 closes and energizes a contactor 90 which in turn closes switch 91 and operates a solenoid to initiate the injection of molten material into the mould. If for any reason the pressure in the hydraulic cylinder 16 does not reach the required minimum value, switch 61 does not close, thus preventing energization of the relay 80 and-injection of the casting material.