GB1434516A - Metal casting - Google Patents

Abstract

1434516 Vacuum-casting HITCHINER MFG CO Inc 5 June 1974 24957/74 Heading B3F [Also in Division F4] Casting apparatus comprises a crucible 20 in a sealable melting and mold pouring chamber 12, a sealable loading compartment 14 mounted on the chamber, a valve 18 and conduit means 16 between the chambers, a sealable mold container 40 having a bottom opening 42 for sealing around the lower open end 46 of a gas permeable mold 48 supported therewithin and extending downwardly therebeyond, the mold container including upper and lower cup elements 58, 56, power means 64, 68, 70 for supporting the cup elements for relative movement into sealed relationship and for moving the container between the chamber and the compartment, and means 88, 89, 60 for independently varying the pressure of the chamber. The crucible 20 is mounted by load-measuring cells 30 on a platform 26 movable by a hydraulic device 32 on a platform 34 which also supports a closure plate 36. The mould 48 is a refractory gas-permeable shell mould for golf-heads. The riser passage 50 is 1-10 square inches in cross-sectional area and at least five time the area of a gate passage 54. The container 40, the compartment 14 and the chamber 12 are evacuated by pipes 60, 80, 82 and supplied with argon or other inert gas from a bottle 86 through the pipe 60, a valve 89 and a valve 88. In operation, an ingot is melted in the crucible 20 by induction coils 24 while a vacuum of 10 microns is applied. When melted, the metal is stirred by the coils to produce an upward central current and move the dross away from the central area. With the parts positioned as shown, a vacuum of 10 microns is produced in the container 40 and compartment 14 and argon then supplied at 25 inches mercury. The valve 18 is opened and the neck of the mould lowered into the molten metal. When solidification has occurred as shown in Fig. 7, the argon pressure to the container 40 is raised causing the unwanted molten metal to be expelled, leaving the central gate 55 and initial parts of the runners free of metal. The container 40 is then raised and drip doors 76, 78 are closed. A pair of tongs may be temporarily fitted in place of the mould container part 56 in order to lower an ingot to refill the crucible.