Pressure pouring in a vacuum environment

Claim 1

A casting apparatus comprising, in combination, a sealed melting and mold pouring chamber, a sealed vacuum lock compartment mounted on said chamber, valve and conduit means for establishing communication between said melting chamber and said vacuum lock compartment, means for evacuating said melting chamber during melting and pressure pouring and for selectively evacuating said vacuum lock compartment, a furnace mounted and movable within said chamber between a charging position and a pressure pouring position containing a melting crucible adapted to hold molten metal and having a removable sealed cover, an upwardly extending pouring spout externally of said crucible communicating with the bottom of said crucible and having at its other end an annular seat portion having a conical taper, induction heating coils surrounding said melting crucible and said pouring spout, removable tubular refractory nozzle having at one end a conical taper adapted to mate with said conical taper of said seat and to seat of said seat portion and having a conical taper at the opposite end thereof, heat-resistant resilient sealing means between said seat and said nozzle, a permeable refractory mold having a downwardly extending conical portion adapted to mate with said conical taper at said opposite end of said nozzle and to seat on said nozzle, a metallic heat removal and clamping means adapted to hold said nozzle on said seat and to withdraw heat from said nozzle at a desired rate thereby defining a region where said molten metal may solidify in said nozzle, said nozzle being movable on said sealing means to compensate for any misalignment between said mold and said seat to provide a passage between said pouring spout and said mold, said sealed cover having an opening therethrough and receiving a tube means communicating with a source of pressurized gas outside of said chamber for increasing the pressure on the surface of said molten metal in said crucible when said cover is in a closed position to force said molten metal against the force of gravity up said spout through said nozzle and into said mold at a controlled rate whereby said metal enters said mold with a substantially plane front and to hold said metal in said mold during solidification of said metal, and holding means associated with said vacuum lock compartment vertically aligned with said valve and conduit means and being reciprocal between said compartment and said chamber through said valve and conduit, for seating said mold on said nozzle, for holding said mold on said nozzle during pressure pouring, and for raising said molD from said nozzle and into said compartment after said metal has solidified in said mold.