Furnace for directional solidification casting

Claim 1

In a directional solidification melting and self-casting apparatus of the withdrawal type including a furnace, means to supply electric power to the furnace, means to control the electric power to control heat within the furnace, means to move a mold into and out of the furnace and means to maintain desired atmospheric conditions within the apparatus, the furnace being of a multi-zone, enclosed, insitu charge melting and self-casting type comprising, in combination: a resistance heated zone; and an induction heated zone; the resistance heated zone being a directional solidification casting furnace including: (a) resistance heated walls having an inner surface which defines a lateral boundary of a resistance heated hollow interior, (b) a stationary chill disposed peripherally substantially vertically beneath said walls, (c) a peripherally disposed radiation baffle disposed between said walls and said stationary chill, and (d) a platform disposed axially within the apparatus and movable vertically and adapted to carry a casting mold into which molten metal is disposed; the improvement wherein: the induction heated zone is disposed above, aligned with and communicates directly with the resistance heated zone to define the resistance heated zone as a lower zone and the induction heated zone as an upper zone, the upper zone including: (a) upper walls having an inner surface enclosing an upper hollow interior substantially vertically aligned and coextensive with the resistance heated hollow interior and carrying at said inner surface an open bottom induction heating coil about the periphery of the upper hollow interior the inner surface of the resistance heated walls and the inner surface of the upper walls defining a substantially continuous inner furnace wall adapted to be in close proximity to lateral walls of the casting mold carried by the platform, and (b) a furnace top member disposed across the upper walls and upper hollow interior to define an upper boundary of the hollow interior.