Method and apparatus for casting vertically stacked magnet bodies

Claim 1

A PROCESS FOR CASTING A PLURALITY OF STACKED METALLIC BODIES HAVING DIRECTIONALLY ORIENTED COLUMNAR GRAIN STRUCTURE COMPRISING: PROVIDING AN ASSEMBLY HAVING A CHILL MEMBER, A PLURALITY OF TIERS OF REFRACTORY MOLDS VERTICALLY DISPOSED THEREON AND A RISER MEMBER UPON THE UPPERMOST OF SAID TIRES, SAID TIERS EACH HAVING A PLURALITY OF CLOSELY SPACED APART MOLD CHAMBERS, THE MOLD CHAMBERS OF ADJACENT TIERS EACH BEING INTERCONNECTED BY CENTRALLY DISPOSED VERTICAL GATE PASSAGES OF LESSER CROSS-SECTIONAL AREA THAN THE MOLD CHAMBERS AND THE MOLD CHAMBERS OF THE TIER ADJACENT SAID CHILL MEMBER EXTENDING UPWARDLY THEREFROM, SAID RISER MEMBER PROVIDING A RESERVOIR CHAMBER SUBSTANTIALLY CLOSED TO ATMOSPHERIC HEAT LOSS COMMUNICATING WITH AND DISPOSED ABOVE THE MOLD CHAMBERS OF THE UPPERMOST OF SAID MOLD TIERS, SAID MOLD TIERS EACH HAVING A MOLD PATTERN PORTION DEFINED BY THE PERIPHERY OF THE OUTERMOST MOLD CHAMBERS AND A REINFORCING PORTION EXTENDING THEREABOUT WITH A RATIO OF MOLD CHAMBER CROSSSECTIONAL AREA TO THE AREA OF SAID MOLD PATTERN PORTION OF GREATER THAN ABOUT, 1:3, PREHEATING SAID TIERS OF MOLDS AND RISER MEMBER TO A TEMPERATURE OF ABOUT 1200-2700* F.; INTRODUCING SUPERHEATED ANISOTROPIC FERROUS MAGNET ALLOY INTO SAID MOLD CHAMBERS AND SAID RESERVOIR CHAMBER IN AN AMOUNT SUFFICIENT TO FILL SAID MOLD CHAMBERS AND PROVIDE A RESERVOIR OF SUPPERHEATED ALLOY ABOVE SAID MOLD CHAMBERS, SAID ALLOY HAVING BEEN SUPERHEATED TO A TEMPERATURE OF AT LEAST 200* ABOVE THE LIQUIDUS POINT BUT BELOW THE POINT AT WHICH TWIN GRAIN FORMATION OCCURS, SAID MOLD AND ALLOY TEMPERATURES BEING SELECTED TO PROVIDE A STEEP THERMAL GRADIENT DURING EXTRACTION OF THE SUPERHEAT AND HEAT OF SOLIDIFICATION OF THE ALLOY IN SAID MOLD CHAMBERS WHILE MINIMIZING TRANSVERSE HEAT LOSS THEREFROM, SAID RESERVOIR OF SUPERHEATED ALLOY IN SAID RESERVOIR CHAMBER PROVIDING A RESERVOIR OF HEAT FOR THE METAL IN SAID MOLD CAVITIES TO AVOID PREMATURE CHILLING THEREOF AND TO ENABLE SOLIDIFICATION TO OCCUR THROUGH EXTRACTION OF THE HEAT FROM THE MOLTEM METAL IN SAID MOLD CHAMBERS THROUGH SAID CHILL MEMBER; AND ALLOWING SAID METAL TO COOL BY EXTRACTION OF HEAT THROUGH SAID CHILL MEMBER TO FORM MAGNET BODIES HAVING A UNIDIRECTIONALLY ORIENTED COLUMNAR GRAIN STRUCTURE.