Patent ID: 7167501
Filing Date: 2007-01-23
Classification: F27B,F27D,H05B

Abstract:
1. A cold crucible induction furnace for heating an electrically conductive material, the furnace comprising: a wall and a base to form a melting chamber in which the electrically conductive material is contained; at least one ac induction coil at least partially surrounding the height of the wall; an ac power source having its output connected to the at least one ac induction coil to supply ac power to the at least one ac induction coil and generate an ac field around the at least one ac induction coil, the ac field magnetically coupling with the electrically conductive material to inductively heat and at least partially melt the electrically conductive material by induced currents in the electrically conductive material; a magnetic pole piece having a first and second opposing ends, the first end disposed adjacent to the bottom of the base; one or more dc coils disposed at least partially around the magnetic pole piece; and one or more dc power sources connected to the one or more dc coils to generate a dc magnetic field, the dc magnetic field being concentrated by the magnetic pole piece whereby the dc magnetic field penetrates the lower portion of the melting chamber.