COLD CRUCIBLE

PURPOSE:To obtain a cold crucible where the contact of molten metal to the wall of a crucible is avoided to reduce heat losses during melting and enhance the degree of overheat by providing insulating slits that extend from the wall of the crucible up to the lower part of the bottom, and a core that is located at the center of the bottom and electrically insulated from the periphery of the bottom of the crucible. CONSTITUTION:The bottom of a crucible 1 is almost flat, and insulating slits 3 provided on the wall of the crucible 1 extend below the bottom to allow the induction currents to pass to the inside of the crucible 1. A core 4 is installed at the center of the bottom of the crucible 1 and electrically insulated from the periphery of the bottom of the crucible 1. Therefore, the magnetic voltage on the bottom is high enough to overcome the static head of the molten metal, so that the molten metal is prevented from coming in contact with the crucible even at the bottom. When the core part is made of conductive material, a small amount of induction current flows and heating takes place, so that the bottom absorbs less amount of heat from the molten metal. The use of a fire-resistant material can decrease heat loss and has the advantage of overheating.