GB324789A - Improvements in or relating to electrical induction furnaces - Google Patents

Abstract

324,789. Davis, N. R., and Associated Electrical Industries, Ltd. Jan. 8, 1929. Induction furnaces.-The lining or lagging of a coreless induction furnace is dried out by enclosing within said material a metallic body which is heated by eddy currents when the furnace coil is energized. The metal body is subsequently rendered sufficiently discontinuous to prevent circulation of eddy currents therein during the ordinary operation of the furnace. The metal body comprises a cage formed of strips 1 riveted at the top to a ring 2 and turned inwards at the bottom and riveted to a discontinuous annular plate 3. The parts 5 of the ring 2 between the strips 1 and the parts 9 of the bottom portions of the strips 1 are of reduced cross-section. The ends of the ring 2 are separated by insulation 7. The cage is inserted in the inductor and zircon sand or other lagging material is rammed into the space between them. Ganister is packed between the strips 1 to prevent the sand escaping. The inside of the cage is then lined with silica or magnesite with or without tar. A metal pot may be inserted in the cage and the lining rammed therearound. The cage melts at the restricted portions 5, 9 after the drying out is effected and a vent may be provided to allow the molten metal to escape. The metal pot also melts and is poured out with the melted charge. The remaining portions of the cage may be connected to earth to form a protective screen as described in Specification 323,561. The cage is made of non-magnetic steel or cast iron. A formula is given for the width of the strips.