GB787874A - Improvements in and relating to electric induction heaters - Google Patents

Abstract

787,874. Heating by induction. DEUTSCHE EDELSTAHLWERKE AKT.- GES. Oct. 19, 1955 [Oct 20, 1954], No. 29902/55. Class 39(3) [Also in Group XXX] An induction heater comprises a non- metallic work chamber 3 preferably of silicon carbide, the chamber being surrounded by a work coil 1 which may be of copper tubing and water-cooled. The reduced thickness of the wall of the chamber at 5 and the gap between this portion and the faces 2a of the workpiece permit a heat loss of a similar order to that resulting from the contact of the thicker portion 4 of the chamber with the workpiece, and more even general heating of the workpiece results. In a modification, Fig. 2 (not shown), the thickness of the chamber wall is further reduced such that the heat loss in this region corresponds to additional heat loss by a liquid-cooled conveyer or a conveyer formed of ceramic. Alternatively, cooling means may be provided in the chamber wall opposite the conveyer. In a further construction, Fig. 6, a chamber shell 3 may be made of mica or asbestos and have liner portions 19 of silicon carbide on which the workpiece is supported. Fig. 7 shows a portion of a reciprocating conveyer of ceramic which has apertures 21 to allow scale from the workpiece to fall through on to the shell from where it is swept out of the chamber by ribs 20 on the return stroke of the conveyer.