GB862959A - Improvements in or relating to electric heaters - Google Patents

Abstract

862,959. Electric heating resistances. THERMEL Inc. March 19, 1957 [March 26, 1956], No. 8994/57. Class 39 (3). [Also in Group XXII] An electric heating resistance A. C, Fig. 9, of the type made by inserting a resistance wire within a conductive sleeve packed with refractory insulation such as magnesia larger than 325 mesh and swaging, is mounted in a thermally conductive retainer 100,102 shaped to form a heating surface and the retainer and sleeve are bent to an arcuate shape with the heating surface 20a on the concave side of the retainer. The copper or aluminium retainer may be extruded in a form with grooves 21<SP>1</SP>, Fig. 4 in which the resistances 10 are placed, and the outer lips 22<SP>1</SP>, 23<SP>1</SP> are then bent over. In another form the resistances are held in the grooves by a backing member 38, Fig. 5 having aluminium mating strips 39, 40, 41 for each groove and a backing band 42 of less conducting metal such as stainless steel. Alternatively the resistances may be inserted into passages 51, 52, Fig. 7, and consolidated by swaging; the grooves between the resistances may be omitted leaving the retainer as a plain block. A resistance unit suitable for receiving a cooking pot or other articles to be heated is made by joining two curved retainers by spring-loaded tie-bolts 105, Fig 9.