GB801546A - Improvements in or relating to induction heating methods and apparatus - Google Patents

Abstract

801,546. Induction heating. AMERICAN RADIATOR & STANDARD SANITARY CORPORATION. Nov. 24, 1955 [Feb. 14, 1955], No. 33676/55. Class 39(3) In an induction heater comprising several coil assemblies, each assembly consists of a split metallic sleeve 1, the longitudinal edges of the split being joined by a member 3 to strengthen the sleeve. The member 3 may be of ceramic material, and insulating material such as mica or asbestos 4 is provided between the sleeve and a coil unit 5 which consists of turns of copper insulated from each other by glass tape. The coil turns may be hollow where it is necessary to provide cooling water. The coil assemblies are joined together by spacer members 8 made of a fibrous or other dielectric material and the coil adjacent the end of the heater, where the workpieces enter, has more than one layer of conductor to produce a stronger magnetic field in this area. A tubular insert 11 is of metal, preferably non-magnetic, and its internal diameter is such that the workpieces, e.g. rivets, just pass through without binding. The passage of the workpieces through the insert 11 may be controlled by tilting. Any tendency for workpieces of magnetic material to remain in the discharge end of the insert 11 as a result of their regaining magnetic properties when cooling is avoided by extending the insert beyond the end of the last coil assembly and thus preventing surface cooling of the workpieces. The sleeve 1 may alternatively comprise a ceramic or other refractory member which has circumferential continuity. More than one tubular insert may be provided, Fig. 7 (not shown), and in a further construction, Fig. 8 (not shown), the tubular insert, which may be other than circular in cross section, has a split throughout its length. The apparatus may be energized by 60 cycle alternating current.