GB717354A - Resistor protected with resin insulating material and method of making the same - Google Patents

Abstract

717,354. Electric resistor enclosed by moulded casing; mounting terminals. CANEGALLO, G., and S.E.C.I. SOC. ELETTROTECNICA CHIMICA ITALIANA. April 4. 1952, [Sept, 15, 1951.] No. 8701/52, Classes 37 and 38(1). [Also in Group V] The terminal leads are maintained in faceabutting contact with a resistance-coated type resistance element by a casing of natural or synthetic resin moulded around the resistance element. In Fig. 7 a tube P of synthetic resin containing the resistance element R is inserted in a tubular moulding tool O surrounded by a heating coil S. The tube P projects beyond the ends of the resistance element R and axial leads F within carriers N are inserted so as to contact the ends of the resistance element R with or without the aid of a conducting paste M. The heating coil S is operated to soften or plasticize the tube P and the terminal carriers N are pushed inwards to press in the leads F and compress the projecting parts of the tube P around the ends of the resistance element R and axial leads F. When the tube P has set in its new form the assembly is pushed out of the moulding tool O and the product comprises ,tube P moulded around and pressing the axial leads F into firm contact with the resistance element R. Prior to moulding the tube P the resistance coating may itself be coated with a protective layer of insulating varnish or lacquer either alone or mixed in suitable proportions with inert powders of iron oxide, silica or titanium dioxide. The terminal leads F may be bent or cranked, Figs. 3 and 4, or have headed ends, Figs. 5 and 6. In Fig. 2 the ends of the resistance element R are cone-shaped. The conducting paste M may consist of (i) lead or lead alloys or (ii) synthetic resins mixed with powdered metals or graphite. The resistance element R may comprise a glass, quartz or ceramic rod having e.g. a metallic coating or a cracked-on carbon coating.