GB588197A - Improvements in and relating to sparking plugs - Google Patents

Abstract

588,197. Making compound wire and sparking - plug electrodes. MALLORY METALLURGICAL PRODUCTS, Ltd. Feb. 1, 1945, No. 2527. Convention date, Feb. 1, 1944. [Classes 83 (ii) and 83 (iv)] [Also in Group XXVII] Welding; altering molecular structure.-A sparking-plug electrode or the sparking-tip of the electrode is composed of a wire having a core of high thermal conductivity metal and a sheath of material with a high resistance to erosion, the wire being doubled upon itself or folded to form a loop and the ends of the wire being remote from the sparking-area of the electrode. The sparking-tip may be formed from a wire of circular cross-section and be doubled upon itself and swaged so that its doubled section is deformed to form a sparking- tip 15 (Figs. 2 and 3) of circular cross-section, each portion 13, 14 of the wire being substantially of semicircular cross-section. Alternatively, the wire may be formed into a loop (Fig. 4) and the two ends welded to a flange on the end of a central electrode 18 or the end portion of the rod can be bent into a loop and the ends located in a recess 27 in the insulator as shown in Fig. 8. As a further alternative the rod can be flat in cross-section and doubled upon itself to form two portions which lie against one another and the ends can be welded on to a flange on the central electrode. Instead of forming only the tip of the electrode of the doubled wire, the whole electrode may be of this form. The wire may be formed by passing a wire of the core material through an electroplating bath and then hot or cold drawing the sheathed wire formed, the drawing changing its metallurgical structure and increasing its resistance to erosion. Alternatively, a wire of one material can be brazed into a tube of another material followed by drawing to the desired diameter or a tube may be shrunk on to a rim and then heated in a reducing atmosphere to bond the two without fusion or a tube may be filled with a molten metal of a lower melting point than the tube. The following metals are mentioned as suitable for the core : silver, copper, molybdenum. The sheath may be of any of the following : platinum, nickel or a nickel alloy such as nickel-chromium, nickelmanganese, nickel-molybdenum, nickel-ironmolybdenum and nickel-iron-chromium-molybdenum alloys. In addition to the core and coating, the wire may have an intermediate layer of stronger material.