GB754591A - A method for the extrusion of rod-shaped or pin-shaped metal articles, particularly sparking plug electrodes - Google Patents

Abstract

754,591. Extruding. BOSCH GES., R. June 4, 1954 [June 6, 1953], No. 16545/54. Classes 83 (2) and 83 (4). In a manufacture by extrusion of a rod-shaped article, Fig. 3, having a cup or beaker-like portion 6 of hard metal with an inner portion 7 of softer metal, a pair of blanks 6, 7, Fig. 1, of different metals and different hardnesses are placed one above the other in the bore 2 of a die 1 with a softer metal blank 7 adjacent the extrusion ram 8, and are extruded through a die orifice 3 having a frusto-conical approach surface 5 which is so tapered that the hard metal blank 6 is formed into the beakerlike portion surrounding the softer core 7. The blank 7 is preferably of copper and the blank 6 of nickel which is coated with copper to promote close union of the two blanks and to facilitate the flow of nickel through the orifice 3; when blocks of other metals are used they may both be coated. The two blanks may be inserted separately into the bore or they may be soldered or welded together. Alternatively a layer of a substance such as an alloy consisting of lead, tin and/or bismuth may be placed between the blanks and may be connected with one or both blanks by soldering, fusion or pressure welding or by a galvanizing process; this alloy promotes the close union of the blanks during extrusion. The extruded article may be expelled from the die by an ejector or it may adhere to the punch so as to be withdrawn therewith. The extruded article is preferably used as the centre electrode of a sparking plug, Fig. 6 (not shown).