GB855876A - Extrusion of metals - Google Patents

Abstract

855,876. Extruding. COMPTOIR INDUSTRIEL D'ETIRAGE ET PROFILAGE DE METAUX. March 14, 1957 [March 28, 1956], No. 8504/57. Class 83 (4). In the production by extrusion of products of small cross-sectional area made of metals which are difficult to extrude, a composite billet is used comprising a thin metal casing, Fig. 1a, of a readily extrudable metal containing one or more elements 3 of the difficult metal to be extruded whose surfaces have been treated to prevent adhesion together or with the casing, the billet being heated and then extruded using a suitable lubricant and the casing being subsequently! removed. For making extruding wires of 18/8 stainless steel, the envelope 1 may be of mild steel closed by welded-on end plugs 2 with air vents 21 and containing a plurality of round or hexagonal stainless steel bars 3 whose surfaces have been coated, by brushing or dipping, with a paste made from sodium silicate, alumina and water. The billet is extruded using vitreous lubricants and the casing is finally removed by slitting it longitudinally. The final product consists of a plurality of separate wires of polygonal crosssection, Fig. 1c (not shown): In another embodiment, Fig. 2a (not shown), a tube of differently extrudible metal is enclosed between tubes 6, 7 of readily extrudible metal and is extruded to produce a thin wall tube 8<1>, Fig. 2c (not shown). The casing may be removed by machining or may be pulled off by force and the surface treatment may alternatively consist of a surface oxidation. A specific example is given.