Improvements in or relating to extrusion of metals

Abstract

Abstract 607,285. Extruding. SOC. D'ELECTROCHIMIE, D'ELECTRO-METALLURGIE, ET DES ACIERIES ELECTRIQUES D'UGINE, and COMPTOIR INDUSTRIAL D'ETIRAGE ET PROFILAGE DE METAUX. April 11, 1945, Nos. 9069 and 9070. Convention dates, Nov. 22, 1941, and July 11, 1942. [Class 83 (iv)] In a method of extruding hot ingots, there is inserted between the ingot and the die or, in addition, between the ingot and other parts of the container an incombustible material which will melt at the working temperature, but will remain viscous and serve as a lubricant. Suitable materials are glass, oxides such as boron trioxide or phosphorus pentoxide, a salt such as borax or sodium metaphosphate, and certain natural or synthetic slags. In one form, Fig. 1, a glass plate 1 is put into a container 3 between the die 5 and the ingot 6 which is extruded through the die opening 4 by a ram 7. When extruding a tubular ingot 6 between'a die 3 and mandrel 10, Fig. 2, the mandrel may be surrounded by a glass tube 11 while annular glass plates 8 and 12 are placed between the ingot and ram and between the ingot and die. The die may be formed with a number of recesses 22 in its front face, Fig. 6, and with an annular recess 24 in the die opening in front of the narrowest portion. Such recesses serve as reservoirs for the viscous material and by improving lubrication, add to the life of the die. Instead of the material being used in the form of plates or tubes, it may be applied in powdered form, or as a solution or suspension of the material in a fluid which will evaporate in contact with the ingot or container. Alternatively, the hot ingot may be immersed in a bath of the molten material, the bath being used also to preheat the ingot. The work produced by the method is covered with a thin coating of the glass or other material which can be removed by mechanical action or by a suitable solvent. Specification 128,876, [Class 83 (iv)], is referred to.

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