GB739499A - Improvements in or relating to the extrusion of metals - Google Patents

Abstract

739,499. Extruding. COMPTOIR INDUSTRIEL D'ETIRAGE ET PROFILAGE DE METAUX. Aug. 21, 1953 [Oct. 1, 1952], No. 23165/53. Class 83 (4). In the hot extrusion of composite metal billets composed of at least two thicknesses of different metals 29, 30, a layer of glass-like lubricating material 31, 33 which remains viscous during extrusion, is provided respectively between the billet and the container 22 and between the billet and the extrusion die 24. The layer 31 is preferably formed by wrapping a sheet of glass fibre around the billet after the latter has been heated in a non-oxidizing furnace, or preferably in a molten salt bath such as of barium chloride or barium chloride and sodium chloride. The end piece 33 may cornprise one or more glass plates, glass wool or cellular glass. Certain oxides and salts, such as boron trioxide, phosphorus pentoxide or sodium metaphosphate, or certain natural or synthetic slags may be used instead of glass. The billet comprises an inner cylinder 30 of mild steel and an outer cylinder 30 of 18-8 type stainless steel, the two cylinders being welded together at 34. In the extrusion of a composite tube, a layer of lubricating material 32 is also provided between the billet and the mandrel 27. The latter is mounted in a support 28 which is slidable within the ram 25. In another embodiment a bar is extruded from a composite billet composed of three different metals. Billets with cylindrical and conical inner portions are described together with the extruded bars produced therefrom. Comparison is made between the use of grease and graphite and the glass-like lubricants for extruding various forms of billet. A specific example is given of the billet dimensions and pressure used in the extrusion of a composite tube. Specifications 607,285, 661,555, 663,357 and 684,013 are referred to.