GB1448277A - Method of hydrostatic extrusion and a machine for carrying out the method - Google Patents

Abstract

1448277 Extruding KOBE STEEL Ltd 19 Sept 1973 [19 Sept 1972 29 June 1973] 43894/73 Heading B3P In a hydrostatic extrusion process a pressure medium is used which can be inserted into the press container in lump form so as to avoid the cooling of the billet caused when a liquid pressure medium is introduced into the container. The pressure medium may be grease such as soap type greases, complex greases, non-soap type greases, or waxes of fats or mixtures of solid lubricants such as molybdenum disulphide, graphite, lead oxide, p.t.f.e. with grease or wax. In one embodiment, Fig. 1, the lump 3 is introduced into the container 1 from a cylinder 5 by a pusher rod 7. The container is preferably heated to below the drop point of the medium and may be cooled during extrusion to keep the temperature down. The billet 11 and die assembly 8, 9 are positioned in front of the retracted container 1, Fig. 1B, which is advanced over them, Fig. 1C, and the stem 2 is then advanced to pressurize the medium 3 and effect extrusion of the billet, Fig. 1D. The lump of pressure medium 3 has an axial groove formed in it by a projecting rod (15), Fig. 2 (not shown), on the pusher plate (6) to allow air trapped between it and the stem 2 to escape. The pusher rod 7 may be hollow, Fig. 5 (not shown), to receive a mandrel (119) when hollow sections are to be extruded. In a further embodiment, Fig. 6, the lump 3 of pressure medium, the billet 11 and the die assembly 8, 9 are arranged in alignment to be received by the container 1 as it is advanced thereover. In a final embodiment, Fig. 7, the lump loading device 28 and the billet loading device 29 are provided on a slide 26 moved to bring each device successively into the centre line CL of the press. The lump 28f is loaded by an hydraulic cylinder 28a from a cylinder 28b. The billet 30 is loaded into the die 29b by an hydraulic pusher 31. The cylinder 28b is reloaded with a pressure medium lump 28f remote from the centre line CL, Fig. 9 (not shown). A pad of heat insulating cloth of silica glass fibres or rubber may be used behind the billet.