GB1324606A - Extrusion - Google Patents

Abstract

1324606 Extruding WESTERN ELECTRIC CO Inc 30 Sept 1970 [1 Oct 1969 (2)] 46491/70 Heading B3P In a hydrostatic extrusion process the hydrostatic fluid is allowed to flow between the head end surface 67 of the billet 65 and the surface 63 of a die element 62 during extrusion so as to be pressurized and deform the billet in the extrusion zone. The fluid between the surfaces is pressurized by. movement of the die element into the pressure chamber 51 which also causes the fluid at the rear of the billet to be pressurized. The die element 62 is mounted on a plunger 58 and has sealing rings 72, 73. The billet material does not contact the die surface 63. The fluid may be castor oil or silicone oil. The billet is sized to fit closely in the chamber 51 so that there is a restricted or no flow of fluid from the head end of the billet to the rear end. The arrangement is such that if the resistances of the metal increases the spacing of the surfaces decreases and hence the applied fluid pressure increases to automatically keep the extrusion rate constant. The shape of the die surface may be linear or non-linear and empirically determined. In an alternative embodiment, Fig. 7, the fluid acting on the head end of the billet is isolated by seals 95, 97 from the fluid acting on the rear end 116 during extrusion. The seal 95 allows fluid flow between the chambers 87, 99 through a duct 104 before full insertion of the billet. The die element 101 is advanced into the pressure vessel 83 by a ram 106 to effect extrusion. In a further embodiment, Figs. 9 and 10, the die element has a set of outlets 245 on its surface to supply pressurized fluid to a zone of the billet head which has the greatest resistance to deformation. This zone is determined experimentally from a graph of fluid pressure against billet head radius. The die element has bores 246 from a chamber 250 supplied with fluid through a check valve 255. A shoulder 215 defines a second chamber 260 connected by passages 234 to the die surface. When the die element is advanced the fluid flows from the chamber 250 to the chamber 260 via the bores 246 and the die surface.