GB1012388A - Extrusion apparatus - Google Patents

Abstract

1,012,388. Extruding; billet piercing. BALDWIN - LIMA - HAMILTON CORPORATION. Aug. 28, 1963 [Aug. 28, 1962], No. 34130/63. Headings B3H and B3P. An extrusion die assembly comprises a die body 34 housing a removable die insert 64 made of a ceramic or a cermet, mounted so that the radial forces thereon are equalized towards the end of the extrusion stroke. The die body 34 which may be of metal or a ceramic or a cermet, is mounted within a liner 28 of a billet container 12 and has a well 42 to receive the insert 46 which may be of aluminium oxide fired at 2750‹ F. The mounting of the insert provides during extrusion a low pressure zone 50 to which is supplied under pressure through check valves 55, 57 and ducts 52, 54 a flowable medium such as grease, flaked graphite, soapstone or mica which acts on the outside of the insert and also facilitates the flow of billet metal 60. This may be steel heated to 2200‹ F. and is extruded by a dummy block 16 and stem 14 connected to a piston working in an hydraulic cylinder 22, Fig. 1 (not shown). A piercing mandrel 18 may be attached to the stem or actuated separately. The mandrel is shaped to provide a low pressure zone 64 which may be supplied with lubricant through passages 66, 68. Lubricant may also be supplied to a further low pressure zone at the junction of the die body and liner, Fig. 3 (not shown). The fluid in well 42 surrounding the insert 46 is subjected to the pressure in zone 50 which increases towards the end of extrusion causing an increased radial inward pressure on the insert to equalize the outward radial pressure produced by the extruded metal. After extrusion, pressure air is passed through ducts 52, 54. In another embodiment, Figs. 4, 5 (not shown), the insert 46 is mounted for limited axial movement to act as a valve member for interrupting the flow of lubricant into the zone 50 if pressure builds up due to generation of gases produced by contact of lubricant with the extrusion metal.