Patent GB-738292-A (GB)
Title: Improvements in or relating to metal extrusion presses
Inventor: GRIEVE GEORGE THOMAS WILSON
IPC: B21C33/02
Filed: 1952-10-15
Abstract: 738,292. Extruding. BRITISH INSULATED CALLENDER'S CABLES, Ltd. Oct. 14, 1953 [Oct. 15, 1952], No. 25873/52. Class 83 (4). A metal extrusion press has its container 6 (Fig. 2), supplied with molten metal from a feed chamber 22 through a valve 9 axially movable relative to the container from its seating position against the end 21 to the container to its open position in which an annular passage 27 is provided for the flow of molten metal. The valve is fixed to a stationary cross-head 11 of an hydraulic press. On the valve stem 10 is slidably mounted a sleeve 14 rigidly connected to a tubular extension 13 of the container 6. The extrusion ram 1 is secured to the hydraulic ram 4, Fig. 1, of the press and has a through bore leading to a die-box 2 housing the extrusion die or dies. Molten lead from a lead pot 25 is circulated through pipes 23, 24 and the feed chamber 22 by thermo-syphon action, and is maintained molten in the feed chamber by gas burners 29 housed in a jacket 30. The container 6 is cooled, for solidifying the lead, by the evaporation of water or other liquid in surrounding jackets 31, or by circulation of a coolant liquid through cooling channels in the container wall. A water cooling jacket 32, Fig. 1, is also provided for the ram 1. A bellows-type seal 28 is provided between the valve 9 and the sleeve 14. Alternatively, packing rings may be used between the valve and sleeve or the co-operating surface thereof may be made a close working fit. A flexible bellows 33 is also provided between the ram 1 and the container 6 to prevent ingress of air. Upon the upstroke of the ram the container 6 is moved by friction with the ram until its end wall 21 abuts against the valve ; the lead trapped in the container bore 7 is then extruded through the bore of the ram. On the downstroke of the ram the container is moved downwards by friction with the ram and gravity until the sleeve 14 abuts against a shoulder 19 on the valve. In another embodiment the opening and closing of the valve 9 is assisted by an hydraulic motor 34, 38, Fig. 3 (not shown). In another embodiment, Fig. 4, for a horizontal cable-sheathing press, the container 41 is connected to a hydraulic operating cylinder 42 by a tubular column 43 housing an annular feed chamber 47 supplied through a pipe 86 and equipped with electric heating cables 88. The feed chamber is welded to the adjacent end of the container 41 and to the valve 61 and is sufficiently flexible to permit the valve to open and close the annular passage 63 leading to the bore 53 of the container. The valve is operated by a double-acting piston 50 working in the cylinder 42. The extrusion ram 51 is operated by a double-acting piston 49 also working in the cylinder 42. To perform the extrusion stroke, pressure liquid is supplied to the cylinder 42 between the pistons 50, 49, whereby the piston 50 is moved to the left, thereby causing the valve 61 to close the feed passage 63, and the piston 49 is moved to the right. An annular working surface 54 of the extrusion ram thus presses the lead trapped in the annular space 53 through a number of passages 58, 59 into a chamber 60. From the latter the lead is extruded as a sheath between inner and outer dies 55, 56 carried by the extrusion ram, and around a cable passing through the bores of the ram and its operating piston 49. A cold lead seal is provided between the valve 61 and the ram 51 by annular grooves 79 in the bore of the valve. Cooling liquid is circulated through passages 80 in the valve from two annular manifolds 81. The molten lead in the space 53 of the container 41 is cooled by water or steam supplied to alternate passages of a series of longitudinal passages 82 in the container. Heating of the container when necessary, is effected by heating elements housed in the other alternate passages 82.