GB751292A - Improvements in or relating to the sheathing of electric cables with light metal - Google Patents

Abstract

751,292. Extruding. STANDARD TELEPHONES & CABLES, Ltd. May 28, 1954, No. 15833/54. Class 83 (4). In a process for extruding a sheath of light metal or alloy, particularly aluminium, on to a cable, the extrusion is performed in two stages ; in the first stage a portion of a relatively large billet is extruded to form a smaller billet and in the second stage the smaller billet is extruded through a die around the cable. A cable sheathing press, Fig. 8, has two main billet containers 1, 1<SP>1</SP> from which the billets are extruded simultaneously by hydraulically operated rams 2, 2<SP>1</SP> into a secondary container 5 containing a secondary hydraulically operated hollow ram 10. During the filling of the secondary container the ram 10 is forced away from the die 6 and thereafter the pressure on the main rams 2, 21 is reduced whilst pressure is applied to the secondary ram 10 to extrude the metal from the secondary container 5 through the die 6. The secondary container is then refilled from the main containers. When the main rams 2, 21 have reached the end of their inward travel, the main containers 1, 1<SP>1</SP> are retracted away from the die block 4 by hydraulic motors 14, and-shears 11 operated by hydraulic motors 19 shear off the discards remaining in the main cylinders. The discards are ejected from the containers during the further retraction of the latter with the rams stationary. The main rams 2, 2<SP>1</SP> which may carry dummy blocks are movable transversely by hydraulic motors 13 to permit insertion of the billets into the main containers. Draw-back motors 15 are provided for the main rams. The cable passes through a hollow stem 17 and a guide tube 7 where it is cooled by compressed air. The extruded sheath emanating from the die is cooled by water jets. The die 6 is held in position by a hydraulically operated bolster 18 which may be retracted to permit the die 6 and any residue metal to be moved downwardly out of the secondary container by the ram 10. In another embodiment (Fig. 6, not shown) only one main container is provided. In a further embodiment, Fig. 10, two or more secondary containers 5, 5<SP>1</SP> with solid rams 10 are fed from one or more main containers. The hydraulic motors may be controlled manually or automatically. New billets inserted in the main container or containers will upon extrusion be united with the sheared-off ends of the previous billets.