Patent GB-627815-A (GB)
Title: Improvements in or relating to electric cables
IPC: H01B13/22
Filed: 1947-07-14
Abstract: 627,815. Cable-making machines. JOHNSON & PHILLIPS, Ltd., and HOLLINGSWORTH, P. M. July 14, 1947, No. 18662. [Class 36] [Also in Group XXII] A method of providing an electric cable core with a metallic sheathing comprises threading the core into a laid out length of previously formed tube of the required metal and then reducing the sheathing to the required diameter, drawing off the finished length of cable and simultaneously drawing out the next length of tubing. As shown in Fig. 1, a tube of aluminium is wound off a drum 1 and drawn through a straightening device 2 comprising a number of pulleys 48 between which the tube passes. It then passes to a tow-line threading device 3 which comprises a solenoid through which the tube is led. When the leading end of the tube is over the guide 7 a magnetic armature to which the end of the core tow-line is attached is pushed into the tube where it is held by the magnetic field of the solenoid. A tube tow-line is then secured to the forward end of the tube and the capstan 14, and the tube drawn forward. The armature is held stationary in the device 3, thus drawing the core towline into the tube as the tube moves forward. The tube is drawn along a trough 15 fitted with rollers 16 until the rear end of the tube is just forward of the roller 7. The core tow-line is disconnected from the armature, which is connected to a new core tow-line for use in the second length of tube. The two lengths of tube are then connected by means of a coupling so constructed as to allow the cable core to pass through it to the first length of tube and a core tow-line to pass through it to the second length of tube. A clamp 19 is then clamped to the rear end of the first length of tube, and the core tow-line in this tube is then attached to the forward end of the core, which is reeled off drum 20. The core is then pulled through the tube by means of the core tow-line, and then detached from the tow-line, which is carried back to the feeding end by means of an endless belt 22, ready for use in a third length of tube. The clamp 19 is then loosened and the tube drawn forward so that the leading end passes through the aperture of a swaging machine 23, this drawing the second length along the trough 15. A clamp 24 is applied to the first length of tube and the tube tow-line disconnected, after which the forward end of the tube is swaged and the sinking die 25 slipped on, the tube tow-line then being re-attached, the clamp 24 released and the tube drawn forward again through the sinking die 25 and a de-greasing bath 27 to a reeling drum 29. During the sinking operation the second length of tube is having its core inserted and a third length is brought into position. An alternative method of carrying out the invention is shown in Fig. 15. The core is threaded into the tube as in the first method, except that the reeling drum 29 is used in place of the draw drum 14. A die stand 46 is mounted on a carriage 45 and the swaging machine 23 is located rearwardly of the trough 15. The tube is laid out in the trough 15 after passing through the aperture of the swaging machine, and the rear end of the tube secured by a clamp 19b. The core is drawn into the tube and the clamp 19b then released and the rear end of the tube swaged, and drawn past the die stand 46. The die 25 is slipped on and the rear end of the tube connected to the front end of the second length. The carriage 46 is then moved forward so that the die stand 46 carries the die along the length of the tube. The cable is then cleaned and reeled as previously described, at the same time drawing the second length of tube along to the 'laying out position. Specification 627,793 describes an alternative method of applying an aluminium sheath to a cable core.