GB753935A - Aluminium sheathed cable and method for making same - Google Patents

Abstract

753,935. Sheathing cables; welding by pressure. KAISER ALUMINUM & CHEMICAL CORPORATION. June 8, 1954, No. 16849/54. Classes 83 (2) and 83 (4). A process for continuously applying a protective metal sheathing to cable comprises providing cable with a closely surrounding open seam metal tubing, progressively passing the cable and tubing through an alternating electromagnetic field for inducing A.C. voltage within the tubing and progressively causing the opposed seam edges of the tubing to come into contact with each other, whereby substantially all of the electric current induced in the portion of the tubing within the electromagnet field is concentrated at the point where the seam edges are brought into contact so, as to cause the' seam edges to fuse together. Aluminium strip from a reel 2, after passing through edge trimming shears if necessary, is fed and formed into an open-sealed tube about a cable 4 by skelping rolls 3. A protective strip 6 of aluminium foil, glass or asbestos may be fed on to the cable under the seam. The cable in the open-seamed tube is then passed' through welding means 8 where the seam is held open by a guide pin 10 formed of metal plates suitably insulated from one another, pressing on the cable or protective strip 8 as the tube and cable-pass through a cooled copper high-frequency (2,000-500,000 cycles/sec.) induction coil 9. The seam edges, slightly spaced from the cable, are pressed together by rolls 11 at the exit end of the coil 9 so that substantially all the induced current flows across the seam at this point to effect the welding. Helium or argon may be passed through the coil 9. The welded sheath, after passing through a cooling chamber if necessary is drawn down by rolls 12 to conform more closely to the cable and the sheathed cable is wound up on a reel 13.