Patent GB-926740-A (GB)
Title: Metal sheathed electric cables
Inventor: GILL RONALD YAXLEY
IPC: B23K20/10
Filed: 1960-10-06
Abstract: 926,740. Making electric cables; welding by pressure. STANDARD TELEPHONES & CABLES Ltd. Aug. 16, 1961 [Oct. 6, 1960], No. 34294/60. Classes 83 (2) and 83 (4). [Also in Group XXVI] In sheathing an electric cable, a metal strip is folded round the cable with its longitudinal edges bent away from the cable and these bent away portions are passed between two pressure rollers which impart vibratory energy to the portions to effect a line weld therein. A strip of aluminium 3, Fig. 1, fed from a reel 4 is folded round a cable 1 fed from a reel 2 by a roller or die tool 5 so that the edges 6, 7, Fig. 5, are bent away from the cable. The edges are passed through an ultrasonic welding device 8 which forms a line weld 10, Fig. 5, and the welded edges are folded down on to the sheath by rollers 11, 12 with the weld beyond the bend. A machine 16 regulated by a capacitance measuring device 18 extrudes an outer thermoplastic sheathing over the aluminium. The sheathed cable is drawn by caterpillar capstans 13, 15. The welding device comprises a heavy roller 20, Fig. 2, in a bracket 21 urging it mechanically or hydraulically towards a second roller 19 formed on the end of a rod 36 attached to an electro mechanical transducer 22 by a plate 23 secured to a casing 24 having a support bolt 25 rotatably mounted in a bracket 26. Electrical energy is supplied to the transducer through slip rings 28 and collected by brushes 30. A bracket 37 has backing rollers 38 engaging the casing, the bracket 37 and bracket 26 being carried on a plate 39. The edges 6, 7 passed between the rollers cause them to rotate and the transducer, fed with radio frequency energy, causes the roller 19 to vibrate in a direction parallel to the edges and perpendicular to their direction of movement. Several sheaths may be provided, the pairs of welded edges being spaced from one another. A further pair of pressure rollers 44, Fig. 1, may be provided to form a slight deformation below the weld so that the edges may be firstly bent about the deformation before being bent on to the sheath. The strip may be transversely corrugated by meshing rollers 46 before being folded round the cable with the corrugated edges interlocked. Alternatively the edges may be left uncorrugated. A cotton, fibre glass, plastic or metal filament 47, Fig. 1, may be wound round the cable before the strip is applied and/or a filament 49, Fig. 1, may be wound over the sheath. Instead of a filament a polythene or aluminium strip formed with one or more ridges may be used. A cotton, fibre glass, aluminium, nylon, polythene or rubber filament 54, Fig. 14, may be fed from a reel 55, Fig. 1, against the sheath just before the edges 6, 7 are folded on to the sheath. To provide an electrical screen one or more metal strips may be helically or longitudinally applied to the sheathed cable e.g. an open corrugated sheath with flat edges is folded about the sheathed cable with a gap between the edges to expose the folded welded edges. The edges of the outer sheath may be locked in a folded seam or located diametrically opposite the folded welded edges.