Patent GB-534842-A (GB)
Title: Improvements in or relating to the manufacture of air-space electric communication cables
IPC: H01B13/18
Filed: 1939-09-19
Abstract: 534,842. Electric cables. STANDARD TELEPHONES & CABLES, Ltd. Sept. 19, 1939, Nos. 26155 and 26156. Convention dates, Oct. 19, 1938, and Dec. 13, 1938. [Class 36] A machine for making air-spaced cables having conductors held in position within a surrounding screen by slotted insulating spacing members is described as applied to a four-core cable. Spacers are conveyed one at a time from a magazine into association with the conductors and mechanism is provided for forcing the conductors into their respective slots. Fig. 1 shows in elevation a mechanism for inserting the radially slit washers at spaced intervals along one wire, means for introducing the other three wires, and, on the right, four pressure rolls for forcing the wires into the slots. Fig. 3 shows in plan the continuation mechanism in which three taping machines wind on, respectively, two layers of paper, one of copper, and two of steel, the cable being drawn along and twisted under tension by the winding mechanism at the end. In Fig. 1, the spacers are drawn from a hopper 75 by rotation of an apertured rim, in which they are held by air suction until they come opposite to the end of, and are released into, a vibrated delivery tube, and thereafter tilted and delivered to spaces between the links of a carrier chain along the bottom of which one wire 35 runs. A revolving brush 190, or an air jet, spins the discs until one slot engages the wire 35. Any disc not properly engaging the wire will be above the normal level and will operate an electric circuit breaker to stop the machine. The uppermost wire 38 is then fed into the upper slot of the discs and pressed home by the roll 220, and thereafter the side wires 36 are forced into their slots by rolls 247, and, after passing a device to ensure that no spacer is missing, the assembled cable leaves the carrier chain and from this point is advanced by the pull of the twisting take-up mechanism, including the reel 381. Pressure rolls 285, 286, 287, which have micrometer adjustment, force the wires into the slots the required distance. In the taping mechanism, Fig. 3, for forcing the screen, three taping heads 300, 301, and 302 successively apply two overlapping paper tapes, one overlapping copper tape and two gapped steel tapes to the assembled wires and spacers. The winding and tensioning device comprises a reel 381, carried on a revolving cradle 375, and traversed thereon alternately from side to side as the cable is wound on. Tension is applied by driving the drum through a spring-cushion from a planet wheel mounted on the revolving cradle of which the sun wheel is connected to a brake drum. If the brake is off, the drum and sun wheel rotate on driving the cradle without transmitting motion to the take-up reel. On applying brake pressure the drive will be transmitted and tension regulated by the pressure. In a modified form of machine, Fig. 31, for inserting spacer discs, the four wires are fed in simultaneously through guides and pressed into the slots in the spacers while the cable is pulled by a step by step motion. Three cams are on one shaft. Cam 514 actuates a rack 538 rotating a member in which a plunger 550 slides, to take a spacer 39 from a stack and bring it into line with the centre of the pressure rolls 593, 594. Cam 515 actuates a rod to engage a projection on the plunger and to press it forward with the spacer held by suction on its end, to engage the wires in the slots, while the third cam 516 reciprocates a pair of members 602, 603 which alternately hold and advance the cable by the distance between two spacers.