Patent GB-1128669-A (GB)
Title: Improvements relating to strand twisting
IPC: H01B13/02
Filed: 1966-03-01
Abstract: 1,128,669. Stranding cables. FUJIKURA CABLE WORKS Ltd. 1 March, 1966 [1 March, 1965], No. 8889/66. Heading H1A. In a process for stranding wires into a group which has lengths of alternate left and right handed lay, use is made of a cradle which supports two twisting heads, one at each end, that rotate in the same direction at the same constant speed. The cradle is mounted between two fixed heads a set distance apart with a fixed head adjacent a respective twisting head. Twisting of the wires in one direction occurs when the wires are passed in a bundle through the first fixed head and then the first twisting head, and twisting in the opposite direction occurs between the second twisting head and the second fixed head. A resultant positive or negative twist is produced by alternately and periodically switching the running speed of the wires between two different predetermined values each time the strands have advanced by a storing length equal to the distance along the strands between a point intermediate of the first fixed head and the first twisting head and a point intermediate of the second twisting head and the second fixed head, divided by an odd number. The figure shown illustrates the twisting of twenty wires firstly into five groups of four wires, each group having lengths of alternate lay, and then similarly combining the five groups into a composite cable having lengths of alternate lay. The wires 111, which may be insulated conductors, are led in groups from the outlet guiding device 204 of the supply stand 200 to a respective adhesive applying device 800 and into one of a vertical bank of cradles 300. The device 800 has an entrance die 803 in the applying head 801 that forms the first fixed head, and a guide pulley in the rotation shaft 310 of the cradle which is rotated in a constant direction at constant speed forms the first twisting head. Groups of storage pulleys 315, 316 in the cradle provide a store for the desired length of wire between the fixed heads. Each time this length of wire has passed through the cradle the running speed of the wires is abruptly changed from one of the predetermined values to the other by the speed changing device 600, so that the resultant of the second twisting of the wires between the guiding pulley in the rotation shaft 311 and the fixed guiding pulley 317 is left or right handed lay according to whether the running speed was increased or decreased at the previous change. The speed changing device 600 comprises a group of fixed pulleys 603 and a group of movable pulleys 604 whose reciprocating motion towards and away from the fixed pulleys is controlled by a cam, Figs. 11 and 12 (not shown). This arrangement produces a fixed higher running speed from the take-on pulley 602 when the pulleys are moving away from each other and a fixed lower speed when they approach each other, whilst allowing wire to be drawn from the device 600 by capstan 700 at a constant speed intermediate the two fixed running speeds. As shown, the five stranded groups are led to a second cradle 500 which is exactly similar to any one of the first cradles 302-306. Between the first and second cradles a device 400 composed of five pulleys is provided to ensure that the twist reversal points do not coincide with each other when the groups are collected into the final cable. From the capstan 700 the cable is wound on to a winding device 750. Each device of the apparatus is driven by means of a main shaft 901 connected to a motor 900, Fig. 8 (not shown), by means of gearing and belt arrangements. Supplementary speed-changing devices may be provided, for example, in front of the first cradles. A binding device 850 may be used to apply tape to the wire.