GB794411A - Improvements in or relating to wire ropes - Google Patents

Abstract

794,411. Drawing; altering physical structure. BRITISH ROPES, Ltd. Aug. 13, 1954 [Nov. 18, 1953], No. 31992/53. Class 83 (4). Steel wire ropes or strands thereof are subjected to plastic flow with uniform pressure all round as by drawing, rolling or swaging and to a predetermined elongation by applying back tension in order to obtain an increase in fatigue resistance. Stranded steel wires of circular section are drawn through dies, and reduced in cross-sectional area by 20-40 per cent, the individual wires changing from round to polygonal section to form strands, as described in Specification 794,412, [Group XXV]. A machine for drawing strands 1, Figs. 3, 3a, through a die 6 comprises a cradle 2 from which the wire is fed through a guide 3 and wrapped round a capstan wheel 4 and passes through a cooling bath 5 containing dry ice. The wire is drawn by a capstan 7 and after passing through a guide 8 is reeled on a take-up drum 9 by a traversing gear 9a. The drum 4 is braked by a friction brake 15 to apply backtension to the strand of from 12-35 per cent of the breaking load and initiate plastic flow as the strand runs into the die 6. The cradle 2 can be rotated to twist the wire by a power drive 16 and the reel braked by a friction brake 18. The die 6 is mounted on a swivelled die-holder 12 which is moved through a quadrant and worm 13, by a handle 12 to impart " kill " to the strand. Lubricant such as a highly-refined mineral oil is supplied from a tank 11 through a centrifugal pump 10. The die may be rotated at speeds of 4000-5000 r.p.m. to reduce the power required to draw the strands. Strands prepared by the method and of round, triangular, oval, &c. form may be formed into a rope over a core of plastic or other material which may contain a conductor and the completed rope may be drawn down through another die to bed the strands into the core. In other forms of drawing machines the drawing blocks preceding and following the die may be run at different speeds by variable speed motors in order to obtain the required back tension. In modifications the drawing die may be replaced by hardened steel rollers mounted in a chuck rotating about the axis of the work to reduce its section or it may be replaced by segmental swaging dies. The drawing dies may also be arranged in combination with a stranding machine, the traction being applied by the haul-off capstan and the back-tension applied by the individual wire bobbins. Alternatively where the die follows the haul-off capstan the traction is applied. by a second haul-off capstan, the back tension being controlled by the speed of the first capstan.