GB1015291A - - Google Patents

Abstract

1,015,291. Forming twisted strands of silvers, yarns &c. -COMMONWEALTH SCIENTIFIC AND INDUSTRIAL RESEARCH ORGANIZATION. Oct. 16,1962 [Oct. 19, 1961; Jan. 16,1962], No. 39136/62. Headings D1D,D1F and D1W. A process for forming stable twisted "threads" from at least two "strands" comprises twisting a strand so that it has repeated along its length alternate zones of opposite twist, and stabilizing the twist by converging the strand with another strand and allowing it partly to untwist and thereby to twist around that other strand. The process may be be applied to consolidate rovings or slivers of wool, cotton, jute, flax or synthetic fibres after drafting gilling or combing, or to form yarns of stable fibres or of mono-or multi-filament strands. One or more twisted strands may be combined with an untwisted strand to form a core yarn-for example a core of nylon filaments and a covering of cotton or wool fibres-two twisted strands may be combined to form a novel plied yarn, Figs. 11A, 12A, 13A (not shown), or more than two twisted strands may be combined either directly or perhaps by splitting two strand threads and recombining the strands. The intensity of twist, or length of twist zone, may vary from strand to strand, while the strands may be of different colours. In Fig. 2 (not shown) two rovings 1 are passed through an apron drafting mechanism 3, and optionally through a twist length compensating device 6, to a twisting device 8, and then to takeup rollers 14 which comprise a pair of plastics impregnated fabric spur gears each having a vshaped groove 15, Fig. 6 (not shown), cut to about their pitch circle diameter. The twisting device comprises a central disc 9 having on each side a part annular rubber surface, and side discs 10 each having on the surface adjacent disc 9 a complete rubber annulus, each roving only being twisted when the appropriate part annular ring is in contact with the corresponding side disc, but the back twist in the roving being allowed to pass through device 8 when the part annular ring is out of contact with the side disc. The part annular rings on the two sides of disc 9 may be completely out of phase, or only partly so. In a second embodiment, the Figs. 8 and 9 (not shown) the drafting unit is of the roller type, the twisting unit comprises two tubes 20, Fig.10, and the strand converging device a series of rollers. Each tube 20 comprises jaws 21 pivoted to rotating tube 24 and having adjustable weights 26 which through centrifugal forces cause the jaws to grip and twist the strand 5. Periodically, through cam device 22, 27 non-rotating inner tube 23 moves to the right (Fig. 10) to open the jaws and allow the back twisted roving to pass through unhampered. Other twisting devices, which may be used, include intermittent or reversing tubes; or tapes or hyperboloidal rollers suitable modified to give an intermittent twist; or vortex twisting tubes.