GB936284A - Improvements in or relating to crimping synthetic thermoplastic yarns - Google Patents

Abstract

936,284. Finishing yarns; roller arrangements. BRITISH NYLON SPINNERS Ltd. May 1, 1962 [May 19, 1961], No. 18251/61. Classes 120 (2) and 120 (3). In a crimping process, drawn or undrawn synthetic thermoplastic, e.g. nylon, polyester, polyacrylonitrile, polypropylene, polyethylene, multifilament yarn is squeezed between the nip of two cylindrical rollers, having smooth, e.g. polished or matt, surfaces of material harder than the material of the yarn, whilst the yarn is in a low-twisted (less than 10 turns per inch) state and at a temperature above 100‹ C. Undrawn yarn may also be stretched at the nip of the rollers. The yarn is then tensioned and back-twisted to zero twist or beyond to develop the crimp which may be enhanced by heating the yarn before and/or after backtwisting. Heat treatment or setting may be effected by passage of yarn through a radiant heater or contact with a heated metal plate: the same heating appliance may be used for treating the yarn both before and after crimping. The rollers may be heated and at least one is driven. The yarn product is free from torque and the crimp of the filaments is of regular " zig-zag " form with rounded apices. The crimp is planar over short lengths with adjacent short lengths differing, e.g. alternating, in respect of their planar orientation. The filaments in the supply yarn may be circular or non-circular in cross-section, but the former tend to be deformed by the crimping. Several yarn packages may feed the nip of one pair of rollers and crimped yarn may be wound separately or collectively into one or more hanks or packages or coiled into a container, in which forms the yarn may be heated, e.g. by steam. Three or more crimped and wound yarns may be plied, e.g. with doubling twist of two or three turns per inch in a direction opposed to the original twist in the yarns. In the apparatus shown in Fig. 1, yarn 1 drawn from a package 3 is guided around a tensioner 7, which imparts constant tension for the subsequent heating applied by contact of the travelling yarn with the curved surface of an electrically heated plate 9, the temperature of which is automatically maintained constant by a controller 11. The hot yarn is squeezed between driven nip-rolls 15, adjustably loaded by a press 17, and emerges as a flat ribbon which is tensioned, back-twisted and wound on a package 23 by ring-spinning apparatus. In a modification, Fig. 2, comprising rollers 35 and 37, blocks 39 bearing on the axle of the top roller are loaded by engagement of bifurcated rods 41 with arms 43 pivoted at 51 and weighted and counterweighted by weights 47 and 49. Hooks, as at 53, support the axle when roller 35 is removed.