GB964909A - Improvements in or relating to the crimping and setting of textile strands - Google Patents

Abstract

964, 909. Crimping fibres and yarns. BRITISH NYLON SPINNERS Ltd. June 17, 1963 [July 19, 1962], No. 27713/62. Heading D1F. In a process for crimping textile strands, e.g. polyacrylonitrile, polyamide, polyester, polypropylene yarns or tows, in a stuffer-box, the back pressure exerted on a strand at the successive instants of crimping is maintained constant by a continuous and automatic control thereof effective at a point between the crimping point and the point (generally at or near the discharge point) of initiation of pressure on the strand within the stuffer-box. The compression chamber may be divided to form crimping and setting zone endportions which are relatively movable over a limited distance to effect the control (see also Specification 964,910). As shown, yarns Y converged at a guide 9 are fed around a loaded roller 11 into nip rolls 1, 2, driven at an adjustable constant speed from endless belts 3, 4, through pulleys 5, 6, and gear-box 7. Rolls 1, 2, form the entry to the crimping portion which is also bounded by walls 17, 19, and 21, 22, with extensions 23, 24, leading into the mouth of the setting portion comprising a chamber 25 enclosed by a heater jacket 27. This portion is urged towards contact with the crimping portion by a weight 31 and is mounted on flexible arms 28 and 29 which permit limited movement sufficient to control correctively the pressure on the yarn within the crimping portion i.e. at the point where the yarn is discharged from the nip of rolls 1, 2. The temperature e.g. 140‹C.-180‹C., in chamber 25 may be maintained by electrical resistance heaters 41, 42, and the crimp is set by dry or wet heat. The back pressure within the stuffer-box is initiated by restriction e.g. a hinged, adjustable flap 37 or converging walls (not shown) at the discharge end of chamber 25 (but the cross-sectional area thereof need not be reduced) and crimped yarn is withdrawn around a pin 45. The limited movement of the setting portion may be utilized to activate means (not shown) for varying the rate or amount of feed or withdrawal of yarn &c. to or from the stuffer-box so that the amount of yarn therein is maintained constant: thus, the arms 28, 29, may operate microswitches which energize a tensioning device to regulate the tension in the discharged yarn.