GB964908A - Improvements in or relating to the crimping of yarn - Google Patents

Abstract

964, 908. Spinning. BRITISH NYLON SPINNERS Ltd. July 23, 1962 [July 28, 1961], No. 27349/61. Headings DID and D1F. In a process for continuously crimping nylon or polyester yarn in a stuffer-box to and from which the yarn is forwarded and withdrawn at constant speeds, a variable tension is imparted to the withdrawn crimped yarn by a tensioning device located between (and separate from) the crimper and the means for withdrawing the yarn. The tension is dependent on the amount of yarn within the crimper and is varied to compensate for any changes in such amount as may be detected by a sensing member. The regulation may be effected by two set tensions-one higher, and the other lower, than the mean tension calculated to maintain the amount of yarn within the crimper constant. Tension may be imparted by an adjustable "gate", magnetic hysteresis brake, or by a pulley wheel connected to one side of a magnetic particle brake having two " settings" for its voltage supply, corresponding to high and low yarn tensions and having its other side held stationary. The sensing member may be a hinged flap movement of which, in response to changes in the amount of yarn in the crimper, actuates a microswitch which controls a solenoid operating the tensioner or correctively adjusts tension through a direct mechanical linkage: alternatively, means (not shown) depending on photo-electric or dielectric variation of electrical circuits may be employed. As shown in Fig. 1, yarn Y is fed by nip rolls 1 through a crimping chamber 3 and setting chamber 5 (heated by electrical resistances in an insulated jacket 7) and variation in the level of compressed yarn in chamber 5 operates an adjustable, weighted flap 9 to close or open a microswitch 15 and so energize or deenergize a solenoid 17 to adjust correctively a tensioner 19 through which passes yarn being withdrawn from chamber 5 by wind-up rollers 21. As shown in Fig. 2, variation in level of yarn in chamber 5 is sensed by a plunger 35 movement of which causes a flange 37 to operate an arm 39 of a' switch 15 controlling a solenoid 17 to correctively actuate a hysteresis tensioner 43. In a modification of the apparatus of Fig. 1, the chamber 5, with jacket 7 attached, is flexibly mounted for limited movement in its lengthwise direction relative to the fixed chamber 3 and movement of the chamber is used as the means, operative according to the required correction through a micro-switch which selects voltages from a two-tapping transformer and applies them via a rectifier to a magnetic particle brake, for controlling tension in the withdrawn yarn, Figs. 3 and 4 (not shown). Specifications 963, 710, 964,909 and 964, 910 are referred to.