Patent GB-848756-A (GB)
Title: Methods and apparatus for producing staple fibres
IPC: D01G1/02
Filed: 1957-01-24
Abstract: 848,756. Crimping, stapling and spinning yarns and filaments; yarn tensioners. DEERING MILLIKEN RESEARCH CORPORATION. Jan 24, 1957 [Jan. 24, 1956], No. 2642/57. Classes 120(2) and 120(3). Tow or yarn composed of continuous filaments of thermoplastic material e.g. polyamide, polyester, polyacrylonitrile, cellulose triacetate or acetate, is crimped by heat and passage under tension along a linear path having a curved portion providing an abrupt change of direction e.g. a sharp edge, and subsequently chopped into staple fibre lengths which, alone or in combination with different synthetic fibres or filaments or natural fibres such as cotton or wool, may be spun into bulky yarn and/or formed into woven or non-woven e.g. felt, fabrics. The crimp initially imparted may be partially latent i.e. the filaments are rendered potentially crimpable. and the full crimp developed, as by heat treatment, in one or more steps before stapling or at any stage of processing thereafter. As shown in Fig. 1, a yarn or tow (12-300,000 denier) of filaments 10, preferably in the form of a laterally-compressed ribbon, is led between rollers 12 and 14 under tension, over and in contact with an arcuate strip 22 which is heated by passage of electric current therethrough and passes over an acuate edge 25. The tension in the tow is regulated by means of a sensing roller 34 movement of which in response to a change in tension acts through an arm 35, rotatable collar 36 and arm 39 against the bias of an adjustable spring 31. to change correctively the position of a shoe 32 braking the roller 14. The filaments proceed through driven rollers 40, 42, which exert the tractive force pulling the filaments through the preceding apparatus, and are met by a "chopper" 50 into staple lengths 60. As shown in Fig. 2, filaments leaving the rollers 40a 42a pass through a hot air or heater box 70 wherein hot and, if necessary, moist air is blown across and through the tow in order to develop the crimp therein: crimped filaments are withdrawn by rollers 80, 82 which are driven at a peripheral speed which is so reduced in relation to the speed of the rollers 40a, 42a as to permit the shrinkage demanded by the crimp development, and are then stapled. In another modification, Fig. 3, the staple fibres leaving the chopper 50 (Fig. 1) are collected on the upper reach 92 of a conveyer belt 90 and are conveyed thereby through a steam or hot air box 96 from which the staple fibre emerges with the crimp therein fully developed. The first heating of the filaments may be effected by space or high frequency heating means and/or the strip 22 may be straight. The radius of curvature of the blade edge, the tension in the filaments as they pass thereover, the angles of approach and/or departure of the filaments with respect to the edge, the temperature of the heater element, the rate of cooling of the filaments after leaving the edge and the linear velocity of the tow may be varied between wide limits in order to modify the nature of the products. Lubricating agents e.g. low viscosity mineral oil, sorbitan trioleate, may be applied to the filaments.