Patent GB-871112-A (GB)
Title: Process and apparatus for twisting filamentary material
IPC: D02G1/04
Filed: 1957-07-16
Abstract: 871,112. Spinning and finishing yarns; twisttubes &c. DU PONT DE NEMOURS & CO., E. I. July 16, 1957 [July 16, 1956], No. 22575/57. Classes 120(2) and 120(3) A travelling filamentary material e.g. continuous filament or staple fibre or tow, roving or yarn thereof, is twisted or false-twisted e.g. to form or crimp yarn, at least 50,000 turns per minute by introducing it axially into a passageway, having an equivalent diameter i.e. the diameter of a circle having the same area as the cross-section of the passageway, of 0À002-0À125 inch, into which one or more gas streams having at least half some velocity is/are directed in a non-axial direction against the periphery and eccentrically to the axis of the material while the latter is at a tension not exceeding 25 grams, the ratio of the cross-sectional area of the passageway to that of the gas stream(s) being from 4:1 to 1:10 (the areas being measured at the intersection of gas and material). The twisting action may be " direct " i.e. in the direction and caused by a cranking action of the fluid flow around the passageway and/or "indirect" i.e. in the opposite direction caused by frictional engagement with the wall of the passageway around which the yarn is rolled by the fluid flow. In the production of a permanent crimp, the feed rate of the material exceeds the take-up rate by 5-50%, a portion of twisted material between fixed feed and take-up positions is plasticized e.g. by heat or solutions of chemical agents, deplasticized to set the twist and then enters the passageway whereby it is back-twisted. If the material is a roving or yarn of staple fibres, the twisted ends may be so whipped about that the product is a " sheaf" yarn having lengths of parallel fibres separated at random intervals by shorter lengths in which ends of fibres are twisted tightly about the circumference of the yarn. If the tension on a yarn is randomly or regularly varied or the gas stream enters the passageway in turn through two or more conduits that direct the gas against the material in opposing directions, yarns having alternate lengths of ' S ' and ' Z ' twist can be obtained. The material produced may be combined with a second filamentary material that is at lower tension and/or travels at lower speed to produce a slub yarn (in which each slub has both 'S' and 'Z' twist) and/or cored yarn. The material may be subjected to a drawing operation before, during or after the twisting, and the combined treatment may directly follow the spinning of synthetic fibre material. The gas e.g. compressed air at room temperature, heated or refrigerated, or carbon dioxide, nitrogen or steam, may have an acceptable, or the desired, platicizing action on the material. After impinging against the periphery of the material, the gas may be directed along the axial length thereof to effect a forwarding and/or retarding, as well as twisting, action. Adhesive and/or size may be applied to the material before entry to the twister and plasticization. The material may comprise natural e.g. cotton, silk or wool, or synthetic e.g. regenerated cellulose, cellulose ester, polyacrylonitrile, polyamide, polyethylene terephthalate, or protein, fibre. Yarns of different form and/or materials, which will therefore develop differential properties of retraction when treated by the fluid twister, may be doubled before or after such treatment. In the fluid twisters, the passageway may be integral with or spaced apart from the gas conduit. The axis of the conduit may lie in a plane perpendicular to the longitudinal axis of the passageway or in a plane inclined up to 75 degrees from such perpendicular. A number of conduits and outlets therefor may be disposed longitudinally of and/or circumferentially about the passageway and directed in similar or opposed sense and lying in similar, parallel or different planes with respect to the passageway axis. Figs. 1-31 (not shown) illustrate forms of passageway, conduits and outlets and their manner of interruption, including passages which are asymmetrical, of varying cross-section, eccentric to each other, of hinged, divided construction with string-up slots (Fig. 16) and providing alternating air supply (Fig. 22). In a crimping process, Fig. 32, yarn from a package 75 passes through a guide 76, tension gate 77 (which may be vibrated to vary the yarn tension) or feed roller (not shown), is plasticized by passage over a hot plate 78 or by infra-red, steam-tube or hot water heater (not shown), false-twisted in a fluid-twister 79 and quenched or set by exhaust gases therefrom, and advanced by rollers 80, 81 to be wound into a "backwindable" package 83. As shown in Fig. 33, undrawn yarn from a package 90 passes over pin 91, through feed rolls 92, about a snubbing pin 93 and around the larger circumference of a draw or step down roll 94 used in conjunction with canted separator rolls 95; thence through a plasticizing e.g. heating, zone 96 and a falsetwister 97, around the smaller circumference of roll 94, to a package 99. If pin 93 and the larger circumference of roll 94 are by-passed, the yarn may be drawn on a hot plate while in twisted condition to produce a bulky yarn having reduced crimp. A filament bundle emanating from a spinneret and in a plasticized state, Fig. 34 (not shown), may be converged, divided into two groups passing upon opposite sides of pin which serves as a twist-stop, and fed through a fluid twister; twist in the bundle between twister and pin is set as by cooling or evaporation. A variety of " effect " yarns e.g. " sheaf " and " alternate twist ", Figs. 39 and 40, may be produced by the apparatus shown in Fig. 35 wherein a roving from package 125 passes through a trumpet guide 126 and drafting rolls 127, optionally, over an applicator roll 128 revolving in a bath of adhesive or size solution, if required, through a heater 130 whereby it is plasticized, through a twister 131, and it is wound into a package 133. Yarn from a package 134 may be combined with the roving at the rolls 136. In the apparatus of Fig. 36, pieces of staple yarn are fed from a reservoir 145 to a yarn being subjected to direct (false) twisting or cranking between rolls 142 and 147 to form slub yarn, as shown in Fig. 37 or Fig. 41 according to the yarn tension conditions. If a continuous filament (instead of pieces 144) is fed under randomly varying tension conditions on to the yarn, either the yarn or the filament travelling at the lesser tension and/or speed, it is wrapped therearound or vice-versa to form single or layered slubs and produce yarn such as shown in Fig. 38. Specification 514,821 is referred to.