GB821023A - Improvements in the drafting of textile fibres - Google Patents

Abstract

821,023. Drafting textile fibres. LINEN INDUSTRY RESEARCH ASSOCIATION. April 3, 1956 [April 1, 1955], No. 9504/55. Class 120(2) Apparatus for controlling the drafting of fibrous slivers to reduce short period irregularities includes mechanism operative by variations in the drafting force on the slivers to vary the degree of draft on the sliver. Both pneumatic and mechanical gauging units are described. In one embodiment, Fig. 2, a pneumatic gauging unit 15 is connected to bellows 13 and to a source of compressed air. According to variations in the drafting force on a sliver, a back pressure is varied to expand or 'contract the bellows 13 causing a movable guide 10 to increase or decrease the length of the path taken by the sliver between the rollers 2, 3. A gauging unit, such as 15, may be placed in front of the guide 10 and stationary guides or rollers may also bear upon the sliver between the feed and drafting rollers. The gauging unit may be incorporated in the movable guide. In another embodiment, Fig. 4, the position and speed of the feed rollers is varied according to the pressure variations indicated by a pneumatic gauging unit, which indications cause a vane 60 to obstruct to a greater or lesser extent the flow of air between orifices 58, 59 resulting in movement of bellows 55 to alter the position of a lever 49 carrying feed rollers 47, 48. Since the feed rollers 47, 48 oscillate about a driving gear wheel 52, their speed varies with each movement. A mechanism for varying the speed of feed rollers driven by bevel gears without affecting the position of the rollers is described. Another pneumatic apparatus employs bellows to alter the pressure of control rollers located between the feed and drafting rollers. A mechanical form of this apparatus has a feeler rod 99, Fig. 8, on an arm pivoted at 95 that carries a roller 93 which bears against a roller 92 driven at a higher surface speed than the feed rollers. Fibre control arrangements such as aprons, fixed guides or rods, or positively driven rollers singly or in pairs may be included in the apparatus. The apparatus may be employed to introduce slubs or thick places into yarns by utilizing a valve such as 100, Fig. 2 or 101, Fig. 4, to cut off the supply of compressed air to reduce the length of the drafting reach. According to the Provisional Specification long period irregularities may be reduced, slubs may be produced by employing a standard yarn as a pattern, time delay devices may be incorporated, electrical or electronic units may be used for measuring thickness and stop mechanism may be employed to operate when irregularities become excessive. Specifications 656,135 and 716,370 are referred to in the Provisional Specification.