GB1348831A - Method and apparatus for treating yarns - Google Patents

Abstract

1348831 Heat shrinking yarns ROSENKRANZ & CO GmbH 6 Aug 1971 [7 Aug 1970] 37084/71 Heading D1F A method of heat-shrinking yarn comprises passing the yarn in a looped path through a heating chamber, the descending and rising loop portions being not allowed to touch the chamber walls, and the quantity of yarn in the chamber being regulated by altering the relative speeds of feed and withdrawal rollers. The chamber may be heated by radiant heat, by superheated or saturated steam, by air at 100 to 250‹C, by water at 60 to 100‹C, or by mixtures thereof. The treatment may comprise, Fig. 1, feeding yarn 1 in the form of loop 9 through heating chamber 8. The chamber is heated by radiant heater 8', and the yarn is subject to suction via a channel 14 which serves several chambers. The shortening of the loop, due to shrinkage of the yarn, is sensed by light cell 18 which accelerates yarn feed device 5 to thereby maintain constant the loop length and the yarn quantity in the chamber. When the loop shortens cell 18 causes electromagnet 20 to press roller 21 between roller 6 of device 5 and roller 22, so allowing roller 22 to accelerate device 5. When the loop lengthens, cell 18 decelerates device 5. The chamber may be heated by steam, at a pressure of 0.1 to 1 atmospheres above atmospheric pressure, fed into the chamber top by a perforated annular tube (Fig. 4, not shown). The yarn may be fed into the chamber in a pipe in which it is entrained by hot fluid, and withdrawn in a pipe in which it may be bulked by steam or dried by hot air (Fig. 5, not shown). In an alternative method, Fig. 6, the yarn is fed with hot fluid from oscillating tube 58 and sucked against sieve 57. The quantity of material in the chamber is regulated by sensing the pressure in space 62 above suction channel 56. As the yarn begins to cover the sieve the pressure in space 62 falls, and at a pre-set pressure monitoring pressure regulator 65 accelerates yarn withdrawal device 65. The device is decelerated when the pressure in space 62 increases and the quantity of yarn on the sieve decreases. In a modification, Fig. 7, the yarn is deposited on a moving continuous perforated steel or plastics belt 74. If yarn accumulates in the chamber so that it is carried by the belt against lever 93, the lever is pivoted to close contacts 97 and accelerate withdrawal device 103. Yarn supply tube 85 is oscillated across the belt. In a further method (Fig. 3, not shown) the yarn loop bottom extends below the chamber and passes under a hook controlling a winding speed regulator.