GB887325A - Improvements in yarn packages - Google Patents

Abstract

<PICT:0887325/IV (a)/1> <PICT:0887325/IV (a)/2> <PICT:0887325/IV (a)/3> <PICT:0887325/IV (a)/4> <PICT:0887325/IV (a)/5> A stable package of low, e.g. one turn per inch, twist polyamide yarn, in which the yarn has a residual shrinkage less than 7% and a shrinkage variation throughout the package less than 1%, is produced by partially relaxing a drawn yarn by 2-11% of its unrelaxed length, optionally setting the yarn whilst it is held at constant length, and winding on a cylindrical cardboard or like inexpensive disposable core at a tension between 0,05 and 0,35 grams per denier. A partial setting step may precede the relaxation which may be 6-10% or 2-6% after drawing pre-packaged or "as spun" yarn. The setting is not completed, i.e. the yarn should retain a measure of residual shrinkage so that, dependent on its ultimate use, it can be further set. As shown in Fig. 1, undrawn polyamide yarn 1 from package 2 passes successively in multiple wraps about driven and separator rolls 4 and 5, a snubbing pin 6 and draw or stretching and separator rolls 7 and 8, through a jacketed oven 9, several turns around relaxing and separator rolls 11 and 12, and is wound on to a twister package 16 by ring 14 and traveller 15 under tension controlled by the weight of the traveller or additional tensioning means (not shown). The oven 9 may provide dry or wet, e.g. steam, heat or it may be replaced by a flat, curved and/or grooved plate which the yarn contacts, or a liquid bath, e.g. of mineral oil or molten metal. Alternative apparatus for relaxing the yarn, Fig. 3, comprises a stepped draw roll 28 coacting with separator rolls 8, 18 and 19 to provide a path (arrowed) for the yarn. As shown in Fig. 4, undrawn yarn 1 from package 2 passes successively in multiple wraps around driven feed and separator rolls 4 and 5, a snubbing pin 6, draw and separator rolls 7 and 8, setting and separator rolls 9 and 10 (rotating at the same peripheral speed as roll 7), relaxing and separator rolls 11 and 12. The yarn is heated in zones b and c as by a dry oven or a steam chamber, Figs. 6 and 7 (not shown). Heat setting apparatus, Fig. 8 (which, in the assembly of apparatus of Fig. 4 obviates the need for rollers 9 and 10) may comprise an oven 22 having heat transfer media inlet 23 and a condensate outlet 24 and having idler rolls 25, 26, around which yarn is wrapped several times before returning to draw roll 7. In another modification, Fig. 9, yarn 1 drawn in snubbing contact with pin 6, passes in multiple wraps about portion 7 of draw roll 28 and separator roll 8, from portion 7 about idler rolls 25, 26 (being set in zone f) back to portion 7, traverses a steam jacket (not shown) in zone e, passes over roll 27, thence in multiple wraps around roll 30 and portion 29 of roll 28 whereby it is relaxed, and is wound as stabilized yarn. Steam jacket (in zone e), setting oven (in zone f) and rolls 25, 26, may be obviated by heat insulating the portion 7 from portion 29 and mounting it, with its separator roll, in an oven. The relaxing roll, as 11, is maintained at a lower temperature than other rolls. Specifications 461,236, 506,125, 536,177, 543,466 and U.S.A. Specifications 2,071,250, 2,130,948, 2,157,119, 2,307,846, 2,477,156 are referred to.