GB848798A - Improvements in the crimping of yarns - Google Patents

Abstract

<PICT:0848798/IV(a)/1> <PICT:0848798/IV(a)/2> In crimping yarn of staple fibres or continuous filaments of regenerated cellulose such as viscose, organic derivatives of cellulose such as cellulose acetate, or wholly synthetic materials such as polyhexamethylene adipamide, polyaminocaproic acid, polyaminotriazoles and polyethylene terephthalate, the yarn is drawn from source at one linear speed and forwarded at a higher linear speed to a zone (in which false-twist is imparted) so as to stretch the yarn by an extent which may exceed the elastic limit, immediately before it enters the zone. The stretching, e.g. 3-7 1/2 %, or 600% if also used to develop physical properties such as tensile strength in a synthetic material, may be effected when the yarn is cold or softened, as by heat. As shown in Fig. 1, yarn 5 from a package 6 passes through a guide 7, around two sets of stretching rollers 8, 9 and 11, 12, through a steam header 13 (which may be replaced by an electrically heated chamber) and a false-twisting device 17 and is wound, with controlled relaxation, into a package 22. In a modification, Fig. 2, yarn passes in contact with a heated surface 25 and, optionally, around a snubbing pin 26 which may be rotated with a peripheral speed less than that of roller 8. Two or more yarns may be stretched between rollers 8, 9 and 11, 12, combined with doubling twist in the false-twisting zone and then separately wound, Fig. 4 (not shown).