Abstract:

The principles of yarn quality improvement of the double S curves soft drafting technology-logy (doubles S soft drafting) were analyzed from the perspective of devices. The same types of yarns were produced by ring spinning and double S soft drafting, respectively, and the yarn samples were measured and compared. Then the characteristics of yarns produced by soft drafting were summarized and the reasons were discussed. causes In conventional ring spinning, the surface speed difference between the upper and lower aprons caused friction and static electricity, which resulted in decrease of yarn quality. Howere, in the double S soft drafting system, the upper and lower aprons and bins were removed, and the yarn body was well controlled and drafted by the S-shaped plates, cruve pipes and lattice aprons. By using the ring spinning and doubles soft drafting technology respectively, the yarn of combed cotton/polyester(60/40) with fineness of 18.4tex was produced, and yarn evenness and defaults were tested. The data were analyzed using statistic factor variance analysis. The results show that double S soft drafting technology can clearly improve yarn evenness, and reduce the occurrence probability of neps, thin places and thick places per kilometer. Double S soft drafting is especially useful for reduction of thickness (+35%) defaults index. The reason is considered to lie in the facts that doouble S soft drafting technology can optimize the distribution of drafting area friction and shorten the length of floating zone, and thus performing more effective control on floating fibers.

Key words: double S curves soft drafting, ring spinning, yarn quality, yarn evenness