Book Description

The aim of this study is to investigate the effects of finisher drawframe storage variables such as can-spring stiffness, sliver deposition rate and sliver coils position on the quality characteristics of the combed ring-spun yarn. The research design also includes the effect of sliver storage time on the quality of stored sliver and subsequently on roving and yarn produced on speedframe and ringframe respectively. The critical role of storage can-spring parameters on combed sliver, roving and yarn quality has been frequently discussed in spinning preparatory literature. However, a clear understanding of the nature of relationships, as mentioned above, is not yet well established by the previous works. So, there is a need to study the underlying factors at a deeper level that may provide further insight into ways to control ring yarn quality. Therefore, the present investigations were carried out to observe the effects of uncommon process parameters namely can-spring stiffness, delivery rate and sliver coils position at post comber drawing stage on sliver, roving and yarn quality when slivers were allowed to feed without any storage time and after 8 hours storage time. The research plan was developed by implementing a three factor three level Box-Behnken design of experiment. The effects of aforementioned variables were studied on combed yarn unevenness properties (U%, CVm % and Imperfections), tensile properties (yarn tenacity and breaking elongation) and S3 hairiness. The results showed that the effects of can-spring stiffness and sliver coils position are significant on yarn evenness, CVm%, imperfections, tenacity and S3 hairiness. However, the combed yarn quality parameters did not show any significant relationships with the post combing drawing delivery rate. It was observed that the combed yarn produced from bottom position sliver coils using older can-spring showed less even yarn with improved imperfection, having less strength and more hairiness. The combed yarn quality further deteriorates on allowing 8 hours of sliver storage time. It was found that the bottom sliver coils experience the highest compressive forces compared to other sliver coils position and adjacent sliver coils stickiness was observed which result in sliver stretching and failure at the time of processing on speedframe. Also, older can- spring of reduced spring stiffness result in buckling which leads to stored sliver contact with rough sidewalls caused weak & hairy sliver. The combed yarn samples produced from such storage cans leads to uneven yarn with more imperfections, weaker and hairy yarn structure. The contribution of sliver coils position was found highest followed by can-spring stiffness in deciding combed yarn quality parameters in the current study. However, the effect of finisher drawframe delivery speed on yarn quality parameters was found minimal. Apart from this, an attempt has been made to understand the effect of dynamics of the can-spring mechanism on combed sliver handling at the time of sliver deposition at drawframe through bond graph modeling approach. The behaviour of the can-spring used for combed sliver storage was found linear as expected. It was observed that bond graph modeling of can-spring mechanism provides us information on more states in a systematic and algorithmic manner compared to any other technique. Linear momentum, linear displacement of top plate, force experienced by the combed sliver and load versus displacement response of the mechanism was also studied. However, the more rigorous study is required to study the accurate dynamics of such precise systems because the force and the stresses experienced by the combed sliver are too low due to very low inter-fiber cohesion.