Jung Ho Lim  Jong S. Kim  You Huh

Vol. 55,  No. 6, pp. 415-424, Dec.  2018
10.12772/TSE.2018.55.415

linear density drawn sliver draw ratio drawing zone length length distribution two passes single pass periodic change CV%

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The behavioral characteristics of sliver linear density under roller drafting operation were investigated in this study. A theoretical model describing the dynamic behavior of the staples flowing in a single direction was applied. While the model parameters remained constant, the process parameters including draw ratio and roller distance were varied. Simulations of the dynamic behavior of the drawn sliver linear density showed that it was dependent on the process conditions, and the effects varied depending on the staple length distribution. For uniform length staples, the linear density of the drawn sliver showed periodic changes at a steady state when the drawing roller distance was long. For the short drawing zone, the drawn sliver exhibited a constant steady state linear density. Increasing the draw ratio caused the linear density to change periodically which resulted in an increase in the CV% of the drawn sliver linear density. For length distributed staples, the linear density was sensitive to the draw ratio. At a low draw ratio, for example, DR=4, the drawing zone length did not affect the sliver linear density, and a constant linear density was observed. However, at high draw ratios, for example, DR=12, the drawing zone length affected the linear density behavior of the drawn sliver, showing periodic changes in the steady state. Thus, high draw ratios and long drawing zones caused a drastic increase in the CV% of the quasi-steady state linear density. In general, the two passes of sliver in a drawing operation with low draw ratio resulted in improved properties, that is, a more even linear density of the drawn sliver than that obtained using single drawing pass with a high level draw ratio, which drastically increased the linear density.