A new approach to improve the bulkiness of worsted grade wool yarn

摘要

In this research, attempts are made to apply an unconventional draft system to improve the bulkiness of worsted yarnnmade wholly from wool. The general concept of this research is focused on an uneven length distribution of wool fibersnand on the principle of the roller drafting system. Modification of the drafting system as well as various roller gaugenadjustments provides an appropriate condition to produce a yarn with different physical specifications. A traditionalnungrooved and smooth roller is used instead of the traditional grooved roller in the middle top roller of the draftingnsystem and the distance between the front and middle roller pairs of different gauges are adjusted to produce thensamples.nThe results of this research show that the yarn diameter and bulkiness strongly depend on the roller gauge of the draftingnsystem. The yarn produced with the ungrooved roller as the middle top roller of the drafting system shrinks more afternimmersing in hot water by comparison with the same yarn produced conventionally. The higher shrinkage of thenyarns results in higher lateral expansion and higher increases of yarn diameter and bulkiness. Other results shownthat, the ungrooved roller does not alter the yarn strength and irregularity. According to the results, the highestnvolume of the yarn produced with the ungrooved roller can be achieved at a gauge adjustment of 12.2 cm in whichnthe frequency of the fibers longer than the roller gauge in the staple diagram is about 8.4%. Consequently, the propernroller gauge of the drafting system should be determined from the staple diagram of the fibers and adjusted to obtainnabout 8.4% of fibers with a length of longer than the gauge.