抄録
The purpose of the present study is to simulate the effects of doubling and drafting upon sliver irregularity in two-zone drafting of the three-over-three roller system. Two types of slivers, i.e. random and optional slivers were considered. It is assumed that a random sliver is made from fibers of uniform staple length and fineness, and that the number of fiber ends in any short increment of the sliver obeys Poisson distribution. In contrast, it is assumed that the fiber ends in an optional sliver are distributed on the basis of the uniform random numbers ranging in value between 0 and 1. The effects of the number of doublings, total draft ratio, distribution of draft between the two drafting zones, and the maximum moving distance of the speed change point were calculated on a Y.H.P. 9825A personal computer. The results were as follows:
(1) When the maximum moving distance of the speed change point is 0, the coefficient of variation of a sliver before and after drafting remains unchanged regardless of the number of doublings, total draft ratio and draft distribution. It was found, however, that the drafting changes the power spectrum (Fourier analysis) of these slivers.
(2) When the maximum moving distance of the speed change point is not 0, the coefficient of variation of a sliver varies with the increase in this distance. The number of doublings, total draft ratio and draft distribution between the two drafting zones considerably influences the power spectrum (Fourier analysis) and the coefficient of variation of produced sliver. It was also found that there is an optimum draft distribution between the two drafting zones.
