三線式ドラフトにおけるスライバむらの変化

A theoretical calculation is made to simulate the effect of drafting upon the sliver irregularities in two-zone drafting of the three-over-three roller system. Two-types of slivers, i.e. random sliver and optional sliver are considered. It is assumed that a sliver is made of fibers of uniform staple length and fineness, and that the number of fiber ends in any increment of a random sliver obeys the Poisson distribution. It is assumed, in contrast, that the fiber ends in an optional sliver are distributed on the basis of the normal random numbers ranging in value between 0 and 1. The effects of sliver count, staple fiber length, fineness of fiber, draft distribution between the two drafting zones, and the maximum moving distance and the distribution of the speed changing point are calculated on a Y.H.P 9825B personal computer. Furthermore, the purpose is to clarify the relation between the irregularities of supplied sliver and the irregulerities due to the movement of the speed changing point upon the irregularities of sliver after drafting. The results are as follow : <BR> (1) When the maximum moving distance of the speed changing point is 0, the number of fiber ends in every increment remains unchanged, but the thickness of the sliver is reduced by the drafting action. Therefore, it is found that the coefficient of variation of drafted sliver increases by the square root of the draft ratio.<BR> (2) When the maximum moving distance of the speed changing point is not 0, the sliver irregularities vary with the increase in this distance. The increase ratio of sliver irregularities decrease with the increase of the British count of sliver, fineness of fiber and staple fiber length. And the staple fiber length has the most strong influence on it. Furthermore, the coefficient of variation varies with the draft distribution and the moving condition of the speed changing point on the two drafting zones. It can be seen that there is an optimal draft distribution which makes the coeffient of variation minimum, and that the range of the first draft ratio is about 1.5-3. When the distribution of the moving distance is one and the same in each drafting zone, the difference between the maximum and the minimum of the coefficient of variation is the smallest one.<BR> (3) It is also found that the correlation between the irregularities of the supplied sliver and the irregularities due to the movement of the speed changing point is almost always a negative value on each drafting. On the first drafting and the second drafting in which the moving distance of the speed changing point is 0, those correlation are regarded as independent of each ather because of the small value (Max. -0.2). However, on the second drafting in which the moving distance of the speed changing point is not 0, the correlation is not regarded as independent because of the large varue (Max. -0.7).