In this paper, the irregularity of the sliver after stational drafting is theoretically studied. In stational drafting, the distribution of change point at which the fiber leading end changes from back roller to front roller speed, does not change with time. After this study, V (y, ∞), the relative variance of number of fiber leading ends present in the piece of drafted sliver of length y may be expressed by equations (3.33), (3.35), (3.37) and (3.39) for the four types of irregularity of ingoing sliver respectively.
Among these four equatione, (3.39) may be applied to the drafting of most of slivers. The other three equations may be applied only to the special cases. Where the irregularity of ingoing sliver, the draft ratio D and the distribution of change point are known, V (y, ∞) may be obtained from equation (3.39). Here, _??_ is the mean density of fiber leading end, a_i is the relative amplitude of variation with wave length λi, A (λ, D, σ) and α (λ, D, y) are coefficients smaller than 1 as shown in Figures 3 and 5.
From (3.39), it may be suggested that if the distribution of change point is stational and _??_ remains the same, the irregularity of drafted sliver diminishes as D and the width of the distribution of change point become larger.