This article considers how to regulate the draft ratio to make drafted sliver most uniform by means of an automatic control device such as the Autoleveller made by Prince-Smith & Stells Ltd. After some theoretical studies, the authors have arrived at the following methods:
(1) Measure the thickness variation of ingoing sliver at the back nip point or at some other proper point before it passes the back nip point.
(2) If it is observed that a portion of ingoing sliver is thicker or thinner by α% than the mean thickness, then increase or decrease the draft ratio by α% when this thick or thin portion reaches the point
s+l/2(1+_??_) distant from the front nip point toward the back nip point. As to
s,
_??_ and _??_see the Summary and Conclusions.
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