THE ASPECTS OF TWIST ON THE FALSE TWIST DRAFTING

Abstract

In the previous papers, it has been shown that the drafting with false twister has the operation of levelling the sliver by twisting and elongation as well as the opration of collecting fibers for a sliver.
This report deals with the general and fundamental analysis of the twists given in the false twist drafting zone. A general equation was obtained for the variations in twists in the false twist zone. In a system of giving false twists at one place, the phenomena were theoretically analyzed (formula (5) and (9)) under conditions that the propagating speed of twists is much faster than the running speed of the sliver, and compared with the experimental results.
However, the false twist drafting such as in woollen ring spinning does not give twists at just one place but at two places of a twister tube, at the entrance and exit near a front nip. For such a system, formula (11), (13) and (15) are given.
The experimental results are as follows.
(1) The propagating speed of twists is much faster than the running speed of a sliver. This agrees closely with the assumption upon which the theoretical analysis is based.
(2) The test results on the variations in twists with the elapse of time agreed closely with the figures obtained by theoretical results in either case of giving twists at one place or at two places. (Fig. 3, 6, 9 and 10)
(3) In the case of twisting at one place, there are found twists in a zone between back rollers and a twister entrance in steady state, but no twists in the other zone between the twister entrance and a front nip. (Fig. 12) In the case of twisting at two places there are also twists in: a zone between the twister entrance and the front nip. In the case of actual woollen ring spinning there are more twists in the former zone than in the latter. (Fig. 13)
(4) Twists are given through the false twist friction between the tube and a sliver, and a considerable slipage can be observed. (Fig. 11)