Rieter

Noil extraction with forward feed

Index

After the detaching stage has been completed, all fibers longer than E have been carried away with the web. Since there is no feed step during the return stroke of the nippers, the fringe is presented to the circular combs with length E. During the following combing cycle all fibers shorter than E pass into the noil; this is represented in the staple diagram (Fig. 17) by the area qBr. Feed occurs during the subsequent forward stroke of the nippers, during which the fringe is increased in length by the distance S. At the next stage, that of detaching, the detaching rollers take at least all fibers longer than E (Fig. 16, fibers a) into the combed web. However, as feeding occurs at this stage, fibers b of the original length (E - S), i.e. shorter than E by the feed amount, are now moved forward to the nip line by feed through distance S. That is why fibers longer than (E - S) are now carried away into the combed web, and trapezium AmnC represents these fibers.

In this case also, the figure qmnr can be divided according to the mean fiber length by the line op (E - S/2), and thus the following relationship can be derived as before:

$p \% = \frac {oBp}{ABC} \times 100 = \frac {{(op)^2}}{{(AC)^2}} \times 100$$= \frac {{(E - \frac{S}{2})^2}}{{M^2}} \times 100$

From the two derived relationships it follows that where backward feed is used, noil is increased as the feed distance is increased, whereas in forward feed noil is reduced as the feed distance is increased.

Fig. 16 – Position of the nippers relative to the detaching rollers at the closest approach during forward feed

Fig. 17 – Combing out with forward feed (staple diagram).