Rieter

The operation of the combs

Index

The  circular combs can treat only the forward portion of the fiber fringe to be processed, since the comb clothings do not penetrate exactly to the bite of the nippers and also because the rear ends of the fibers are located within the nippers. The fairly long, trailing portion has therefore to be combed out by another device – the top comb – while being drawn through it (a passive process).

This could lead to the false impression that the trailing portion of the fringe is not processed as effectively as the front portion, because it is not passed through a complete combing zone (circular combs), but only through a single row of needles. In fact, the quality of processing of both portions is the same. This statement requires some explanation. Cleaning and elimination of short fibers is, of course, performed by the  top comb, but also at the same time by the retaining effect (self-cleaning effect) of the batt in the nippers. During detaching less than 20% of the fibers in the nippers are pulled out of the batt (Fig. 49). This low percentage of fibers is unable to take the impurities within the batt with it, because the retaining force of the more than 80% of fibers of the thick batt that remain is too strong. Impurities, neps, and short fibers therefore remain in the sheet as the other fibers are detached. It goes without saying that this retained material also has to be eliminated somehow, somewhere. It occurs when the fringe is treated by the circular comb during the next combing cycle, or the following one. Elimination is always performed by the circular comb.

The self-cleaning effect can be influenced by several factors, including the batt weight and the degree of parallelization of the fibers. Of course, the self-cleaning effect is better, the lower the parallelization of the fibers and the more voluminous the batt. Unfortunately, however, the latter entails overloading of the combs and very poor combing performance. As usual in spinning, the golden mean has to be found.

Fig. 49 – Self-cleaning effect of the batt