A Study of One-Step Conversion of Continuous- Filament Rayon to Spun Yarn

Abstract

The character and sources of denier nonuniformities in "direct-spun" yarn were investigated, and the variations were shown to be of two distinct types: long-length variations (10-100 ft. long) that arise from nonrandom breaking of the continuous filaments; and short-length variations (1-3 ft. long) that arise from discontinuous drafting of the broken filaments. The long-length variations, the more important of the two from the standpoint of fabric appearance, were found to result from minor variations in the tow or spinning machine which were greatly magnified by the spinning operation. A simple modification of the direct spinner, known as the "angled, high-speed apron," was de veloped to control the breaking of the filaments over a short region near the input rolls. This simple change in the path and speed of the apron increased the average length of the broken fila ments; increased the strength, elongation, and long-length uniformity of the yarn; improved the appearance of the fabric; and made possible for the first time the production of uniform, fine-count, direct-spun yarns. In order to be effective, the speed of the angled apron had to exceed a critical value that was shown to depend upon the front-roll speed and the position of the apron within the ratch.