An Analysis of Roll Wrap Formation

Abstract

Roll wraps occur frequently in spinning and processing continuous filament yams, and particularly in drawtwisting fully oriented yams. An analysis of roll wrap formation that agrees with experimental evidence shows that the following conditions must be met for a wrap to form: there must be a broken filament in the yam, the upstream section of the broken filament must separate from the main yam strand, the broken separated filament must directly contact the roll surface, and the forces acting on the broken filament at the roll surface must be distributed so that the filament is attracted to the roll and must be of sufficient magnitude and duration to induce one complete wrap. The forces acting on individual filaments in a multifilament threadline were analyzed, and the resultant force required for wrap formation was determined. Results from this analysis offer a reasonable explanation for the well-known roll wrapping behavior.