Bar Design for Length Compensation in Textile Winding

Abstract

In winding textile and other threads onto bobbins, the process of forming the wind by taking the point of take-up to and fro across the bobbin introduces length variations. These cause corresponding tension variations in the thread, which persist in the wound bobbin and which, in extreme cases, lead to breakage of individual fibers or the entire thread. These length variations are often compensated passively by a shaped bar, which should ideally maintain constant path length during the wind. A new theory is presented for designing the shape of the bar, and path length and tension variations are introduced at the edges of the bobbin where the cross motion reverses. Complete compensation for these effects is not possible using such a bar. The discussion is limited to cases of parallel bobbins as opposed to conical ones.