Method and apparatus for imparting false twist to yarn before ring spinning

Abstract

A method and apparatus for imparting false twist to a short staple yarn delivered from a nip of a pair of front drafting rollers before ring spinning. Downstream of the nip, the twisted yarn is drawn sequentially across first and second runs of travelling endless belts, such that the yarn wraps about a first convex surface of the first run, then passes between the first and second runs, before wrapping about a second convex surface of the second run. Friction between each of the first and second convex surfaces and the yarn imparts the false twist in a common direction. Maintaining a differential between first and second linear speeds of the first and second runs, respectively, has been found to reduce yarn defects, particularly the nep count.

Description

TECHNICAL FIELD [0001]The present invention relates to yarn manufacture by ring spinning, and more particularly to a method and apparatus for imparting false twist to a yarn delivered from a nip of a pair of front drafting rollers immediately before imparting real twist by ring spinning.BACKGROUND OF THE INVENTION[0002]The characteristics of ring spun yarn are unmatched by the products of other yarn spinning techniques which may be more productive, so it is a technology that is unlikely to be superseded in the near term. Much research has gone into ring spinning technology and relatively modest improvements to the productivity of a ring spinning frame can be very significant in a spinning mill where many thousands of spindles are employed. Many different raw material and machine-related factors directly influence both productivity and quality, and sometimes improvements in one area have consequences that necessitate a trade-off in another area. The goal of spinning technologists mig...

AI Technical Summary

Benefits of technology

This patent provides a way to make things that are easy and effective to use, with fewer parts and a simple design that lowers manufacturing costs. This makes maintenance easier, too.

Problems solved by technology

However, it has been found that this single-belt technology results in an increase in yarn defects above the usual level—including the number of thick places, thin places and neps.

A sharp increase in the number of neps is of particular concern, since neps can be a cause of ends down in downstream processing and they may not take up dye like the rest of the yarn, detracting from the appearance of the fabric.

Achieving satisfactory nep counts therefore necessitates relatively higher maintenance costs to mitigate machine factors, such as wear, that are known to contribute to nep formation.

Images