Study on the influence of drafting forms in front drafting zone of ring spinning frame on fiber motion and yarn quality

Double apron drafting is the general drafting form in the front zone of the ring spinning frame. In the double apron drafting system, the top apron and the bottom apron form an elastic tensor gauge, which can better control the movement of floating fibers and improve yarn quality. In order to investigate quantitatively the influence of the top apron and bottom apron on fiber movement and yarn quality in the double apron drafting system, the differences of fiber acceleration point distribution, yarn irregularity and yarn strength spun by double apron drafting, single apron drafting and simple roller drafting under different process conditions were compared. Compared with simple roller drafting, double apron drafting and single apron drafting can effectively control the fiber movement in the drafting zone. With the increase of fiber length, the difference between the distribution of fiber acceleration points obtained by double apron drafting and that obtained by single apron drafting gradually decreases. When the fiber length is greater than 32 mm, the difference is small. Besides, by analyzing the improvement rate of the top apron and bottom apron on yarn irregularity and yarn strength under different drafting settings, it was found that the overall improvement rate of the bottom apron on the yarn quality was higher than that of the top apron, especially for manmade fiber yarns. Even in some cases, the strength of viscose yarn spun by the single apron drafting process is higher than that of the double apron drafting process.