When the roving is stretched by the sudden change of external force, the weak ring on the roving is often drawn down, and the twist on the normal yarn is transferred to the detail part.
When the yarn is fed into the drafting area, the details are easy to produce the phenomenon of hard head due to the more twist, or can barely stretch, but the drafting efficiency fluctuates. At this time, some technologists often use the methods of enlarging the nip gauge, enlarging the draft and reducing the roving twist factor to eliminate the stiff ends. However, these methods are of great help to the yarn evenness, slub and hairiness. Moreover, even if the hard end is eliminated, the yarn stability index is not ideal due to the influence of drafting efficiency fluctuation.
On the spinning frame, the yarn arrangement should be reasonable. Especially for siro spinning products, the distance between the roving surface and the guide bar shall not be less than 3cm, and the guide bar shall be located at 1 / 3 of the bottom of the roving. In addition, when spinning high count, Siro and other roving products with light weight, attention should be paid to the selection of hanging spindle to ensure the stable unwinding tension of roving.
