Placing of threadline at start-up of in-line melt spinning, drawing and winding at high speeds, involves initial timed period at slower speed

摘要

At start-up the yarn is placed on the rollers (6,7,8,9) and wind-up (5) while running at reduced speed, e.g. 4000 to 5000 m/min. Starting from time (T1) the speed is increased to reach working speed, e.g. 5000 to over 8000 m/min, at time (T2) in such a way that the speed ratio between the wind-up (5) and the last roller pair (9) is kept between 0.9 and 1.1, e.g. 0.99. The increased ratio is maintained for a time at least equal to 0.6(T2 - T1). At time (T2) the relax ratio is reduced by 0.5 to 5% to reach the working relax ratio, e.g. 0.97. The draw ratios between rollers (6) and (7) as well as between (7) and (8) together with the relax ratio between (8) and (9) are kept constant. The speed is controlled from the wind-up speed (5) or from the speed of the last roller pair (9).