Numerical simulation of dynamic pressures on a novel drafting system and experimental study on yarn properties based on friction fields

Abstract

The friction fields of a novel drafting device based on the ring spinning frame are investigated in terms of numerical simulation and experimental studies. In numerical simulation, the results demonstrate that the dynamic pressure distribution in the drafting zone is presented in the form of wave undulation in the main drafting zone. Besides this, the pressure peak greatly increases close to the front nip. The effect of different spacers and middle roller speeds on the pressure distribution was also simulated, which indicates that the dynamic pressure decreases strictly with increasing spacer size, while at middle roller speeds of 0.18 rad/s and 0.26 rad/s the pressure distributions only show a significant difference at the pins nip and not throughout the drafting zone. For experimental studies, the friction fields of the novel drafting device were tested with different spacers. The peaks of the friction field decrease with the increasing spacing in the main drafting zone. The friction force shows a wavy undulation in the direction of the middle roller nip to the front roller nip, and there is also a great increase in the peak of the friction force near the front roller nip. Analysis of the properties of the three yarns spun by the novel draft device under different spacers shows that changing the spacer affects the friction forces of the drafting zone and has a significant effect on the yarn evenness, imperfections, and strength, but not on the hairiness.