Study on the filament motion and joint forming mechanism in the pneumatic yarn splicing process

Abstract

Pneumatic yarn splicing is a complex process concerning the winding of multi-filaments in a spiral airflow field. In this study, the joint forming mechanism is revealed by experimental and numerical methods. The whole splicing process in a specific-design splicing device was captured by a high-speed camera. A renormalization-group k-[Formula: see text] turbulent model was also adopted to simulate the distribution of the airflow field in the mingling chamber. From experimental images and numerical results, the motion of the filament with one fixed-end and a joint forming mechanism was discussed in detail. It is found that different parts of a large aspect ratio filament present completely different behavior due to its flexibility. The free-end of the filament is wound around the opposite yarn under the impact of circumferential airflow. Meanwhile, the bending deformation occurs at the middle part of the filament owing to the strong impact of the injecting airflow, and then it is dragged toward the fixed-end of the filament by axial airflow to prevent the forming of a joint. It is believed that the initial overlapping length has a decisive role in the forming of the splice joint. A proper overlapping length is of benefit to achieve enough winding loops at the free-end of the filament to resist the dragging force exerted by axial airflow and obtain a successful splice subsequently. The splicing experiments with different overlapping length and inlet pressure were conducted to verify the correctness of this analysis.

A dynamic modeling approach to the moving filament during high-speed winding by absolute nodal coordinate formulation

“…Ozdemir and Baser 12 studied yarns in the fabric through theoretical modeling combined with high-speed camera experiments. Wu et al 13 conducted theoretical modeling and experimental observations around the process of pneumatic yarn splicing. Yin et al 14 proposed a new theoretical model of yarn dynamics in a generalized twisting system.…”

“…Wu et al. 13 conducted theoretical modeling and experimental observations around the process of pneumatic yarn splicing. Yin et al.…”