基于喷气涡流复合空间力场内纤维耦合自捻的纱线增强机理

Jet vortex spinning uses a high speed rotating airflow under strong negative pressure instead of a mechanical rotating member to twist the free end fibers to form a yarn, which has the advantages of high speed and short process. The key scientific and technological problems that need to be solved urgently in its production are unstable twisting airflow and loose yarn structure，which result in the fiber drops and strength weak rings of yarn. The fiber self-twisting relying on the composite force of the additional friction field and the rotating airflow field in the jet vortex spinning twisting cavity can enhance the fiber cohesion in the yarn structure, then reduce the fiber being drawn by the airflow to form the fiber drop, and increase the difficulty of the yarn being stretched and broken. This project focuses on the study of the distribution intensity of the additional friction field and the motion law of the rotating airflow field in depth. The model of jet vortex composite space force field will be constructed to analyze the composite mechanical characteristics of the complex space force fields in the twisting cavity. A fiber/airflow coupled motion deformation model will be established based on the flow-flexible coupling mechanism formed by the mutual motion between the extremely thin and flexible fiber and high speed rotating airflow under strong negative pressure. It will reveal the free end fiber motion characteristics including scrolling, rotation and twisting during yarn spinning process by fiber coupled self-twisting under the combined action of fiber-airflow, fiber-hollow spindle support surface, fiber-fiber, etc. The purpose of this research is to clarify the yarn enhancement mechanism based on fiber coupled self-twisting and general process parameters controlling spinning stability. The work in this project will also provide theoretical basic for yarn component design and production practice guidance.

喷气涡流纺利用强负压高速旋转气流代替机械回转件加捻自由尾端纤维成纱，具有高速、短流程等优点。其生产中迫切需要解决的关键科技问题为气流加捻不稳定和成纱结构松散导致纺纱落纤及纱线强力弱环。依托喷气涡流纺加捻腔内附加摩擦力场和旋转气流场复合力学作用的纤维自捻成纱，可增强纱线结构中纤维抱合力，减少纤维被气流抽拔形成落纤的概率，增大纱线被拉伸断裂解体的难度。本项目深入研究附加摩擦力场分布强度与旋转气流场运动规律，构建喷气涡流复合空间力场模型，解析加捻腔内复杂空间力场的复合力学特征；研究极细且柔软纤维与强负压高速旋转气流相互运动影响而形成的流-柔耦合作用机制，建立纤维/气流耦合运动变形模型；揭示自由尾端纤维在纤维-气流、纤维-空心锭托持面、纤维-纤维等综合作用下滚动、自转和加捻的耦合自捻成纱规律。本研究旨在阐明纤维自捻成纱增强机理及调控其稳定性的普遍因素，为成纱元器件设计和生产实践指导提供理论基础。

喷气涡流纺利用强负压高速旋转气流代替机械回转件加捻自由尾端纤维成纱，具有高速、短流程等优点。其生产中迫切需要解决的关键科技问题为气流加捻不稳定和成纱结构松散导致纺纱落纤及纱线强力弱环。依托喷气涡流纺加捻腔内附加摩擦力场和旋转气流场复合力学作用的纤维自捻成纱，可增强纱线结构中纤维抱合力，减少纤维被气流抽拔形成落纤的概率，增大纱线被拉伸断裂解体的难度。本项目深入研究附加摩擦力场分布强度与旋转气流场运动规律，构建喷气涡流复合空间力场模型，解析加捻腔内复杂空间力场的复合力学特征；研究极细且柔软纤维与强负压高速旋转气流相互运动影响而形成的流-柔耦合作用机制，建立纤维/气流耦合运动变形模型；揭示自由尾端纤维在纤维-气流、纤维-空心锭托持面、纤维-纤维等综合作用下滚动、自转和加捻的耦合自捻成纱规律。研究发现：（1）槽体附近的气压值随着槽体走向与空心锭锥顶母线之间夹角的减小、槽体数量的增多而降低；（2）自由端纤维的运动轨迹在空心锭顶端0mm~5.25mm内，纤维轴线与空心锭顶母线之间所夹锐角α1≈53.5°，在5.25mm~11.15之间，纤维轴线与空心锭顶母线之间所夹锐角α2≈59.3°；（3）纤维在气流加捻过程中发生自捻的临界条件为 ，增加空心锭顶端壁面与自由端纤维之间的摩擦力，有利于纤维发生自捻，增大自捻纤维卷入纱体中的形变量；（4）随着自由端纤维滚动时间tmax的不同，最终卷绕到纱体中的形变量也会发生改变，当tmax<Tf, 最终卷绕到纱体中的自由端纤维形变量为 ，达到最大形变量 后，纤维绕空心锭壁面做纯滑动运动；（5）自捻型喷气涡流纺纱线断裂强力随断裂部分纤维根数的增多而增大，比传统型喷气涡流纺纱线强力提高了 ，其中 ≥0，且随着自捻纤维的形变量 增大而增大。本研究旨在阐明纤维自捻成纱增强机理及调控其稳定性的普遍因素，为成纱元器件设计和生产实践指导提供理论基础。