Yarn Twisting Dynamics

In a spinning system, twist distribution throughout the yarn-forming zone determines not only the degree of twist in the final yarn, but also how a bundle of fibres evolves into a consolidated yarn. Yarn manufacturing and handling processes can be obstructed or aided by twist blockage. Knowledge of the principles of yarn twisting dynamics will enable researchers and other readers to understand the intricacies of these processes, to improve and innovate. This book presents a first principles approach to the solutions of yarn twisting problems in yarn manufacturing and handling systems.

Part 1 of the book derives the general differential equations of yarn twisting dynamics, describing rotational kinematics and kinetics, and the twist blocking mechanisms of travelling yarns in straight and spatial paths. General solutions to the yarn twisting dynamic equations, including twist wave propagation and twist distributions in idealized systems, are then presented. Yarn tensile, torsional and compressional properties are also discussed based on yarn helical structure models.

In Part 2, the yarn twisting dynamics and twist blockage theories are applied to different spinning systems, including conventional ring spinning, modified ring spinning, additive spinning (i.e., open-end spinning), constant and periodic false-twisting, rub-condensing (i.e., roving and slubbing production), false twist texturing and carbon nanotube yarn production systems. The influence of twist insertion methods on the structures and properties of final yarns is discussed based on the insights gained from solution of the yarn twisting dynamic equations.