A new computer geometric modelling approach of yarn structures for the conventional ring spinning process

摘要

A new computer modelling approach for three-dimensional yarn structures produced by the conventional ring spinning system is presented. The concept of virtual locations for modelling yarn cross section is extended. Virtual locations are ring configuration with ellipsoid shapes defined by yarn-twist level in each ring layer. A mathematical model based on migrating helix is developed. Fibre migration is governed by geometric and tension mechanisms. The migration parameters include twisting tension, migration period and amplitude. The initial phase and frequency of migration pattern are used as the parameters of fibre migration. Based on the results obtained from the virtual locations concept and mathematical model of twist, a computer-aided design modelling approach for fibre assemblies is presented for geometric and visual simulation of yarn structures. The fibre paths in each interval between two successive cross sections are approximated by non-uniform rational B-spline curves. The geometric model of each fibre is created by sweeping a closed curve along a centreline path. The new model is validated by using process parameters of spun rayon yarn.