Mathematic model of convergent point for rotor-spun composite yarn spinning process

The structure and characteristics of the composite yarn depend mainly upon where and how the two strands of fiber or filament are combined and mixed.This study established a mathematical model for static rotor-spun composite yarn spinning process based on mechanical analysis of the filaments,staples during composite yarn forming.Using the static model,the coordinates of convergent point under different spinning parameters of cotton/polyester(58 tex/7.8 tex) composite yarn are calculated.The results demonstrate that the convergent point x mainly changes with the radius of the rotor,and y changes with the tension of the feeding filament.There are two yarn forming points during the spinning process,i.e.,the point of staple fibers twisted as yarn,and the point of the staple-fiber yarn twisted with filament as composite yarn.Therefore,technical difficulties in rotor-spun composite yarn spinning process can be explained theoretically with these findings.