Nonlinear Phenomenon in High-Speed Yarn Transport

The shape and tension distribution in yarn balloons in case of over-end unwinding of yarns from stationary cylindrical packages and in case of ring spinning are analyzed. Yarn motion in over-end unwinding is considered a three region problem: (1) from guide-eye to lift-off point on the package, (2) from lift-off to the unwind point on the package and, (3) from unwind-point to a point on the stationary coil where yarn tension equals the residual tension. The unwinding behavior appears to be strongly influenced by radius of the package (through the related air drag parameter) at the time of unwinding, yarn to package drag coefficient and residual tension in the yarn. Experimental programs are underway to validate predictions of the theoretical model as well as to measure parameters needed for the analytical model: to wit, air drag coefficient, yarn-to-package drag coefficient and residual tension. In the case of ring spinning, implications of the bifurcation phenomenon have been further studied theoretically. In particular, implication of a slub traveling through the balloon on the stability of the balloon has been explored in detail. Regions of stability and instability in parametric space have been elucidated. For uniform yarns, the influence of traveler mass on the stability of a free and controlled balloon have also been studied. Increase in traveler mass makes the spinning balloon generally stable (eliminates bifurcation largely) even though the spinning tension also increases. Experimental programs are underway to validate predictions of the theoretical model. Some preliminary results are reported.