Experimental Verification of Non-Linear Behavior of Over-end Yarn Unwinding From Cylindrical Packages

Abstract

Over-end unwinding has been proved to be the most optimal process to transfer yarn from one package to another in order to improve the quality and the characteristics of subsequent processes like warping and weaving. It is the highly non-linear behavior of this unwinding process that the variation in the quality of the final product is found and if this behavior is not controlled, the variation becomes more pronounced. This non-linear behavior should be well understood to select the optimum process parameters for a given operation and subsequent processing. This research study is done to analyze the effects of various process parameters on the tension distribution and balloon profile and to experimentally validate the mathematical model set forth for predicting the behavior of over-end unwinding. The materials used for the experiments are Polyester multifilament yarns of different linear densities (70, 270 and 500 denier). The variables used for the study purpose are Unwinding Speed, Mass Linear Densities, Package Diameters, and Guide-eye Distances. Balloon images are captured using a high-speed camera and the images are synchronized with the tension readings. Since three levels of each variable are used, 81 numbers of tests are conducted. Accordingly, the influence of changes in variables as well as the direction of unwinding (front-to-back or back-to-front) is seen for the tension distribution and balloon profile. The results of the experiments are compared with the theoretical predictions. In agreement with the theory, increase in the balloon height causes increase in tension. Also, the reduction in balloon count is accompanied by the increase in tension. Highest possible tension is seen with single balloon formations. With the same balloon count, an increase in unwinding speed gives rise to increased tension.