Analysis of sliver thickness variation from process perturbations in roller drafting

摘要

In processing fiber bundles in staple yarn manufacturing, the bundles are doubled and attenuated to an appropriate thickness via drafting. The process conditions are optimized with respect to the fiber and bundle properties. Otherwise, the output fiber bundle becomes non-uniform in its linear density. This research deals with finding the changes in linear density of the output bundle when perturbations are applied to the drafting conditions. Perturbations with specific autocorrelation functions were generated by the random phase spectral method. Along with the stochastically generated test signals, the transient linear density profiles of the fiber bundle in the drafting zone were simulated by using a mathematical model describing the dynamics of the roller drafting, and thus, the linear density of the output bundle could be predicted. Our results showed that the disturbances in input linear density affected the transient profiles of the linear density of the fiber bundle inside the draft zone. It was also shown that the output irregularities were strongly influenced by the perturbation in the input bundle thickness. During drafting, the perturbations in the draft ratio perturbations were not shown to have influenced the transient profiles of the bundle linear density inside the draft zone. However, the variation in the linear density appeared again in the output bundle following exactly the changes in the daft ratio. Disturbances in the process speed, however, were not shown to have influenced the output variation.