Analysis of the Unwind Section of an Industrial Web Processing Line

Abstract

The purpose of this thesis is to analyze the control strategies and tension performance of the unwind section of an industrial web processing line that manufactures composite flooring materials. The main elements of the unwind section of the web line include a torque controlled unwind roll, two driven rollers, an accumulator, and a dancer. Dynamic models describing the interaction and control of these web line elements are derived and used to generate improvements to the existing control strategies. The controller structures used are the Proportional-Integral-Derivative type. Experiments are conducted on the improved strategies for the unwind roll to verify their performance. A comparison between a torque controlled unwind roll and a velocity controlled unwind roll is performed. The basis of comparison is the stability regions in their corresponding controller parameter spaces. Comparing model simulation results and measured data verifies that the model adequately predicts trends measured in the unwind section. Model simulations and experimentation using the improved unwind roll strategies show improved tension regulation performance. However, it is seen that the variability and inconsistency in the braking mechanisms may limit the effectiveness of these improvements. Simulation results indicate that the modified control strategy for the first pull roll and accumulator also increased tension regulation performance. The analysis of the stability regions for the torque controlled unwind roll and velocity controlled unwind roll show that there is a greater flexibility in selecting the controller gains for the velocity controlled unwind.