Web tension behavior in the presence of eccentric rollers: Modeling and validation

Abstract

Since rotating machinery is used to transport the web on rollers, it is common to observe periodic oscillations in measured signals such as web tension and web transport speed. These periodic oscillations are more prevalent in the presence of non-ideal machine elements such as eccentric rollers and out-of-round material rolls. One of the main objectives in transport of webs is to maintain tension at a prescribed value. Tension regulation affects almost all key aspects of web transport including printing, registration, wrinkle formation, winding, etc. Therefore, models of web tension and web transport velocity in the presence of non-ideal rollers which can accurately predict measured behavior will be beneficial to the analysis of web transport under various dynamic conditions and in the design of suitable control systems.

The focus of this paper is on modeling the effect of eccentric rollers on web tension. The governing equations for web velocity on an eccentric roller and web tension in spans adjacent to the eccentric roller are presented and discussed. To solve these governing equations, one requires the knowledge of the entry and exit point of the web on the eccentric roller as it rotates and the length of web spans adjacent to the eccentric roller; a method in obtaining this information is described. To corroborate the models and the developed approach, data from experiments on a web platform are compared with model simulations and results are presented and discussed.