Adaptive control of web tension in a heat transfer section of a roll-to-roll manufacturing process line

In this paper, an adaptive controller for web tension in the heating/cooling section of a roll-to-roll (R2R) process line is developed. Heat transfer processes are widely employed in R2R machines that are used to perform processing operations, such as printing, coating, embossing, lamination, etc., on a moving flexible material (web) on rollers. Heat transfer processes induce thermal expansion/contraction of the flexible material during transport. Because web strain and material modulus are functions of temperature distribution in the web, web tension resulting from elastic strain is affected by heating/cooling of the web. To determine the temperature distribution in a moving web, a multilayer heat transfer model for composite webs is presented. A governing equation for web tension is developed by assuming the web to be elastic with the consideration of elastic modulus as a function of temperature. An adaptive controller is developed to control tension in a tension zone by considering the governing equations for web tension and velocity. To evaluate the performance of the adaptive tension controller, a simulation study is conducted by considering an embossing section of an industrial R2R process line. Results from these simulations are presented and discussed.