Model-Based Winding Tension Profile to Minimize Radial Stress in a Flexible Substrate in a Roll-to-Roll Web Transporting System

In this study, we propose a model-based taper tension profile that minimizes residual and radial stresses. In contrast to the constant torque and hyperbolic taper profile, the developed model can accurately decrease the winding tension depending upon the final decrement set by a user regardless of the maximum wound radius. Moreover, the model steeply decreases the winding tension in comparison to other tension models in the early stage, consequently, decreasing the residual stress and maximum radial stress. A hybrid model that combines the developed and conventional taper tension models is developed to expand the range of application of the model. A winding tension maker that applies the model to the winding tension controller is also developed. A variable transformation model that transforms the input of the developed model (radius ratio) to the winding time, which can be easily obtained without any sensors, is obtained. The developed model and winding tension maker are applied to an industrial roll-to-roll thin film winding machine. It is observed that local deformation in a wound thin film generated by the excessive radial stress is improved. A control technique is selected considering film characteristics, and a winding tension controller is designed using the developed tension models and winding tension maker. The designed winding tension controller decreases the maximum radial stress by 38% when compared to the case before application. Moreover, the winding length with few local deformations increases from 100 to 500 m; this confirms the superiority of the developed model and controller.