A tension control for web transportation in continuous annealing processes

This paper presents a mathematical model for web tension behavior and a tension regulation control scheme in a continuous annealing process (CAP) line. An annealing processes have widely variation of temperature on the web. This variation causes thermal strain. In addition, a vertical web transport system (WTS) for mass production causes gravity strain. Therefore, the conventional mathematical model for tension behaviors of a moving web is extended to the tension model considering thermal and gravity strains. In addition, the feed-forward velocity compensator for the web tension control is suggested, which is based on the proposed mathematical model with thermal and gravity effects. In order to evaluate the validity of the proposed mathematical model for a vertical WTS and the proposed web tension control system in a CAP, computer simulations that considered thermal and gravity effects were executed and an experiment was implemented.