Research On Looper Tension Control Of Cold Rolled Strip Based On Sliding Mode Variable Structure

Looper is an important part of the cold-rolled strip steel production line and the nexus role of it is the key to achieve continuous production. Whether it could meet the technical equirements of the looper control can directly relate to the operation of the entire cold-rolled strip production line. The stable tension in the continuous production process is the basic to prevent the strip deviation and ensure the quality of strip products and the tension of looper strip also needs to maintain stable. Therefore, it is an important measure to ensure smooth production and the production quality that control the tension of the cold-rolled strip looper precisely and effectively.In this paper, the background is the galvanized production line and the study object is vertical entry looper. The thesis analyzes the basic control requirements of the looper and the basic principles and methods of looper tension control. As the control process of cold-rolled strip looper is relatively complex including a variety of working conditions which are divided into steady-state phase and dynamic phase generally and the tension control process of the two kinds of phases is very different. So a new looper tension control system is designed to make the looper work with different control mode in the two kinds of phases and optimize the control process. It is needed to fill looper and release looper frequently in the production process of cold-rolled strip. The dynamic process is different and the control requirement is different too. Then the system parameters will be changed frequently. Therefore, the thesis uses the sliding mode variable structure control which has strong robustness to the system parameter variations to design looper tension controller in the dynamic phase. To solve the chattering problem of the sliding mode variable structure control, tension roller is used to match up with the looper control to weaken the chattering phenomenon in the stage of sliding mode effectively. In the end, the rapid, accurate and stable tension control result is achieved.Finally, the author analyzes the control performance of the control system designed in the thesis by simulation. Compared with the performance of the conventional PID control, the sliding mode variable structure control system in this papter not only has better tracking and strong anti-disturbance performance but also can adapt to changes in parameters better and the effective control to the complex looper tension control system is realized.