Research On Tension Control System Of Cold-Rolled Vertical Looper

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.The working process of vertical loop is a complex, changeful process, especially during the dynamic phase, the looper tension system is a nonlinear, time-varying and uncertainty object. Therefore, it is an important measure to ensure smooth production and the quality of production, which controls the precision and efficiency of tension of the cold-rolled strip looper.In this thesis, the background is the leveling and recoiling line of Stainless Steel Co. 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 vertical 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. We need to fill looper and release looper frequently in the production process of cold-rolled strip. The dynamic and the control requirement process are both different as well as the system parameters will be changed frequently. The conventional PID controller is difficult to meet the higher control requirements. Therefore, the thesis introduces the sliding mode variable structure control which has strong robustness to deal with parameter variations of the system to design the looper tension controller in the dynamic phase. With analyzing the exponential reaching law, a new approach for the sliding mode control based on fuzzy reaching law is proposed in the thesis. 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. We finally make the tension control rapid, accurate and stable.At the end of the paper, we analyze the operating performance of the control system by simulation. Compared with the performance of three kinds of control methods, the sliding mode variable structure control system based on fuzzy reaching law in this paper not only has better tracking and strong anti-disturbance performance but also can better adapt to the parameters changes. In a word,we realize the effective control to the complex looper tension control system.