Study On 5-stand Tandem Cold Rolling Mill Thickness Control System

The gauge control is the main contents of tandem cold rolling mill control system. In order to reduce the length of strip near the weld that has excessive excursions in thickness, improve the thickness fluctuation of the cold rolling products and meet the user's increasingly server requirements for the cold rolled products, a great improvement on the automatic gauge control system has been made. A market effect of the control system not only need the sensors which can accurately measure various parameters of rolling process but also need the high-precision computing systems. The main contents of this paper as follows:Based on the 2030mm tandem cold rolling mill equipment of BaoGang, the author has studied on the automatic gauge control method, including the position of close-loop system, monitoring system, feed-forward control system, tension control and a variety of compensation. Combined with the actual situation, a perfect and high-precision gauge control system has been established, which has created favorable conditions for control system.There is fluctuates considerably in roll force and tension as the weld passes through the roll bite, which not only isn't conductive to the stability of rolling, but also affects the automatic gauge control. In this paper it is shown that a newly developed and highly successful technique which uses the state-dependent Riccati equation method for controlling tandem cold rolling mill system. State-dependent Riccati equation has the advantage of reducing the length of strip near the weld that has excessive excursions in thickness and reducing excursions in roll force and tension as the weld passes through the roll bite. State-dependent Riccati equation also can retain the mass flow balance in the mill to contribute to the stability of rolling. Finally, the controller has been simulated, the result of these simulations were included in the evaluation which showed successful control during the passage of the weld.SIMATIC STEP7 program software has been applied to accomplish hardware configuration, based on the requirements of rolling process technology. Then, compile the flow charts of preload, operational control and gauge control. In order to achieve the communication between S7-400 and Wincc, a PLC control system based on PROFIBUS has been set up. Finally, compile human-machine interactive interface by the use of Wincc. Ultimately, Siemens PLC S7-400 control system design and configuration have been finished, based on PROFIBUS Filed-Bus. The combination of PLC control system and Filed-bus ensure the system to be more reliable stable and effective. This will be a base to study in the future.