Research On Elongation Control System Of Cold Rolling Temper Mill

Temper is a final critical process in ensuring the finished quality of cold rolling strip. As only deformation target, elongation has utmost importance in ensuring interior structure property of strip to meet the requirements of user. In this thesis, the principle of elongation control system of cold rolling temper mill and methods of elongation control are introduced firstly, and then the practical elongation control system is designed. By analyzing of application of this system, some problems effecting on accuracy of elongation control are present. According to these problems, the mainly studies in this thesis are given as follows:1. Improving the precision of the prediction of tamper rolling force. Traditional theoretical formulas of rolling force is simplified and deduced under properties of rolling process and many assumptions. So it is difficult to compute the rolling force accurately. Because of its unique ability to process information, the technology of neural networks is very appropriate for the computing of rolling force. According to the theories of cold rolling and the theories of wavelet neural networks, a mathematical model of rolling force based on wavelet neural networks is founded. After the studying and testing of this model using practical production data, the fact is that the maximum error is below 6 percent. It's better than the maximum error of traditional rolling force formula, which is more than 30 percent. The accuracy of the model is fit for engineering application.2. Studying on new control strategies of elongation control system. At present, PID cascade control is widely used in the elongation control system of cold rolling temper mill. Because of the complexity of rolling process and various of disturbance factors, traditional PID cascade control can't satisfy the performance requirement. According to theories of predictive functional control (PFC) and the characters of cold rolling temper mill, PFC-PID cascade elongation control system is designed. Simulation results show that the elongation control system adopted PFC-PID cascade control strategy has more favorable dynamic characteristics than the system with PID cascade control strategy, and has good robustness and disturbance...