Research And Application Of Gauge Control Strategy For Tandem Hot Mill

Under the background of AGC renovation for a 620 rnrn hot strip mill, the automatic gauge control system in hot rolling process is especially investigated. With the fundamental of hydraulic automatic gauge control system and advanced automatic control theory, an optimum automatic gauge control algorithm for hot strip rolling is given. With the algorithm, a realizable control system of AGC in project is developed. The application of site shown that, the automatic gauge control strategy of hot strip mill achieves a higher control precision. The main work and results are as follows:1)The automatic gauge control technologies and equipment at home and abroad are analyzed, Expound the principle of automatic gauge control technologies and it’s core status in Rolling automatic. Study the factor affecting thickness deviation and the automatic gauge control strategy of hot strip mill.2) Based on the process of automatic gauge control equipment requirements.the automatic gauge control system with high performance and response using SIEMENS PLC is developed, and hardware configuration and software structure of automatic gauge control system is given. Now,the automatic gauge control system is used in a 620mm hot rolling.3) The automatic gauge control strategy used in the project is introduced, in order to solve the temperature fluctuations on the impact of the rolling force. A detailed analysis is done for the feedforward AGC Control Strategy used in the project. Models to describe the relationship of exit thickness variation,entry thickness and hardness coefficient of strip are built. Principles of hardness coefficient feedforward AGC system, methods to calculate adjustment amount of roll gap for feedforward AGC and a method of measuring for the hardness coefficient feedforward AGC are expounded and the error existed in measuring strip thickness limited the effect of gauge meter AGC and the solution to the problem is proposed.Additionly,for the problem of the monitor is a pure lag system,introduce a Smith predictor based on the track of strip segment at the same time research on correlation between gauge meter AGC and monitor AGC.4)Based on the hydraulic gap control model, the article establishes monitoring AGC and Smith AGC. Matlab simulation is used to compare the control effects. The results show that Smith AGC is superior to conventional monitor AGC In this part, generalized predictive control theory is introduced to monitoring AGC system and author does a in-depth research. The monitoring AGC system is established, and then established conventional Smith predictor monitoring AGC and monitoring based on generalized predictive control AGC model are set up according to it. Making comparison of the two controlling results through Matlab Simulink,the result demonstrates that monitoring based on generalized predictive control AGC model has better robustness and the ability of anti-interference.The actual results and record curves indicate that the AGC system of hot strip mill runs steadily and the exit thickness deviation is accurate within ± 20 μm.The research results in the paper are useful to the automatic gauge control system of hot mill. They are practical and can be applied in similar Project. Additional,there is also a breakthrough in the method of automatic gauge control algorithm, and the optimum scheme applying for automatic gauge control system is obtained.