Research And Application On Agc System For A Hot Tandem Rolling Mill

Under the background of AGC renovation for a 750mm 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) Analyzing the reason of the thickness deviation in hot rolling, indicate the factor affecting thickness fluctuation. Through analyzing the mill spring curve, the relationship between the thickness deviation and gap adjustment by using mill spring function is defined.2) Aim at the problem of the temperature fluctuation affecting thickness in rolling; using GM-AGC based on mill spring function eliminates thickness fluctuation in steady rolling. Therefore a smaller thickness deviation in one coil is achieved and the basis of MON-AGC application on final stand is well formed.3) As the gauge meter is installed behind the final stand for 3-5 meters, the MON-AGC is a pure lag system, especially in low speed rolling. Aiming at this, the closed loop thickness control system with SIMTH compensation MON-AGC is proposed. At this rate, not only the problem of oscillation brought by the pure lag system is solved, but also the system dynamic response and steady precision are considered.4) Based on the research of automatic gauge control algorithm, 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 hot rolling. The actual results and record curves indicate that the AGC system of hot strip mill runs steadily, and the exit thickness deviation is controlled within±50μm.The research results in the paper are useful to the automatic gauge control system of hot strip 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.