Application of compound control strategy based on temperature fluctuation in hot tandem rolling AGC system

The advancement of rolling technology relies on robust technical support, while the current control level has entered a critical turning point. The control effect based on traditional control theories has approached its limit, and numerous key technical problems have not yet been completely resolved. Therefore, it is imperative to introduce brand-new control theories and methods to achieve leapfrog improvement in control performance. In the hot-rolled strip production process, the automatic gauge control of the finishing rolling process occupies a core position, and its control accuracy directly determines the quality and qualification rate of the finished strip. To address the influence of temperature fluctuations on the stability of the exit thickness of incoming materials and the positive feedback problem existing in the traditional gauge feedback control, a hardness feedforward control strategy is proposed. Taking the Ansteel 1700 ASP production line as the application object, the influence coefficients of load distribution on various process indicators are calculated and analyzed; meanwhile, based on the increment equations of thickness, rolling force and crown, the roll gap adjustment values of the F₃—F₆ stands are determined. In hot rolling field practice, the hardness feedforward control of the F₃ and F₄ stands and the hardness over-compensation control of the F₅ stand are successfully realized. In addition, a nonlinear PID control strategy is introduced into the monitoring AGC system, which features a wide parameter tuning range and strong engineering practicability. Statistical analysis of production data of different rolling specifications shows that after the implementation of the composite control strategy, the strip thickness accuracy is improved by approximately 1% compared with the original level, indicating that the control system has good prospects for popularization and application.