Model Optimization And Simulation Software Development Of Flatness Control System For Cold Rolled Strip

With the continuous improvement of strip flatness quality requirements of the downstream users,the theory of strip flatness control and its related technologies have been paid more and more attention by researchers.Therefore,the flatness control technologies have been further developed.The control model is the soul of the control system.The precondition of realizing the high precision automatic flatness control is to have the accurate flatness control model and the flatness control strategy.In this paper,combined with the actual production situation,the research status of flatness control is deeply analyzed.As the key model of automatic flatness control system,the model of actuator efficiency factor is studied deeply.A hybrid modeling method combining rolling process data and 3D simulation is studied to improve the calculation accuracy and online adaptability of the efficiency factor.On this basis,the coordinated optimal control strategy and its optimal model between the flatness feedback control system and the flatness feedforward control system are studied and formulated to realize the global optimal allocation of the actuator between the two subsystems.O n the ba sis of the theoretical research on the calculation model of the efficiency factor and the optimization model of control strategy,a simulation software platform of flatness control system suitable for the actual flatness control process is developed.The e ffect observation,evaluation and parameter optimization of control model and control strategy are further completed through system simulation.Finally,the flatness control process of a 1450 mm five stand tandem cold rolling mill is used as the research object,the industrial application of the control model and control strategy has been completed.In this paper,theoretical research,numerical simulation and simulation analysis are used to carry out the above research work.The main research contents are as follows:(1)Because of the low accuracy of the efficiency factor calculation model and the poor adaptability to the changes of production conditions,an online optimization and output prediction method of the efficiency factor based on the measured dat a is proposed.First,the efficiency factor is calculated by finite element method as the experimental value of the model.In order to overcome the low accuracy of experimental value,a hybrid modeling method based on process data is introduced.Because of low accuracy of the measured data,the measured data are processed by sorting and variable weighting calculation to obtain the accurate measured data of the efficiency factor.After the data model is imported and optimized,the output prediction model is established to acquire the efficiency factor in the actual rolling process.(2)In the flatness control process,the work roll and the intermediate roll are required to participate in both feedback control and feedforward control,so a coordinated optimal control model of flatness feedforward and feedback based on double-layer optimization is proposed.In the first level of optimization,the global optimization model of the actuator optimal adjustment is established.The constrained optimization problem of the model is transformed into the unconstrained optimization problem by using the penalty function method and the new optimization model in the form of penalty function is constructed.In order to solve the new optimization model and acquire the optimal solution of the objective function quickly and accurately,the improved interior penalty function method is used to solve the optimization model.The optimal output of the flatness actuator in the feasible region is acquired.In the second level of optimization,the output distribution model of feedforward control and feedback control is established.The cooperative control of flatness feedforward and feedback is realized by the calculation results of distribution model.(3)Aiming at the problem of many flatness defects in rolling process,the flatness control system simulation software is developed to simulate the flatness defect control process.Firstly,the simulation software of flatness control system is developed by using the idea of modular design,which integrates the independently developed target curve setting system,actuator response system,sectional cooling control system and flatness defect representation system into the simulation software interface.On the basis of the main interface,the initial parameter setting window and flatness efficiency factor window are established.In the target curve module,different interference curves are added to simulate and analyze the control process of various flatness defects.Finally,the analysis results are displayed on the software interface.Through the analysis of the results,it is found that the software can simulate the actual rolling situation accurately and meet the needs of users.