Research On Key Control Problems Of High Precision And High Speed Strip Cold Rolling Mill And Its Engineering Application

This paper focuses on the production demand of high-precision and high-speed plate and strip rolling mills,with the goal of improving product quality and production efficiency.Several key control problems affecting the thickness accuracy,such as roll eccentricity compensation control,decoupling control of thickness and tension,rolling force prediction model and rolling process optimization,were studied.The automatic control system of high precision and high speed single-stand reversing cold rolling mill has been developed,which can effectively improve the strip thickness precision and production efficiency.The main contents of this paper are as follows:(1)The problem of the roll eccentricity seriously affecting the thickness accuracy of plate and strip during cold rolling was studied.In the process of roll eccentricity signal detection,a new method of roll eccentricity detection combining sparse Fourier transform and iterative adaptive method was proposed,which can quickly and accurately detect each harmonic parameter of roll eccentricity signal,and then an accurate roll eccentricity model was established.In the process of roll eccentricity compensation control,a roll eccentricity compensation control strategy based on cascade structure multi-period repetitive control was proposed,which can quickly track multi-period eccentricity compensation signals and realize eccentricity compensation control.Simulation and engineering application verify the effectiveness of the proposed method.(2)The problem of the serious coupling of tension and thickness in the production process of the sin gle-stand reversible cold rolling mill was studied.Firstly,the multivariable coupling control model of the tension system and the thickness system of the reversible cold rolling mill was established.Based on this model,a decentralized robust control strategy was proposed,in which the coupling between tension and thickness was considered as a disturbance and a robust controller was designed by using a mixed sensitivity index in each independent subsystem.The robustness of each independent subsystem was guaranteed to achieve the goal of decoupling.Simulation and engineering application results show that the method has good decoupling effect and anti-interference performance.(3)On the basis of systematic research mechanism model,a prediction model of the friction coefficient considering the rolling distance of the roller was proposed.Combined with the deformation resistance model,a more accurate rolling force prediction model based on the mechanism model was given through calculation and comparison.Furthermore,the adaptive coefficient was added to the friction coefficient model and deformation resistance model,and the Nelder Mead simplex optimization algorithm was used to solve the established objective function to obtain the adaptive coefficient,which improves the accuracy of the rolling force prediction model.Finally,a rolling force prediction model based on improved PSO-BP neural network was studied.The results of engineering application prove the validity of several rolling force prediction models proposed in this paper.(4)According to the characteristics of the single-stand cold rolling mill,a multi-objective optimization model composed of energy consumption function and equal power margin function was designed.The artificial fish swarm algorithm was improved into a multi-objective optimization algorithm to obtain the optimal solution of the multi-objective optimization model,and the reduction ratio of each pass were obtained.The engineering application results show that the optimized rolling schedule can effectively improve the production efficiency on the basis of the same energy consumption.(5)In order to meet the requirements of high precision and high speed rolling production,the automatic control system of single-stand reversible cold rolling mill has been developed using a two-level architecture of process automation system and basic automation system.A large number of practical application results show that the automatic control system of single-stand reversible cold rolling mill developed based on the research content of this paper can effectively improve product quality,yield and production efficiency,and meet the requirements of high precision and high speed rolling production.