Research On Tandem Cold Rolling Process Mathematical Models And Multi-Objective Optimization Strategy

In tandem cold rolling process,hot rolled steel strips are used as raw materials,which rolled by tandem cold mill at room temperature to obtain better mechanical properties and achieve the purpose of improving the strip surface finish and dimensional accuracy.Tandem cold rolling process control system is an important part of pickling coupled to a tandem mill computer-control system,and a significant means to ensure the yield and quality of cold rolled strip steel.Based on a upgrade project of 1450mm five-stand tandem cold mill electrical automation system,the study was carried out on the tandem cold rolling process control system and model specification system,including the intelligent optimization of mathematical models,model adaptation and load distribution and so on.On this basis,tandem cold rolling process control system was established and the research results were applied to on-line industry production,which had a better performance.The main works are as follows:(1)A cooperative adaptation algorithm of rolling force model and forward slip model based on objective function was proposed.Through establishing the cooperative adaptation objective function and the multi-population co-evolutionary algorithm was adopted to search the optimal solution.Simultaneously,the adaptation coefficients fulfilling the accuracy requirements of both rolling force model and forward slip model can be obtained,and the setting precision of rolling force and forward slip get obviously improved.(2)A tandem cold rolling thickness control model based on hardness identification was established,and at the same time,an improved thickness control strategy in consideration of flatness was proposed.The improved AGC eliminates the impact of the incoming strip hardness fluctuation on thickness and decreases flatness deviation effectively.(3)A rolling schedule multi-objective optimization algorithm for thin gauge strip rolling process was put forward.The flatness objective function was built based on influence function method and then a comprehensive multi-objective function based on power,tension,and flatness was built.The multi-objective function was solved by tabu search algorithm,and in order to increase computational efficiency,cut down computation time,the case-based reasoning technology was used to obtain the initial solution for searching process.The proposed multi-objective optimization algorithm improves the product quality and flatness under the condition of giving full play to the equipment.(4)A bending force presetting multi-objective function considering rolling force was established based on deviation of the roll gap crown,and an improved multi-objective intelligent optimization algorithm was adopted to solve the objective function in order to avoid the risk of iteration non-convergence.The optimized flatness presetting system runs stably and ensures the product flatness accuracy.(5)Tandem cold rolling process control system was established.The structure of process control system,functions of basic automation level and production management level were introduced.Process control human machine interface system and report management system were developed combining with the actual needs,and achieved good effect.(6)The results of this study were tested by industry experiments and the control effect of process control system was analyzed on the basis of measured data.Experimental results show that the control system works well and the strips of different kinds and specifications can obtain good control effect.The product dimensional accuracy is much better than that of target requirements.