Optimization Of Key Control Model In Tandem Cold Rolling Process

Customized production process of cold strip rolling leads to more frequent switching of various specifications during the cold rolling process.In the unsteady rolling condition such as Flying Gauge Change,due to the insufficient precision of rolling model,production stability and product quality precision can not be guaranteed.In order to improve the stability of the unsteady rolling process and the control precision of the strip width,the rolling mathematical model and the width control strategy were studied.The main work of this paper is as follows:(1)Aiming at the rigid demand of products based on sales prospects of a 1450mm tandem cold rolling mill,the cold rolling production line is facing with the problems of increasing production types and smaller batch orders.In order to meet the requirements of small batch,customization and production by weigh in the cold rolling process,the In Coil Gauge Change(IGC)technology was firstly proposed on the basis of existing flying gauge change,and the software package for engineering practice was developed,which has already realized the application and popularization of the field.(2)In order to improve the rolling accuracy of the unsteady process,the rolling force model,longitudinal stiffness characteristic of rolling mill and the motor power model in cold strip rolling were optimized.Based on elastic-plastic finite element method,a high precision three-dimensional numerical simulation model for 6-high UCM mill was established.The relationship between the longitudinal stiffness characteristics and the intermediate roll shifting value was obtained.The rolling force model was optimized intelligently using the method of combining BP neural network with genetic algorithm,and the results show that the prediction error of rolling force is within±4.5%.In order to improve the accuracy of motor power calculation,a method based on theoretical model and power loss test was proposed to calculate the motor power,and the calculation error of the motor power model can be controlled within±5.0%.(3)In order to reach the high standards of width precision in cold rolling,using the actual process parameters,the 3D finite element model of strip width spread which is fit to actual production process was developed.Single factor rotation was used to study the effect of rolling parameters on strip width,including reduction rate,front tension,back tension,deformation resistance and friction coefficient.(4)The simulation experiment was carried out through orthogonal test of five factor and four level,and the influence of five factors on the wide spread was analyzed by extreme difference analysis.The results show that the reduction rate has the most obvious effect on the wide spread.On this basis,the mathematical model of the strip width spread influenced by different rolling process parameters was obtained.The results of this paper are very practical for the unsteady rolling process of the strip cold rolling mill.At present,some of the research results have been successfully applied to a 1450mm five stand tandem cold rolling mill,which plays a positive role in improving the control level of strip cold rolling in China.