Research And Application Of Strip Shape Compensation Model And Bending Force Preset Model

High-quality automatic shape control is a goal which the cold rolling producers continuously pursues since long ago,while shape preset control is the premise of automatic shape control,the shape of various compensation models are auxiliary tools of strip shape control.This paper is based on the strip shape optimization project of 1450 tandem cold rolling mill in a certain company.Flatness control systems of six high tandem cold rolling mills have been thoroughly studied.Aiming at the defeats of the flatness detection control systems of tandem cold mill,the work roll thermal crown compensation model,shape roller wear compensation model,bending force-preset model,the strip deformation resistance compensation model,deflector roll bending compensation model and deflector roll wear compensation model have been analysed.Industrial experiments and field applications show that the model is established to improve the precision of strip roll and strip shape quality,and the main work is as follows:(1)Aiming at the uneven distribution of the convexity in the axial direction of the work roll,the internal stress distribution is not reasonable in the strip after rolled,which leads to the problem that the strip steel is torn off.The electromagnetic heating beam device is designed according to the eddy current principle to adjust dynamically work roll local perimeter convexity and reduce the residual stress inside the strip after rolled.The device is effectively integrated with the flatness control system to make the flatness measurement closer to the set value.The experimental results show the device can effectively reduce the unreasonable internal stress distribution of strip.The purpose of improving control accuracy and shape quality is achieved to meet the shape control requirements of rolling mil.(2)According to the measuring ring wear of flatness measuring roll leads to shape measurement accuracy decline,in order to improve the measurement accuracy of flatness measuring roll,based on the theory of definite integral and Achard's theorem,the compensation control model of the measuring rings wear thickness of the flatness measuring roll is established.The deviation between the actual wear depth of the measuring ring and the calculated wear depth is given.The accuracy of measuring rings wear compensation model of flatness measuring roll is verified,and this model will be added to the flatness target curve.Measuring rings wear compensation model can be proved to improve indirectly the quality of strip shape and accuracy of shape detection by three types of strip.(3)Aiming at the problem that the precision of the bending roll force model is low,the shape quality of the strip head and the adjustment time are affected.The genetic algorithm and BP neural network algorithm are combined to overcome the dependence of BP neural network search on gradient information,and a high precision GA-BP neural network optimization model was established to predict the bending force of tandem cold rolling mill.Field application shows that the optimization model of GA-BP neural network can solve the problems such as over-long adjust time and out of tolerance of strip head because of lager deviation between bending force preset and stabilization bending force.(4)Aiming at the problem that the thickness of the strip at the head and tail of the rolling mill is too poor in the process of rolling speed reduction and variable specification speed reduction,various factors affecting the deformation resistance are analyzed,the influence model of deformation temperature and deformation speed on the deformation resistance is established,and the feasibility and reliability of the model are verified by different grades of strip steel.finally,The experimental results show that the influence model of deformation speed on the deformation resistance is added to the rolling force model which effectively solves the problem that the head and tail of the strip steel are too poor in the process of rolling speed reduction,and that roll speed and the yield of the strip steel are improved(5)In the shape measurement process,aiming at the flexural deformation of deflector roll and roll surface wear of deflector roll have an influence on the accuracy of steel plate shape detection.By studying the principle of flatness detection of ABB flatness measuring roll,based on the theory of simple supported beam,the theory of fixed integral and the theory of friction and wear,the deflection compensation model and the roll surface wear compensation model of deflector roll are established,respectively.Comparing actual wear depth values and calculated values of steering rollers,the accuracy of the roll surface wear compensation model and the practicability of the deflection deformation of the steering roller are verified by field actual production,and two compensation models will be added to the flatness target curve,respectively.The compensation model can be proved to improve measurement accuracy and shape quality by different types of strip shape.