Numerical Simulation Of Thick Asymmetric Deformation And Control Research On Head Bending Of Medium Plates

Medium plates are important basic raw materials,which are widely used in various fields related to the national economy construction.With the continuous development of economy,new and higher requirements have been also put forward for the steel industry.The problem of head bending of the medium plates not only causes the cutting of the plate and affects the yield rate,but also damages the production equipment and affect the production efficiency in severe cases.But the problem of the head bending of the medium plates is still widespread in major steel mills and has not been completely solved at present.Therefore,this paper focused on the thick-direction asymmetric deformation during the process of rolling and aimed at solving the problem of the head bending of the medium plates.On the basis of systematically reviewing the relevant literatures on head bending of the medium plates,the effects of the reduction ratio and the shape parameters of the deformation zone on the head bending when the rolling line was misaligned were studied by numerical simulation,and the effect of the roll speed ratio on the head bending was studied.Finally,the head bending control method was explored by simulating the actual rolling process on site.The main contents and results of this paper are as follows:(1)The finite element model of the thick-direction asymmetric rolling process of the medium plates was established by using the finite element software DEFORM.The influence of the reduction ratio on the bending curvature of the head of the rolling piece was studied when the rolling line was misaligned.It was found that the effect of the reduction ratio on the bending curvature of the head bending was nonlinear and the relationship between the bending curvature and the reduction rate was approximately sinusoidal.Based on this influence law,the rolling reduction procedure of the final pass of the finish rolling in domestic steel mills was adjusted,and an optimization scheme was proposed,which provided a reference for the formulation of the process parameters of the head bending control.(2)The effects of the incoming material on the critical reduction ratio were studied by numerical simulation when the rolling line was misaligned.The results show that the critical reduction ratio was linearly increasing when the thickness of the incoming material increased.And a mathematical model of the critical reduction ratio and the thickness of the incoming material was established.Based on this mathematical model,the shape parameters of the deformation zone corresponding to the critical reduction rate were futher calculated.It was found that the parameters of the deformation zone under different incoming thicknesses were around 1.1,indicating that l/h=1.1 could be used as a basis for judging the state of head bending of the rolling piece.(3)Based on the actual production environment of site,the effect of the speed ratio of the upper and lower rolls on the state of the head bending was studied by numerical simulation.It was found that the rolling piece did not always bend to the slow roll side,and the change of the reduction ratio could cause a sudden change in the bending direction of the rolling piece.The relationship between the bending direction of the head and the forward slip value of the upper and lower surfaces of the rolling piece was analyzed.The results show that the bending direction of the head bending is related to the forward slip value on the fast roll side.When the forward slip value on the fast roll side is negative,the rolling piece bends toward the slow roll side;When the forward slip value on the fast roll side is positive,the rolling piece bends toward the fast roll side.(4)Aiming at a 3000mm plate mill production line in a domestic steel mill,the influence law of roll speed ratio on head bending was obtained by simulating the actual rolling process on site and the adjustment range of the roll speed ratio was determined,which provided a guidance for on-site production.According to feedback from field staff,good control results were obtained.