Study On Contact Friction Resistance Of Hot Rolling Work Roll During Online Shifting Process

As a key technology during the national steel "13th Five-Year Plan",endless rolling has been promoting China's steel industry to a direction of short process and green manufacturing.Online shifting of work rolls during hot rolling is one of characteristic techniques for the continuous rolling technologies,such as endless strip product(ESP).It has a big difference from the work roll shifting in the traditional hot-rolled process.The shift is the no-load traverse generated during the interval in traditional rolling line,and this paper mainly focus on the online shifting of the work roll under load.The online shifting of the work roll can effectively reduce the wear of the edge of the work roll,which is conducive to improving the shape quality of the steel sheet and prolonging the working life of the work roll.Therefore,it is possible to accurately predict the shifting resistance of the work roll during the automation set and profile control has important significance.In this paper,the friction resistance of the hot rolling work roll during the process of online shifting is studied through theoretical analysis and the finite element simulation.The variation law of the roll shifting resistance between the backup roll and the strip under of difference factors,such as rolling force,speed ratio and friction coefficient,has been investigated intensively.In the theoretical aspect,the calculation method of the shifting resistance between the work roll and the backup roll is deduced based on the pre-displacement-slide friction theory.The method of solving the limit pre-displacement is clarified.The contact area between the work roll and the backup roll is divided into Sliding area.The contact friction between work roll and strip is analyzed by sliding friction theory,and the formula for calculating the shifting resistance of work roll is deduced.The calculation method is simplified according to the corresponding simplified rules,making it easy to calculate.On the basis of the finite element simulation,different friction models were selected to simulate the contact friction between work roll and backup roll as well as the contact friction between work roll and strip.The results of the theoretical calculation between the work roll and the support roll are compared with the finite element simulation results.It is found that the shifting resistance of the roll increases linearly with the increase of rolling force and friction coefficient.With the change of the speed ratio in a certain range of linear distribution,more than a certain value after a non-linear distribution,and the theoretical results agree well with the numerical simulation results.Through the finite element simulation of the working roll and the strip,the variation law of the lateral friction,the width of the cross section in the contact arc length,the strip width were analyzed under different factors,and the change of the shifting resistance of the work roll is obtained law.The finite element results show that the shifting resistance of the work roll increases linearly with the increase of the shifting speed,and the linear decrease trend decreases with the increase or decrease of the temperature.