Influence Of Roll System Crossing On Strip Hot Rolling Process And Equipment

The rolling mill is the "mother machine" of strip production,and its spatial position accuracy and assembly accuracy directly affect the quality of the strip.However,with the accumulation of service time,the main components of the rolling mill wear and other reasons lead to the reduction of spatial accuracy,such as the moderate reduction of the rolling mill window,and the height difference between the two sides of the arch,which seriously affects the performance and rolling stability of the rolling mill.In order to meet the requirements of high-speed,high-precision and high-performance strip production,it is urgent to carry out research on the reasons for the misalignment of rolling mill space accuracy,the detection method and its impact on the rolling process and equipment.The roll system is the core component of the rolling mill.In order to increase the rolling stability,the work roll and the backup roll are usually set at 6～10mm offset along the rolling line direction,resulting in a huge contact pressure between the roll chock and the inner surface of the stand,coupled with the impact of rolling force and oxidative corrosion caused by biting and throwing steel,the rolling mill lining is subject to different degrees of wear during the working process.However,the online input of hydraulic AGC makes the longitudinal position of the rolls frequently adjusted,which intensifies the wear rate of the lining plate,which leads to the increase of the non-design gap of the rolling mill and the asymmetrical crossover phenomenon of the roll system.In order to systematically study the influence of the asymmetrical crossing of the roll system on the performance of the rolling mill and the rolling process,this paper based on a hot rolling mill in a factory,combined theoretical analysis and finite element simulation,and carried out the following work:The spatial position of the roll under the actual working condition is detected by the laser tracker,and the geometric correlation model between the wear amount of the liner and the intersection angle of the roll system is established according to the spatial geometric state of the liner,and the influence of the rolling mill assembly gap is considered.The cross angle range of the roll system under actual working conditions is determined.Based on this,the overall model of the strip mill was established by using the finite element software ABAQUS,and the influence of the cross angle of the roll system on the stiffness difference between the drive side and the operation side of the rolling mill was analyzed considering the work roll offset and the original roll profile.Through the finite element simulation of the strip rolling process,the effects of the roll cross angle,plate width and rolling speed on the lateral thickness difference of the strip,and the effect of the roll cross angle on the axial force of the rolls are analyzed.The results show that the asymmetrical crossing of the roll system has a serious impact on the rolling mill equipment and rolling process.Taking the lining plate of a 2 250 mm hot rolling mill in a steel mill as the object,combined with on-site sampling,the failure behavior and wear law of the lining plate were studied by means of friction and wear testing machine.And through the analysis of the macro-morphology and micro-structure of the wear area of the liner,the failure mechanism of the wear of the liner is summarized.On the basis of simulation data and experimental data,a prediction model of plate lining wear is established with reference to Archard wear theory.The predicted value of wear amount is in good agreement with the measured data of the factory,which proves the accuracy of the prediction model.The research work in this paper provides some theoretical guidance for the regular maintenance of hot rolling equipment and the optimization and adjustment of rolling process.