CVC工作辊热辊型演变机理及其对板形的影响

Evolution mechanism of thermal profile of CVC work roll and its effect on plate shape

CVC技术是20世纪80年代出现的先进的板形控制技术,该技术通过轧机工作辊轴向横移获得所需辊缝凸度,从而控制出口带钢板形。热轧过程中CVC工作辊的热辊型变化对辊缝凸度影响显著,精确预报工作辊的热辊型对提高带钢板形控制精度和减小轧辊磨损有着重要的意义。以某厂1780 mm带钢热连轧生产线为研究对象,运用大型有限元分析软件ANSYS/LS-DYNA分别建立第4机架的工作辊三维热凸度有限元仿真模型和三维有限元轧制仿真模型。分析不同轧制时间、轧制速度、轧制间隙时间等轧制工艺对热辊型的影响。将不同轧制工艺下得到的热辊型代入到轧制仿真模型中,分析不同轧制工艺下的热辊型对带钢板形的影响。轧制初期工作辊热辊型发生明显变化,工作辊热凸度增加,带钢凸度降低,4000 s后工作辊热辊型达到稳定状态,带钢凸度不再变化;轧制速度对热辊型影响较小,在热凸度稳定后对板形影响较小;工作辊随着轧制间歇时间的增加,冷却时间增加,热膨胀量减小,导致带钢凸度增加;随着带钢宽度的增大,工作辊边部吸收热量增加,工作辊热辊型边部发生明显变化,带钢凸度增大。仿真结果表明,轧制时间、轧制间隙时间、带钢宽度对板形影响较大,轧制速度影响较小,研究成果能为现场轧辊原始辊型曲线设计和板形控制提供参考。

CVC technology is an advanced flatness control technique that emerged in the 1980s.This technique achieves the desired strip shape control by laterally shifting the working rolls'axes in the rolling mill.The lateral movement helps in obtaining the required convexity of the roll gap,thereby controlling the shape of the outgoing steel strip.During the hot rolling process,changes in the thermal roll profile of CVC working rolls significantly impact the convexity of the roll gap.Accurately predicting the thermal roll profile of the working rolls is crucial for enhancing the precision of strip shape control and reducing roll wear.Taking the 1780 mm hot continuous rolling production line of a factory as the research object,large-scale finite element analysis software ANSYS/LS-DYNA is used to establish the three-dimensional thermal crown finite element simulation model and the three-dimensional finite element rolling simulation model of the work roll at the fourth stand.The influence of different rolling parameters such as rolling time,rolling speed,and rolling gap time on the thermal crown of the work roll is analyzed.The thermal crown obtained under different rolling parameters is substituted into the rolling simulation model to analyze the influence of different rolling parameters on the strip shape.At the early stage of rolling,the thermal crown of the work roll changes significantly,and the thermal crown of the work roll increases,while the crown of the strip decreases.After 4000 s,the thermal crown of the work roll reaches a stable state,and the crown of the strip no longer changes.The rolling speed has a smaller impact on the thermal crown,and its impact on the strip shape is also smaller after the thermal crown becomes stable.As the rolling intermittent time increases,the cooling time increases and the thermal expansion decreases,leading to an increase in the crown of the strip.With the increase in strip width,the heat absorption at the edges of the work roll increases,and the thermal crown at the edges of the work roll changes significantly,leading to an increase in the crown of the strip.The simulation results show that rolling time,rolling interval time,and strip width have a greater impact on strip shape,while rolling speed has a smaller impact.The research results can provide references for on-site roll original crown curve design and strip shape control.