带钢热连轧工作辊温度场与热凸度的数值模拟

Numerical simulation of temperature field and thermal crown of work roll during hot strip rolling

采用轧辊表面边界逐一处理与等效处理两种方式,研究一个轧制周期内工作辊温度场及热凸度的变化规律,并对温度场的频域特性进行了探讨。根据热轧工作辊的实际边界条件,建立工作辊温度场的轴向对称差分模型,通过模拟结果与现场实测工作辊表面温度和热凸度的比较,验证模型的可靠性。结果表明:计算轧辊热凸度时,轧辊转动的复杂边界条件可用等效边界条件代替。轧辊温度场可分解为低频分量和高频分量,前者为主导因素,而后者仅影响轧辊表面10 mm以内的区域,称为"浅层效应"。离表面越近,温度变化越剧烈;离表面越远,温度达到稳态所需的时间越长。轧制初期轧辊热凸度呈现较快的指数上升趋势,轧制一定数量带钢后,热凸度趋于一个动态稳定值。

Using one-by-one and equivalent boundary condition processing on work roll surface,the evolution rule of temperature field and thermal crown of work roll in a rolling campaign was studied,and the frequency characteristic of roll temperature field was discussed.According to the actual boundary condition of work roll in hot strip mills,an axially symmetric finite difference model for roll temperature field was established.The simulation results were compared and verified with the measured values of roll surface temperature and thermal expansion after a rolling campaign.The results indicate that the complex boundary conditions of work roll rotation can be replaced by equivalent boundary conditions in the calculation of roll thermal crown.It is found that the roll temperature field can be decomposed into a low frequency component and a high frequency one.And the former is main factor,while the latter only affects the 10 mm region below roll surface,which is called shallow effect.The closer the region to the roll surface is,the larger the amplitude of roll temperature is,and the farther the region to the roll surface is,the longer the time of reaching steady state temperature is. The roll thermal crown initially increases exponentially,and tends to become a stable value after rolling a certain number of coils.