带钢热连轧机工作辊非稳态传热的数值模拟

NUMERICAL SIMULATION ON UNSTEADY STATE HEAT TRASFER OF WORK ROLLS DURING CONTINUOUS HOT STRIP ROLLING

以Flunet 6.3为平台,利用多重坐标系和自定义函数功能,研究了3种常用复合轧辊在带钢热连轧过程中的非稳态温度波和热流波的传播特点,并对其引起的热冲击现象进行了探讨.结果表明,辊内的温度分布和传播特点可以分为高频和低频2种非稳态温度波来进行研究.高频温度波随着深度的增加快速衰减,最大影响深度不超过7.5 mm,而低频温度波衰减较慢,深度超过了20 mm.热冲击随着深度的增加而快速减小,在同样的条件下,高速钢复合轧辊的热冲击深度最大,而高Ni-Cr铸铁复合轧辊的热冲击深度最小.随着轧钢块数的增加,工作辊每轧制一块带坯的吸热量减少,散热量增加,留存的热量减少.

The spreading properties of unsteady state temperature wave,heating flux wave and heating shock phenomena during continuous hot slab rolling have been numerically simulated for three types of commonly used composite rolls by use of various coordinate systems and user-defined functions based on Fluent 6.3 software.The results indicate that the temperature wave can be divided into a high-frequency and low-frequency unsteady state temperature wave to describe the temperature distribution and spreading properties in rolls.It is found that the wave amplitude of the high-frequency temperature wave will quickly decrease with the increase of propagation depth,and its propagation depth of maximum impact is less than 7.5 mm.But,under the same rolling conditions,the amplitude attenuation of the low-frequency temperature wave is slower,and its propagation depth of impact is more than 20 mm.The heating shock decreases rapidly with the increase of distance from the surface of work roll.The heating shock depth is the deepest for the high speed steel composite roll,but the shallowest for the high nicked chromium cast iron composite roll under the same rolling conditions. The absorbed and resided heat by work-rolls during each slab hot rolling is down,but the dissipated heat by rolls is up with rolled slab number increasing.