Analysis of Thermal Expansion of Work Roll During Hot Strip Rolling Process

摘要

Thermal expansion of work roll is the key factor affecting strip profile and flatness during hot strip rolling process. On the basis of the energy conservation law, the two-dimensional temperature field and thermal expansion models of work roll were established with the finite difference method. To improve the computing precision of these models, boundary condtitons within rolling area, non-rolling area, shoulder, neck and end of work roll that agreed with the practice were constructed. The computed surface temperature and thermal crown of work roll were in good agreement with the measured values collected from a hot strip mill. The effect of strip width and work roll diameter on the thermal crown of work roll was studied. It is found that when the strip width changes from narrow to wide, thermal expansion at the middle of work roll changes little, while that at the edge of work roll increases greatly, thus making thermal crown of work roll decreased, and the thermal crown shape in the middle of work roll becomes flatness. It is also found that initially when work roll diameter increases from 450 mm to 750 mm, work roll thermal crown increases. Afterwards, when work roll diameter increases continously, work roll thermal crown decreases. It can be used to guiding strip profile and flatness control in hot strip rolling process.