Numerical Analysis of Thermal Expansion of Rolls with Equivalent Heat Transfer Model on Circumference

摘要

In hot strip rolling, the work roll shift method has been widely used to disperse thermal crown and wear of the work rolls in the axial direction. This paper provides a strategic control method for the work roll profile which surpasses the conventional work roll shifting method. A numerical simulation model which enables prediction of thermal crown and wear of work rolls with high accuracy has been developed, and a new shifting method has been proposed, focusing on the problems of the conventional shifting method.In the conventional shifting method, the thermal crown within the contact area is calculated with a fixed cyclic stroke and step. In that case as the stroke increases, the average value of thermal crown in a rolling campaign decreases without concentration of heat input from the strip to the axial center of the work roll. However, as the stroke increases, the standard deviation of thermal crown during the campaign increases.Although the work roll shift method is effective for dispersing work roll thermal crown and wear, the thickness profile of the strip is affected by the positional relationship between the work roll and the strip. Therefore, for further improvement of the work roll shift method, the need for a flexible shift method which considers the positional relationship between the work rolls throughout the entire rolling campaign is suggested.