Design and application of an optimum backup roll contour configured with CVC work roll in hot strip mill

Abstract

CVC (Continuous Variable Crown) work roll contour technology since its invention has been applied in more than 150 hot rolling mills worldwide for controlling strip shape. However, serious uneven wear on backup rolls and even roll spalling problems can occur due to contact pressure concentrations that exist between work and backup rolls when either cylindrical or CVC backup rolls are configured with CVC work rolls. To prevent these defects, an optimized backup roll contour was designed by combining VCR (Variable Crown Backup Roll) and CVC backup roll contours. This solution features benefits of the VCR design - reducing roll stack deflection and equalizing contact pressure distribution between work and backup rolls - as well as increasing the control capability of work roll bending forces. Implementing the optimized backup roll contour eliminated non-uniform roll wear and spalling, and strip profile was also improved © 2012 ISIJ.