Novel curved roll contour technology for profile control in hot strip mills

Abstract

The combination of variable crown contour and work roll shifting is a prominent and efficient tool for strip profile and flatness control in hot strip mills. The design principle of variable crown contour has great influence on the control performance. In this paper, the development on variable crown contour is carried out in depth, and a novel curved work roll contour consisting of a piecewise smooth curve with quadratic parts is developed to make the relationship between crown adjustment capacity and strip width strictly linear in a certain width range. This characteristic enhances the crown adjustment capacity of mills, and makes them more powerful for profile control, especially for narrow strip. Meanwhile, the equivalent crown of work roll is linearly proportional to its shifting position, which will definitely facilitate the profile and flatness control system. Additionally, an optimisation model is proposed to find the optimal contour coefficient to decrease the axial force and diameter difference of work roll. Compared with some conventional curved contour technology which its crown adjustment capacity is proportional to the square of strip width, this novel contour has a stronger crown adjustment capacity for both wide and narrow strip, thus, promising to apply in hot strip mills to enhance the overall performance of mills in profile control. The industrial application of this new contour technology shows the percentage, which strip head crown is within 0·05±0·02 mm, is up to 95·6% after being used on the upstream stands of the hot stainless strip rolling mills.

Keywords:

• Hot strip mills
• Profile and flatness control
• Roll contour
• Work roll shifting
• Stainless steel

Acknowledgements

The theoretical research was supported by the Fundamental Research Funds for the Central Universities (FRF-TP-11-003A), the 2012 National Science and Technology Support Program (2012BAF09B04), the Program for New Century Excellent Talents in University (NCET-10-0223).