Effects of Rolling Conditions on Surface Brightness of Rolled Strips in Pair Cross Cold Rolling

摘要

Generally the surface brightness of a rolled strip decreases as the oil film thickness increases in cold rolling. Accordingly, the improvement of surface brightness has been difficult under rolling conditions that make the oil film thicker. Through basic investigations using a model Pair Cross mill, it is found that the surface brightness of a rolled strip can be greatly improved in cold rolling with slightly crossed rolls. As the cross angle increases, the number of microdefects (oil pits and marks transferred from the ground roll surface) on the surface of the cold-rolled strip decreases, even with the rollig speed of 800m/min. In cold cross rolling, a large diameter of the work roll is more effective for improving the surface brightness than a small diameter, in contrast to the case of normal rolling. This suggests that the transverse component of relative slip between strip and work roll in cross rolling has a significant influence on the improvement of surface brightness.