It is difficult to ensure ideal symmetric conditions during hot plate rolling, so rolled plates may bend upwards or downwards. The factors affecting the plate curvature are temperature difference, roll diameter difference, rolls speed mismatch, frictional difference, reduction rate, ingoing thickness, inclination angle, etc.
In the single strand mill, the difference in the height of the upper parts of the lower roll and the breast roll is fixed. So, during multi-pass rolling, the plate sometimes faces inclined entry. Reprocessing of the work roll also causes the difference in the roll diameter. Therefore, it is very important to determine the admissible roll diameter ratio that causes very narrow range of plate curvature for normal rolling.
Ri Chun Ho, a researcher at the Faculty of Materials Science and Technology, investigated the influence of the inclination angle of the plate on strip curvature during the 7 passes of reversing rougher at the hot mill when the plate enters with inclination, by using the three-dimension finite element analysis software, DEFORM-3D. Based on this, he determined the range of admissible roll diameter ratio that leads to the very narrow range of plate curvature when the plate enters with inclination.
He found that the roll diameter ratio of reprocessed work rolls is not allowed to exceed 1.067.
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