| 摘要 |
<p>PURPOSE:To improve product quality by imparting thickness larger than the difference between a thick part and a thin part in the final target thickness during rolling and thereby producing a tapered steel sheet superior in flatness. CONSTITUTION:A pass schedule is set up which imparts a thickness difference DELTAHm larger than the difference between the thick part and the thin part in the final target thickness by preliminarily tracing back from the final pass. Thickness forming is commenced at the thickness of H0 in the early stage of rolling, and rolling in multiple, e.g. (i) passes is performed so as to make the thickness constant in the longitudinal direction. Tapered rolling is commenced from the thickness H1 after (i) passes, and a thickness difference is imparted in steps toward (m) passes. Reduction is performed so that the thickness difference is DELTAHm between the thick part and the thin part at the (m)th pass. At this time, a thickness difference can be imparted which is larger than the difference DELTAHn between the thick part and the thin part in the final target thickness by making the reduction larger in the thin part compared with the thick part. After the completion of the (m)th pass, a constant control on a crown ratio is performed for bat thick part and thin part until the (n)th pass reaching the final target thickness.</p> |
