Analysis and control of hot-rolled strip crown for cold-rolled middle-wave control
ZHANG Qiang1, LI Hong-bo1, CHEN Gang2, ZHANG Jie1, ZHANG Peng-wu2, WANG Wu-zhou2
1. School of Mechanical Engineering, University of Science and Technology Beijing, Beijing 100083, China; 2. Baosteel Wuhan Iron and Steel Co., Ltd., Wuhan 430083, Hubei, China
Abstract：The middle-wave flatness defect happens during the production of electro-galvanizing steel in a cold rolling mill. It is found that the cold-rolled strip with middle-wave flatness defect is related to the hot-rolled strip crown after the industrial data tracking and analyzing. In order to obtain the relationship between the hot-rolled strip crown control status and the cold-rolled strip middle-wave flatness defect, he industrial hot-rolled strip crown was statistical analyzed. It was found that the C40 values of the hot-rolled strip which was led to the cold-rolled strip middle-wave flatness defect, ere over 50 μm. And the ratio of the over 50 μm C40 value was 44.07%. It is proposed that the larger C40 value of the hot-rolled strip was a major cause for cold-rolled middle-wave defects. The influence rule of the data processing and calculation process of the hot-rolled strip profile gauge on the measured crown value is analyzed afterwards. The online crown measured value and the off-line crown measured value by manual measurement are compared. All the off-line crown measured values are larger than the online crown measured value, the difference is about 10 μm. So it is proposed that the error in the data processing process of the hot-rolled strip profile gauge, which lead to the actual larger strip crown than the measured value, is another major cause for cold-rolled middle-wave. To solve the larger strip crown problem, and considered the production stability, the transient process, a "small crown" control strategy is propose and put into industrial practice. It changes the hot-rolled strip target crown from 50 μm to 30 μm, the crown of hot-rolled strip is effectively controlled. The real production data is counted respectively before and after the "small crown" control strategy put into industrial practice. The re-grading rate of cold-rolled strip due to the defects of middle wave is reduced from 4.46% to 0.68% per month, the industrial practice got a good result. The research result shows a research idea and practical experience for the coordination control for the strip profile in the hot and cold strip rolling process.
张强, 李洪波, 陈刚, 张杰, 张鹏武, 王武洲. 针对冷轧中间浪的热轧带钢凸度分析与控制[J]. 钢铁, 2023, 58(2): 90-95.
ZHANG Qiang, LI Hong-bo, CHEN Gang, ZHANG Jie, ZHANG Peng-wu, WANG Wu-zhou. Analysis and control of hot-rolled strip crown for cold-rolled middle-wave control[J]. Iron and Steel, 2023, 58(2): 90-95.
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2023, Vol. 58 
