Development of comprehensive treatment technology for strip C-shaped warp defect in galvanizing unit
QIAN Sheng1,2, GU Qing1, LI Xue-tong1,3, BAI Zhen-hua1,3
1. National Cold Rolling Strip Equipment and Process Engineering Technology Research Center, Yanshan University, Qinhuangdao 066004, Hebei, China; 2. College of Mechanical and Electrical Engineering, Huangshan University, Huangshan 245041, Anhui, China; 3. State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, Hebei, China
Abstract：In order to study the serious problem with uneven coating of hot-dip galvanizing strip steel products caused by C-shaped defects, continuous annealing process of hot-dip galvanizing units is optimized, and the comprehensive treatment technology of C-shaped defects of strip are developed. Firstly, the equipment and process characteristics of the continuous annealing process of hot dip galvanizing was considered, the formation mechanism of C-shaped warping was analyzed. The influencing factors such as the state of open burner, the state of the radiation tube, the state of the cooling fan, the gravity of the strip, and the genetic shape of the upstream process section were analyzed, which made the larger temperature difference on the surface of the strip, resulting in the uniform distribution of transverse residual plastic deformation of the strip in its thickness direction. When it exceeded its critical instability condition, C-shaped warping occurred. And then, from the perspective of systematics, the system function of continuous annealing furnace with the influencing factors of C-shaped warping defect was established. The multivariable coupling and complex nonlinear characteristics of continuous annealing furnace were considered, the continuous annealing process was divided into subsystems in the unit of process section, and the minimum warping of each process section was taken as the optimal goal. Based on C-shaped warping prediction model of the strip, the temperature optimization objective function of heating section, the temperature optimization objective function of soaking section and the optimization objective function of cooling fan state in cooling section were established respectively, and the system function was established in the form of the objective functions of each process section superposing. The comprehensive optimization method of process parameters in each process section of continuous annealing process was obtained, and the optimization process was formulated. The key technologies such as temperature optimization setting technology in heating section, temperature optimization setting technology in soaking section and optimization setting technology of cooling fan state in cooling section were formed. Finally, the comprehensive treatment technology was applied to a domestic iron and steel company and good results were achieved. The results show that the maximum warpage of the typical specification strip decreases from 17.0 mm to 5.9 mm, the warping of strip are compared before and after the process parameters optimizating. The production statistics of coating thickness of this type strip show that the average coating thickness on the upper and lower surfaces of the strip is reduced to the range required by the user after the C-shaped warping of the strip is improved.
钱胜, 顾清, 李学通, 白振华. 镀锌机组带钢C翘缺陷综合治理技术的开发[J]. 钢铁, 2021, 56(11): 160-168.
QIAN Sheng, GU Qing, LI Xue-tong, BAI Zhen-hua. Development of comprehensive treatment technology for strip C-shaped warp defect in galvanizing unit[J]. Iron and Steel, 2021, 56(11): 160-168.
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2021, Vol. 56 
