镀锌机组带钢C翘缺陷综合治理技术的开发

Development of comprehensive treatment technology for strip C-shaped warp defect in galvanizing unit

为了研究带钢热镀产品C翘板形缺陷导致其镀层不均匀性严重问题,优化热镀锌机组连退工艺过程,开发带钢C翘缺陷综合治理技术。首先考虑热镀锌连退过程的设备与其工艺特点,分析C翘板形发生机理,明火烧嘴状态、辐射管状态、风机状态、带钢重力、上游工艺段遗传板形等影响因素,使得带钢表面各处存温度差异性较大,致使带钢横向残留塑性变形在其厚度方向分布均匀,当其超过其临界失稳条件而发生C翘。然后,从系统学的观点出发建立兼顾C翘缺陷影响因素的连退炉系统函数,考虑到连退炉多变量耦合、复杂非线性特点,以工艺段为单位将连退过程划分子系统,以各工艺段板形翘曲最小为目标,基于带钢C翘预报模型分别建立加热段温度优化目标函数、均热段温度优化目标函数、冷却段冷却风机状态优化目标函数,并以各工艺段目标函数相叠加的形式建立系统函数。得出了连退过程各工艺段工艺参数综合优化方法,制定其工艺优化流程,并形成加热段温度优化设定技术、均热段温度优化设定技术、冷却段冷却风机状态优化设定技术等关键技术。最后,将该综合治理技术应用于国内型钢铁机组取得良好效果。结果表明,典型规格带钢在连退过程各工艺参数优化前后对比,其最大翘曲量由17.0 mm降至5.9 mm;该类型带钢的镀层厚度生产统计数据显示,带钢C翘板形改善后,带钢上下表面平均镀层厚度降至用户要求的范围内。

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.