连续热镀锌线气刀处带钢板形研究

发布时间：2018-12-12 06:17

【摘要】：镀锌层的厚度和均匀度很大程度上影响镀锌板使用性能,是镀锌板质量评估的重要指标。生产过程中,带钢经过锌锅中的三个辊子时会发生翘曲变形(主要是“C翘”),使得带钢在气刀处的镀锌层无法保持期望的厚度和均匀度,影响镀锌板的质量。针对该问题,本文分别以风箱带钢系统和辊子带钢系统为研究对象,利用有限元仿真技术,针对某一规格的带钢,对气刀处的板形进行了深入的研究,系统讨论了校正辊对带钢板形的校正过程和机理,为实际生产中控制板形、提高镀锌层质量提供一定的理论依据和技术指导。具体工作如下:(1)风冷段不均匀冷却对气刀处板形的影响大小评估。评估分两步来完成。1)采用带钢不动、风箱(冷源)向下移动的求解策略,对一段长12m的带钢的冷却过程进行热机耦合分析。结果表明,非均匀冷却后,横截面发生了些微“C翘”。同一横截面上中点位移与各自两端点位移差值可达到0.2×10-2mm。2)再忽略风箱对带钢的冷却作用,以整个出锌锅上行段带钢为对象,在风箱入口截面(距离带钢顶端19m)的中部施加一个矩形分布载荷,人为地使其产生3mm的“C翘”。有限元计算结果表明,气刀处的位移差几乎为零。故冷却段的非均匀冷却对气刀处的板形影响可以忽略不计。(2)以锌锅内的辊子带钢系统为研究对象,利用有限元软件MSC.Marc进行弹塑性接触建模并仿真计算。结果表明,1)确实板形平整的来料,经过沉没辊之后发生较大“C翘”。2)校正辊对经过沉没辊后翘曲的板形确有校正作用,而且对各横截面的校正作用基本一致。3)带钢经过沉没辊后之所以发生“C翘”,校正辊之所以对带钢板形有“校正作用”,盖源于“拉矫作用”破坏或改善了应力沿带钢宽度方向的分布规律:或使其不均匀程度增加,导致“C翘”程度增大,或使应力变小,并趋于均布,导致带钢平整。4)上推量不宜太大。对一定规格的带钢和钢种,上推量存在一个最优值。(3)针对不同钢种,利用所建立的弹塑性接触模型,评估校正辊上推量、带钢张力、带速和带钢与辊面间的摩擦系数等主要参数对气刀处带钢板形的影响。为了减少计算量,利用正交试验法来筛选参数组合,建立四因素三水平的正交试验表,求得各个因素的影响大小顺序以及表中所设参数的水平值的最佳参数组合。在此基础上再进行调试优化,得到使带钢在气刀处保持平整的最优参数组合。在各钢种的最优参数组合下,气刀处带钢边缘与宽度中点沿厚度方向的位移差不超过0.22?10-3mm,远小于工艺要求的锌层厚度。
[Abstract]:The thickness and evenness of galvanized coating greatly affect the performance of galvanized sheet, which is an important index to evaluate the quality of galvanized sheet. During the production process, the strip will warp when it passes through three rollers in the zinc pot (mainly "C warping"), which makes the galvanizing layer at the air knife place unable to maintain the desired thickness and uniformity, which affects the quality of the galvanized sheet. In order to solve this problem, this paper takes the bellows strip system and the roller strip system as the research objects, and makes use of the finite element simulation technology to study the flatness of a certain size strip. The correction process and mechanism of correction roll for strip shape are discussed systematically, which provides certain theoretical basis and technical guidance for controlling the shape of plate and improving the quality of galvanized layer in actual production. The main works are as follows: (1) the influence of uneven cooling in air cooling section on the shape of the blade is evaluated. The evaluation is carried out in two steps. 1) the cooling process of a 12m long strip is analyzed by thermo-mechanical coupling using the solution strategy of strip immobility and bellows (cold source) downward movement. The results show that a little "C warp" occurs in the cross section after non-uniform cooling. The difference between the midpoint displacement of the same cross section and that of the two ends can reach 0.2 脳 10-2mm.2) and then the cooling effect of the bellows on the strip is ignored, and the whole upstream section of the zinc pot is taken as the object. At the middle of the inlet section of the bellows (19 m from the top of the strip), a rectangular distributed load is applied to make the 3mm "C warp". The finite element calculation results show that the displacement difference is almost zero. Therefore, the effect of non-uniform cooling on the shape of the gas cutter can be neglected. (2) taking the roller strip system in the zinc pot as the research object, the elastic-plastic contact modeling and simulation are carried out by using the finite element software MSC.Marc. The results show that: 1) the shape of the submersible roll is flat and the "C warping" occurs after the sunken roll. 2) the correction roll has the function of correcting the shape of the submersible roll. Moreover, the correction effect on each cross section is basically the same. 3) the "C warp" occurs after the strip passes through the sunken roll, and the correction roll has the "correction effect" on the strip shape. The cover is derived from "tension and correction", which destroys or improves the distribution of stress along the width of the strip: or increases its inhomogeneity, resulting in an increase in the degree of "C warp", or makes the stress smaller and tends to homogenize, Lead to strip leveling. 4) push up should not be too large. There is an optimal value for the upward push of strip and steel grades of certain specifications. (3) for different types of steel, the elastoplastic contact model is used to evaluate the upward push of correction roll and the tension of steel strip. The influence of main parameters such as strip velocity and friction coefficient between strip steel and roll surface on strip shape at air cutter. In order to reduce the amount of calculation, the orthogonal test method is used to select the parameter combination, and the orthogonal test table with four factors and three levels is established, and the order of influence of each factor and the optimal combination of the horizontal values of the parameters in the table are obtained. On the basis of this, the optimum parameter combination of strip steel is obtained to keep the strip flat at the air cutter. Under the combination of the optimum parameters of each steel, the displacement difference between the edge and the middle point of the strip at the air knife along the thickness direction is not more than 0.22 脳 10 ~ (-3) mm, which is far less than the thickness of the zinc layer required by the process.
【学位授予单位】：安徽工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG173

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