带钢起筋屈曲变形行为及控制策略研究

发布时间：2018-04-29 19:15

本文选题：带钢 + 起筋　；参考：《北京科技大学》2016年博士论文

【摘要】：随着带钢生产工艺、装备及控制技术的不断发展,带钢板形质量得到明显提高,达到了较高的水平。然而,生产中经常出现的起筋现象制约着带钢质量的进一步提升。由于导致带钢起筋的影响因素众多,因此,从理论上对起筋问题进行定量分析十分困难。目前,国内外对于带钢起筋问题的研究主要集中在起筋量的测量和预测方面,而对带钢起筋机理和控制方法的研究较少,对于起筋钢卷开卷后出现的局部浪形也无法给出合理的解释。因此,对起筋机理和控制策略的研究在学术和生产实践中具有重大的意义。本论文基于数值和解析方法,对轧制及卷取过程中带钢的起筋机理和控制策略进行深入研究,取得了以下创新性成果：(1)为了分析带钢的起筋机理,借鉴三维弹塑性变形的处理思想,建立了钢卷弹塑性应力场和起筋量计算模型。针对局部高点和局部浪形的不同特性,从应力角度分别分析了两种缺陷在卷取过程导致带钢起筋的根本原因,并分析了各影响因素对起筋量的影响,得到了局部高点引起的带钢起筋首先产生在钢卷最外层、局部浪形导致的带钢起筋首先产生在钢卷最内层的重要结论。(2)为了研究带钢起筋的临界应力及其与各影响因素间的关系,根据导致带钢起筋的局部高点和局部浪形的不同特点,基于应力函数假设和S.Timoshenko最小功原理,分别获得了首先产生起筋的钢卷最外层和最内层带钢的应力场分布,并基于伽辽金虚位移原理首次建立了起筋临界应力求解模型,分析了起筋临界应力与其影响因素间的关系,为带钢起筋控制提供了理论依据。基于米塞斯双向应力屈服准则建立了起筋量弹性极限的判定方法,并将二次摄动法引入到钢卷起筋后屈曲变形分析中,获得了后屈曲变形过程钢卷应力场与起筋挠度间的关系,完善了带钢起筋屈曲变形理论。(3)分析了各影响因素对冷轧过程带钢局部变形的影响,并建立了冷轧带钢屈曲失稳计算模型,为轧制中最大程度降低局部缺陷而不产生局部浪形提供了依据。综合起筋量模型、起筋临界应力模型、轧辊-轧件快速耦合变形模型和屈曲失稳求解模型,建立了冷轧原料局部高点极限值求解方法和基于PSODE算法的带钢起筋控制策略,形成了冷轧原料和冷轧过程两个层面的完整的起筋控制策略,为解决带钢起筋问题提供了技术支持。系统投入使用前后连续热镀锌生产线彩涂基料起筋回退率由原15.8%降低到0.18%,对提高带钢板形质量和工业生产具有重要的应用价值。
[Abstract]:With the continuous development of strip production technology, equipment and control technology, the strip shape quality has been obviously improved and reached a higher level. However, the reinforcement phenomenon often appears in production restricts the further improvement of strip quality. Because there are many factors that influence the steel strip reinforcement, it is very difficult to quantitatively analyze the reinforcement problem theoretically. At present, the domestic and foreign research on strip reinforcement is mainly focused on the measurement and prediction of the amount of reinforcement, but the research on the mechanism and control method of strip reinforcement is less. It is impossible to give a reasonable explanation for the local wave shape of steel coils after unwinding. Therefore, the research on reinforcement mechanism and control strategy is of great significance in academic and production practice. In this paper, based on numerical and analytical methods, the reinforcement mechanism and control strategy of strip during rolling and coiling are deeply studied. The following innovative results are obtained: 1) in order to analyze the mechanism of strip reinforcement, Based on the theory of three dimensional elastoplastic deformation, a calculation model of elastic-plastic stress field and stiffening capacity of steel coil is established. According to the different characteristics of local high point and local wave shape, the fundamental causes of two kinds of defects leading to strip reinforcement in coiling process are analyzed from the stress angle, and the influence factors on the amount of reinforcement are analyzed. It is obtained that the strip hoist caused by the local high point is first produced in the outermost layer of the coil. In order to study the critical stress and the relationship between the critical stress and the influence factors, according to the different characteristics of the local high point and the local wave shape, Based on the assumption of stress function and the principle of S.Timoshenko minimum work, the distribution of stress field in the outermost and innermost steel strips with the first reinforcement is obtained, and the solution model of critical stress is established for the first time on the basis of Galerkin's virtual displacement principle. The relationship between the critical stress and its influencing factors is analyzed, which provides a theoretical basis for strip reinforcement control. Based on the Mises bidirectional stress yield criterion, the method of determining the elastic limit of the reinforcement is established, and the quadratic perturbation method is introduced to the analysis of the post-buckling deformation of the steel coil. The relationship between the stress field of the steel coil and the deflection of the stiffener during the post-buckling deformation is obtained. The buckling deformation theory of steel strip is improved. The influence factors on the local deformation of strip during cold rolling are analyzed, and the calculation model of buckling instability of cold rolled strip is established. It provides a basis for minimizing local defects without producing local waves in rolling. Based on the reinforcement model, the critical stress model, the fast coupling deformation model and the buckling instability solution model, the local limit value of cold rolling material and the control strategy of strip reinforcement based on PSODE algorithm are established. A complete reinforcement control strategy for cold rolling raw material and cold rolling process is formed, which provides technical support for solving the problem of strip reinforcement. Before and after the system is put into use, the backing back rate of color coating base material in continuous hot dip galvanizing production line is reduced from 15.8% to 0.18%, which has important application value for improving strip shape quality and industrial production.
【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TG335.5

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