共查询到19条相似文献,搜索用时 125 毫秒
1.
针对带钢连退过程中的热瓢曲问题,充分考虑到连退机组的设备与工艺特点,从内力、外力两方面因素分析了热瓢曲以及横向压应力的产生机理,阐述了热瓢曲的发生规律,首次提出了瓢曲指数的新概念,给出了相应的瓢曲临界条件,建立了一套适合于连退过程的带钢热瓢曲指数的计算模型,定量分析了不同工艺段内带钢瓢曲指数分布规律以及相同工艺段内来料板形、横向温差、炉辊辊型、摩擦因数、设定张力、通板速度等因素对带钢热瓢曲指数的影响,并将相关理论应用到生产实践,开发出了“连退机组通板过程带钢瓢曲预报软件”,实现了对连退过程带钢瓢曲的在线预报,为瓢曲缺陷的预防和控制奠定了坚实的理论基础。 相似文献
2.
3.
4.
5.
主要分析了在连续退火炉内热处理薄带钢时,炉辊的凸度、炉辊中间平台区长度以及辊面粗糙度等因素对带钢产生瓢曲的影响规律。旋转的炉辊对带钢宽度方向上产生一个压缩作用,这种压缩作用会引起带钢的弯曲和折皱,折皱经过炉辊后就会有可能引发热瓢曲。推导出一个计算瓢曲临界张力的公式,公式表明,临界瓢曲应力和[(带钢厚度×屈服强度)/(炉辊凸度×摩擦因数)]2成正比。 相似文献
6.
简要介绍了冷轧连退机组使用的炉辊的形状、不同位置的炉辊在机组运行时凸度的改变情况,以及炉辊凸度改变对机组带钢产生瓢曲和跑偏擦边的影响.通过对连续退火炉内炉辊在热态下凸度变化情况的研究,在带钢规格变化过程中针对性地采用优化降速、降温等过渡策略,较大幅度地减少了瓢曲、断带的发生;同时,通过数据计算的方法,引入一个直观的瓢曲风险系数的方法,使操作更加直观.对所述方法的综合使用,基本消除了带钢瓢曲现象的发生,使生产稳定性得到了很大的提高. 相似文献
7.
8.
9.
10.
11.
During and after rolling or flattening of metal strips and plates the permissible deviations from flatness are described by the permissible absolute wave height and the flatness index. Both values can be determined on a measuring table while the material is not subjected to global tension. Because this procedure is expensive, time‐consuming and allows measurement only at discrete positions along the strip length, on‐line flatness measuring systems are used which can detect the distribution of longitudinal tensile stresses distributed across the strip width allowing for the calculation of the flatness index. This value does not always agree with the value obtained directly by measuring on the table even when the measurement of the longitudinal tensile stress distribution operates perfectly. It can be shown that the measurement of the tensile stress distribution does not give a direct indication on the wave height in the tension‐free state determined on the measuring table. To explain the relationship between tensile stress distribution in the strip and the flatness measurement on the measuring table, the buckling behavior is analysed both with and without dead load for simple symmetrical residual stress distributions resulting, e.g., from the rolling process. Based on the knowledge of the distribution of the longitudinal residual stresses across the strip width, the flatness index and the wave height can be determined by using a specialized finite element model. If the direct measurement is performed under action of dead load, large differences between the directly and indirectly obtained flatness index are observed. Below a certain limit of the intensity of the residual stress distribution the strips and plates lie flat on the measuring table. Above this limit the strip lying on the table exhibits post‐bucking deformations. In the latter case, the wave height increases with strip thickness and intensity of residual stresses. 相似文献
12.
The previous tension setting for the continuous annealing process (CAP) is not comprehensive; that is, it does not synthetically consider the factors of strip deviation, buckling, flatness and width narrowing. To address this issue, this study integrated the mechanical and technological characteristics of a continuous annealing line to present a comprehensive control index that can characterise the stability of a travelling strip. Meanwhile, strip deviation, buckling, strip shape and width narrowing were regarded as constraints in each process section. A comprehensive optimisation technique for the tension setting during CAP was then established, and a related theory was applied during production. In addition, a comprehensive tension setting optimisation software was developed for a cold rolled strip during continuous annealing, and the comprehensive optimisation of the tension parameters in each process section was realised. A practical implementation proves that the developed technique exhibits good application effects and considerable application values. 相似文献
13.
对H型钢轧制过程中腹板波浪的产生机理及形成条件进行了研究。利用解析的方法,给出了腹板产生屈曲的临界应力和应变。使用有限元软件MSC.Marc, 建立了H型钢轧制的弹塑性有限元模型,并成功地仿真出了腹板屈曲现象,给出了此过程中轧件的应力和变形规律。得到了出现腹板波浪时腹板和翼缘相对压下量的临界比值和半波长等特征值参数。 相似文献
14.
The tilted waves in steel strip during rolling and leveling of sheet metal can be classified into two different types of buckling, oblique and herringbone buckling, respectively. Numerical considerations of oblique and herringbone buckling phenomena are dealt with by the spline finite element method (FEM). It is pointed out that the shear stress due to residual strains caused by the rolling process or applied non-uniform loading is the main reason of oblique and herringbone buckle. According to the analysis of stress distribution in plane, the appropriate initial strain patterns are adopted and the corresponding buckling modes are calculated by the spline FEM. The developed numerical model provides an estimation of buckling critical load and wave configuration. 相似文献
15.
LI Jun) ZHANG Lixiang) ) Research Institute Baoshan Iron & Steel Co. Ltd. Shanghai China ) Shanghai Jiao Tong University Shanghai China 《Baosteel Technical Research》2010,(Z1)
In continuous annealing lines/hot galvanizing,strips are guided by upper and lower rolls in an alternate up and down vertical motion.This kind of process consisting of heating,soaking,and cooling furnaces(or zones) has several advantages in terms of productivity and product quality.Main problems encountered in continuous annealing lines are misguiding and formation of buckling.The strip buckling causes the strip to be rejected and,in the worst case,the strip breaks and the continuous annealing lines are ... 相似文献
16.
17.
为了揭示冷轧带材前屈曲面内残余应力与后屈曲挠度、后屈曲残余应力的关系,引入非协调F?ppl-von Kármán方程组,建立了两边自由无限长带条后屈曲的非线性偏微分方程组边值问题模型。根据冷轧带材后屈曲挠度具有轧制方向单波长周期性变化的特点,将非线性偏微分方程组边值问题分离变量而形成非线性常微分方程组边值问题。将边值问题中涉及的各物理量无量纲化,并分析这些物理量的数量级,进而确定出带有待定系数的无量纲挠度函数的形式。然后将总势能写成只与无量纲挠度函数有关的形式,并利用Ritz法确定各待定系数。最后采用其他文献中的计算结果与本文提出方法的计算结果进行对比,发现较为吻合,并解释了产生误差的原因。同时针对某冷轧厂产品计算出后屈曲释放后的残余应力,并计算了使带钢保持平直的最小张应力,为板形仪的合理应用提供了参考。 相似文献
18.