多辊连续矫直过程板带变形行为研究

发布时间：2018-06-23 08:37

本文选题：矫直 + 强化材料　；参考：《北京科技大学》2015年博士论文

【摘要】：辊式矫直作为修正轧后带钢缺陷的一道重要工序,普遍被用于消除由于外力作用、温度变化及内力消长而发生的弯曲或扭转变形。辊式矫直对带钢控制的实质是对其弯曲程度与内应力的控制,而经典模型假设带钢无初始应力,并且矫直过程不会产生新的残余应力,这对矫直过程的精确分析具有一定的局限性。本文着重研究矫直过程中的应力演变方式,以分析计算残余应力与残余曲率为核心,建立了基于解析法与数值法的强化材料连续矫直过程模型,并对不同矫直策略进行了深入研究。论文得出了以下创新性成果： (1)利用弹塑性力学基本原理对连续弹塑性弯曲过程的应力演变方式与规律进行了解析。研究表明连续弹塑性弯曲过程截面应力的演变依赖于弯曲变形历史,从理论上证明了考虑应力传递效应影响的弹塑性弯曲分析方法更适合于连续矫直过程。在此基础上对比分析了强化材料与理想弹塑性材料弯曲特性的差异,发现了强化材料弹塑性弯曲过程的回弹比更大,有利于其矫后保持受弯时的形态。 (2)利用应力线性叠加原则,建立了连续矫直过程应力分布求解模型,在此基础上对不同矫直策略进行了分析。结果表明：大变形矫直策略与小变形矫直策略相比,随弯曲次数的增加残余曲率在较小的范围内波动。从而证明了大变形矫直策残余曲率控制能力优于小变形矫直策略。 (3)选取残余曲率控制能力较优的大变形矫直策略,提出了残余曲率二次收敛矫直方案,并基于改进的复合梯形积分,建立了压弯挠度计算方法,实现了对矫直过程中截面力学参数与几何缺陷同步控制的矫直工艺设定方法。 (4)利用ANSYS/LS-DYNA仿真软件,建立了连续矫直过程有限元模型。对比数值解与解析解结果,得到截面边部纵向加载应力和卸载应力偏差分别为4.1%、9.31%；同时,采集现场实验矫直力数据,计算得到弯矩比变化过程曲线,与解析模型计算值偏差在13%以内。从而在数值模拟和现场实验两方面验证了连续矫直过程应力分布求解模型的正确性。
[Abstract]:Roller straightening is an important procedure to correct the defects of strip after rolling. It is widely used to eliminate the bending or torsional deformation caused by external force, temperature change and internal force change. The essence of roller straightening control of strip is to control the degree of bending and internal stress, while the classical model assumes that the strip has no initial stress, and no new residual stress will be produced in the straightening process. This is limited to the accurate analysis of straightening process. In this paper, the stress evolution mode in straightening process is studied. Based on the analysis and calculation of residual stress and residual curvature, a continuous straightening process model for strengthening materials is established based on analytical and numerical methods. Different straightening strategies are also studied. The main contributions are as follows: (1) the stress evolution mode and law of continuous elastic-plastic bending process are analyzed by using the basic principles of elastoplastic mechanics. It is shown that the evolution of cross-section stress in continuous elastic-plastic bending process depends on the history of bending deformation. It is theoretically proved that the elastic-plastic bending analysis method considering the effect of stress transfer effect is more suitable for continuous straightening process. On this basis, the difference between the flexural properties of the strengthened material and the ideal elastoplastic material is compared and analyzed. It is found that the springback ratio of the elastoplastic bending process of the strengthened material is greater than that of the ideal elastoplastic material. (2) based on the principle of linear superposition of stress, the stress distribution model of continuous straightening process is established, and the different straightening strategies are analyzed. The results show that the residual curvature fluctuates in a small range with the increase of bending times compared with the small deformation straightening strategy. It is proved that the residual curvature control ability of the large deformation straightening strategy is superior to that of the small deformation straightening strategy. (3) selecting the large deformation straightening strategy with the better residual curvature control ability, the secondary convergence correction scheme of the residual curvature is proposed. Based on the improved composite trapezoid integral, the calculation method of bending deflection is established, and the method of setting up the straightening process is realized. (4) the simulation software ANSYS / LS-DYNA is used to realize the simultaneous control of the cross-section mechanical parameters and geometric defects in the straightening process. The finite element model of continuous straightening process is established. By comparing the numerical solution with the analytical solution, the longitudinal loading stress and unloading stress deviation of the side of the section are found to be 4. 1 and 9. 31, respectively. At the same time, the field experimental straightening force data are collected and the bending moment ratio changing process curve is calculated. The deviation from the calculated value of the analytical model is less than 13%. The model of stress distribution in continuous straightening process is verified by numerical simulation and field experiment.
【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TG333.23

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