半浮芯棒连轧管成型的有限元分析及轧辊孔型改进

【作者】 杜磊；

【导师】 唐华平；

【作者基本信息】 中南大学 ， 机械设计及理论， 2010， 硕士

【摘要】 无缝钢管在工业生产中被广泛应用于管道输送、热工设备、机械制造、石油地质钻探、化学高压容器等。在无缝钢管的热轧工艺中,钢管的产品质量与轧机设备密切相关,其中半浮芯棒连轧管工艺是钢管成形的重要工序。因此合理确定其轧制参数是设计和生产中都有待解决的关键问题,也是当前的研究热点。为此,围绕着“连轧管机孔型改进”,本文展开了如下几方面工作。首先,阐述了钢管连轧理论,以半浮芯棒连轧管的工艺流程和轧制过程为基础,对连轧管机孔型的设计方法进行介绍。其次,为了更真实的对钢管材料进行模拟,设计了高温力学试验,研究了钢管用20#钢在不同温度和形变速率下的σ-ε曲线。在此基础上,采用MATLAB软件建立了20#钢在高温下的粘弹-塑性模型本构关系。分析表明,该本构方程在试验的温度和形变速率条件下具有较好的效果。然后,在ANSYS/LS-DYNA软件环境下建立了6机架半浮芯棒连轧管成型过程的三维热固耦合有限元模型,并针对Φ109mm×6mm规格进行了模拟分析。通过对比模拟结果与荒管实物知,两者孔型形状在一个圆周内的变化规律相似。验证了该模型的可靠性和该分析方法的可行性。最后,分析指出了荒管形状不规则的主要原因是：孔型和轧件形状不相吻合而导致接触的非同时性,使接触边界具有空间曲线(非平面性)的特点间接导致了荒管外径分布不均；孔顶区和侧壁区摩擦力分布的方向相反间接导致了荒管壁厚分布不均。通过改进调整偏心距和轧辊辊缝,荒管形状得到了明显改善。数据表明,外径与目标值109mm的平均相对误差由1.680%降到了0.861%；壁厚与目标值6mm的平均相对误差由3.569%降到了2.722%.更多还原

【Abstract】 Seamless pipes are widely applied to ducting, thermal engineering equipment, machinery manufacturing, petrolic and geological rig, chemical high pressure container, and so on. Quality of pipes is intimately relative to rolling mill, and the technology of semi-floating mandrel pipe mill is an important procedure of pipe deformation in hot rolling process. Determining rolling parameters reasonably is a key problem to be resolved both in design and production, and it is also hot spot of research at present. Surrounding improvement of hole shape of mandrel pipe mill, some works were performed.Firstly, some theories of pipe milling were illustrated, based on the technology process and rolling mill procedure of semi-floating mandrel pipe mill, hole shape of rolling mill were designed.Secondly, in order to simulate pipe material more truly, mechanical experiment at high temperature was designed and introduced. Curvesσ-εof steel 20# were studied in different temperatures and strain rates. Based on it, constitutive relation of elastic viscoplastic thermal material was founded at high temperature by software MATLAB. The constitutive function was effective and noticeable at conditions of temperatures and strain rates in experiment.Thirdly, Finite element dynamic model was established on deformation of 6-stand semi-floating mandrel pipe mill by ANSYS/LS-DYNA at 3D thermosetting coupling, and the standardΦ109mm×6mm was simulated. Based on the comparison between simulated results and shell object, conclusions were reached that variational regularities of their hole shapes were similar in circumferential direction. It was validated that reliability of the model and feasibility of the method.Finally, formative causation of irregular shape of shell section were analysed:shapes incongruity between rolling mill and pipe caused contact did not occur at one time, character that contact boundary was a spatial curve caused asymmetrical distribution of shell exterior diameters indirectly; it indirectly cased asymmetrical distribution of shell thickness that inverse directions of friction at hole top area and lateral wall area. Shell shape was improved obviously after adjusting eccentricity and rolling mill gap. Data displayed:average relative tolerance beteeen exterior diameter and its target 109mm was decreased from 1.680% to 0.861%; average relative tolerance beteeen thickness and its target 6mm was decreased from 3.569% to 2.722%.更多还原