摩擦对宽厚板热轧过程宽展影响的数值模拟

发布时间：2018-08-18 18:05

【摘要】：宽厚板是国家钢铁产业的重要组成部分,广泛应用于军事、工业、农业等国民经济建设的各个领域。在宽厚板热轧生产中,轧件尺寸控制不良造成大量的切头尾、切边损失,从而影响了轧件成材率的提高。轧件厚度尺寸在制定轧制工艺时就已确定,轧制变形过程中宽度尺寸和长度尺寸相互影响,相互制约,合理控制轧制变形过程中宽度变化对轧件尺寸控制具有重要意义。由于宽厚板热轧过程的宽展属于自由宽展,摩擦对轧件的变形过程具有不可忽视的作用。研究轧制过程中摩擦对宽展变形的影响可为轧件宽度的控制提供依据。因此,本文以宽厚板热轧过程中宽展为研究对象,采用数值模拟的方法研究了轧制过程中摩擦对宽展变形的影响规律。首先,对宽展的影响因素及轧制过程中摩擦对变形的影响进行了综合分析,并总结了轧制过程中摩擦的研究进展和广泛使用的宽展计算公式。采用有限元软件MSC.Marc,建立了宽厚板热轧过程三维热-力耦合有限元模型。为验证有限元模型的可靠性,采用上述模型对实际宽厚板轧制过程进行模拟。模拟宽展和实测宽展符合较好,证明了模型的可靠性,这为开展摩擦对宽展影响规律研究奠定了工作基础。其次,利用上述有限元模型对四种常见尺寸的宽厚板轧件在不同摩擦系数和不同压下量条件下的轧制过程进行大量有限元模拟。结果表明,纵向摩擦力主要分布在宽度中心区域,横向摩擦力集中在轧件边部,摩擦力的大小均随摩擦系数的增加而增加。摩擦系数的变化对轧件表层金属宽向流动有一定影响,对下层金属宽向流动影响较弱。随摩擦系数的增加轧件侧边在自由表面处的宽展减小,厚度对称面处的宽展增加。轧件的平均宽展随摩擦系数的增加而降低,这种变化趋势随压下量的增加和轧件宽度的减小而愈显著。在以上宽展规律和模拟宽展数据的基础上,用摩擦系数修正了芝原宽展计算公式。修正后的芝原宽展公式计算的宽展与模拟的宽展符合较好,可为宽厚板轧制过程中精确地控制宽展提供一定参考。
[Abstract]:As an important part of national steel industry, wide and thick plate is widely used in military, industrial, agricultural and other fields of national economic construction. In the hot rolling production of wide and thick plate, the poor control of the size of the workpiece causes a lot of loss of the cutting end and the end, thus affecting the improvement of the yield of the rolled piece. The thickness dimension of rolling piece has been determined when the rolling process is made. The width dimension and length dimension influence each other and restrict each other in the process of rolling deformation. It is of great significance to control the width change during rolling deformation process reasonably. Because the spread of the hot rolling process is free, friction plays an important role in the deformation process of the workpiece. The study of the influence of friction on the width of rolling can provide the basis for the control of the width of rolling piece. Therefore, in this paper, the influence of friction on the spread deformation of the hot rolling process is studied by numerical simulation, taking the width spread in the hot rolling process as the research object. Firstly, the influence factors of width expansion and the influence of friction on deformation in rolling process are analyzed synthetically, and the research progress of friction in rolling process and the widely used formula for width expansion are summarized. Using the finite element software MSC.Marc, a three-dimensional thermal-mechanical coupled finite element model for the hot rolling process of wide and thick plates is established. In order to verify the reliability of the finite element model, the rolling process of practical wide and thick plate was simulated by the above model. The result shows that the model is reliable, which lays a foundation for the study of the influence of friction on the spread. Secondly, the finite element model is used to simulate the rolling process of four kinds of wide and thick plate under different friction coefficient and different reduction. The results show that the longitudinal friction is mainly distributed in the center of the width and the transverse friction is concentrated on the side of the workpiece, and the friction force increases with the increase of the friction coefficient. The variation of friction coefficient has a certain influence on the wide flow of the metal in the surface layer of the workpiece, but it has a weak effect on the wide flow of the metal in the lower layer. With the increase of friction coefficient, the width of the side edge of the workpiece decreases at the free surface, and the width at the thickness symmetric surface increases. The average width of workpiece decreases with the increase of friction coefficient, and the change trend is more obvious with the increase of reduction and the decrease of the width of rolling piece. On the basis of the above expansion law and the simulated expansion data, the formula for calculating the spread of sesame was modified by the friction coefficient. The result of the modified formula is in good agreement with that of the simulation, which can provide a reference for the accurate control of the spread in the rolling process of thick and wide plate.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG335.5

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