冷拔Q345钢无缝管成形数值仿真及工装优化研究

发布时间：2018-05-12 23:26

本文选题：数值模拟 + 管材冷拔　；参考：《南京航空航天大学》2017年硕士论文

【摘要】：在管材冷拔生产中,固定短芯棒拉拔工艺是最主要的方式之一。其中模具结构设计的合理与否直接关系到拉拔后管材的质量。本文中冷拔模具结构与传统模具不同,模具变形区是由一段直线和圆弧线组成的,造成管材的变形行为发生变化,所以借助有限元仿真技术来模拟钢管的冷拔过程。本文中成品管规格要求为88.9×76.2mm(外径×内径),材料为Q345钢,选用95×79mm的改制管冷拔一道次成形。在不同应变速率下进行Q345钢拉伸实验,选用两种方法进行J-C材料本构模型参数拟合,结果表明,优化计算法(L-M法)拟合后与实验数据吻合较好,曲线有很好的外推能力。通过模拟拉伸实验,确定韧性断裂准则损伤临界值DC。在管材稳定变形阶段,内模与外模过渡圆角连线区域内,钢管的等效应力达到最大865MPa;等效应变沿壁厚方向分布不均匀,在中间层应变最大;拔制后钢管轴向残余应力分布呈内拉外压状态;壁厚中损伤值最大为0.19,小于临界值;在实际生产中冷拔模具的入口圆弧处和过渡圆角处磨损最严重。同样在模拟后,模具工作表面磨损深度分布图中也出现两个极值点,最后从界面压力和相对流动速度解释了这种现象。选定模具结构参数范围,深入分析了模具半锥角、定径带长度、过渡圆角半径、过渡带长度和模具入口圆弧半径参数变化对拉拔力、模具最大磨损深度、损伤值分布、轴向残余应力分布的影响。最后借助正交实验法,在综合各指标基础上,确定了新型模具结构参数。使用新型模具拉拔后,拉拔力降低10%,最大磨损深度降低3%,轴向残余应力降低14%,损伤值由0.19降到0.15,且沿着壁厚分布均匀。
[Abstract]:In the production of tube cold drawing, fixed short mandrel drawing process is one of the most important ways. Whether the design of die structure is reasonable or not is directly related to the quality of tubing after drawing. In this paper, the structure of cold drawing die is different from that of traditional die. The deformation zone of die is composed of a straight line and arc line, which causes the deformation behavior of pipe to change, so the cold drawing process of steel pipe is simulated by finite element simulation technology. In this paper, the specification of finished pipe is 88.9 脳 76.2 mm (outer diameter 脳 inner diameter, material is Q345 steel). 95 脳 79mm modified tube is cold-drawn one time. In the tensile test of Q345 steel at different strain rates, two methods are used to fit the constitutive model parameters of J-C material. The results show that the optimum calculation method (L-M method) is in good agreement with the experimental data, and the curve has good extrapolation ability. The critical damage value of ductile fracture criterion is determined by simulated tensile test. In the stable deformation stage of the pipe, the equivalent stress of the steel pipe reaches the maximum of 865 MPA in the connecting region of the transition corner between the internal model and the external mold, and the equivalent strain distributes inhomogeneously along the direction of the wall thickness, and the maximum strain is found in the middle layer. After drawing, the axial residual stress distribution of the steel tube is in the state of internal tension and external compression, the maximum damage value of the wall thickness is 0.19, which is less than the critical value, and the wear of the inlet arc and the transition corner of the cold drawing die is the most serious in the actual production. There are also two extreme points in the distribution of wear depth on the working surface of the die after simulation. Finally, this phenomenon is explained from the interface pressure and the relative flow velocity. The parameters range of die structure is selected, and the variation of die semi-conical angle, diametric belt length, transition radius, transition zone length and die inlet arc radius parameters on drawing force, maximum wear depth of die and distribution of damage value are analyzed in depth. Influence of axial residual stress distribution. Finally, the new die structure parameters are determined by the orthogonal test method and based on the synthesis of each index. After drawing, the drawing force is reduced by 10%, the maximum wear depth is reduced by 3 parts, the axial residual stress is reduced by 14%, the damage value is reduced from 0.19 to 0.15, and the distribution along the wall thickness is uniform.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG356.52

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