地铁铝合金牵引梁MIG焊接工艺分析及变形控制

发布时间：2018-04-24 12:20

  本文选题：铝合金 + 牵引梁　； 参考：《哈尔滨工业大学》2015年硕士论文

【摘要】：地铁的车体广泛采用密度低、耐腐蚀的高强度铝合金。由于铝合金散热快、热膨胀系数大,极易产生较大的残余变形,必须通过调校进行矫正,从而制约了铝合金构件的焊接生产效率。本文针对地铁铝合金牵引梁构件,借助数值模拟技术并与实验相结合,对传统焊接工艺进行优化,达到控制焊接变形、提高生产效率的目的。首先,根据牵引梁构件的结构特点及质量要求,分析牵引梁传统MIG焊接方法的特点及不足,指出X型坡口焊缝采用非对称的焊接顺序等工艺条件是牵引梁焊接角变形产生的主要原因。其次,对典型平板试件进行数值模拟,并通过平板试件的熔池形貌及热循环曲线,对数值模拟的热源模型进行校核,确保采用的热源模型的合理性。在此基础上,对牵引梁的传统焊接工艺进行数值模拟研究,获得牵引梁构件的焊接变形,并与测量的实验结果进行对比分析。按照传统的焊接方法,牵引梁构件的角变形在1.5°左右。最后,根据车间的实际情况,提出翻转交叉焊、双面双弧焊和反变形法等三种优化方案,并分别对三种方案进行数值模拟仿真研究。通过对三种方案的对比分析,指出双面双弧与反变形为较好的工艺方案,且两者组合为最佳的工艺方案,并对最佳工艺方案进行焊接试验验证。结果表明,按此优化方案,角变形能够控制在合理范围内,宏观上可以忽略不计,不影响牵引梁的平面度。研究成果已应用于指导牵引梁构件的实际焊接生产,并配套设计制作了工装夹具,合格率达到98%以上,提高了生产效率,降低了生产成本。地铁铝合金牵引梁焊接角变形的成功控制,对其他产品的工艺优化积累了宝贵的经验。
[Abstract]:High strength aluminum alloy with low density and corrosion resistance is widely used in the body of subway. Due to the rapid heat dissipation and large coefficient of thermal expansion of aluminum alloy, it is easy to produce large residual deformation, which must be corrected by adjustment, thus restricting the welding production efficiency of aluminum alloy components. In this paper, the traditional welding process is optimized with the aid of numerical simulation technology and experiment for the aluminum alloy traction beam of subway. The purpose of controlling welding deformation and improving production efficiency is achieved. First of all, according to the structural characteristics and quality requirements of the traction beam members, the characteristics and shortcomings of the traditional MIG welding method of the traction beam are analyzed. It is pointed out that the welding angle deformation of the traction beam is mainly caused by the unsymmetrical welding sequence of the X-groove weld. Secondly, the numerical simulation of typical plate specimen is carried out, and the heat source model of numerical simulation is checked through the molten pool morphology and thermal cycle curve of the plate specimen to ensure the rationality of the heat source model adopted. On this basis, the traditional welding process of the traction beam is studied by numerical simulation, and the welding deformation of the traction beam member is obtained, and the results are compared with the measured results. According to the traditional welding method, the angular deformation of the traction beam member is about 1.5 掳. Finally, according to the actual situation of the workshop, three optimization schemes are put forward, such as reverse cross welding, double-sided double-arc welding and reverse deformation method, and the numerical simulation and simulation of the three schemes are carried out respectively. Through the comparison and analysis of the three schemes, it is pointed out that the two sides double arc and reverse deformation are the better process plan, and the combination of the two is the best process plan, and the best process scheme is verified by welding test. The results show that the angle deformation can be controlled within a reasonable range according to the optimization scheme and the planeness of the tractive beam can be neglected in the macroscopic view without affecting the planeness of the traction beam. The research results have been applied to guide the actual welding production of the traction beam members, and the fixture has been designed and manufactured. The qualified rate is over 98%, which improves the production efficiency and reduces the production cost. The successful control of welding angle deformation of metro aluminum traction beam has accumulated valuable experience in optimizing other products.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U270.64;TG457.14

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