牵引梁激光复合焊焊接变形数值模拟

发布时间：2018-01-10 15:16

本文关键词：牵引梁激光复合焊焊接变形数值模拟　出处：《西南交通大学》2017年硕士论文　论文类型：学位论文

【摘要】：地铁作为一种随着城市发展而兴起的公共轨道交通方式,正在受到越来越多城市的欢迎。牵引梁是地铁车辆底架的重要部分,主要通过大量的焊接加工而成。然而,焊接变形始终伴随着焊接过程出现,会对产品的装配、寿命和安全性带来影响,因此需要对焊接变形进行控制。本文以地铁车辆底架的牵引梁作为研究对象,使用SYSWELD软件对牵引梁在不同焊接顺序和焊接约束下的焊接变形进行数值模拟,以选出变形更小的焊接工艺方案。本文的主要内容:首先,叙述了本文的选题背景和意义,从设计措施和工艺措施两个方面简述了变形控制的方法,再综述了焊接模拟和激光-MIG复合焊数值模拟的国内国外的研究现状。其次,对焊接数值模拟的常用理论、热源类型和软件进行简单的介绍。再次,对牵引梁的焊缝进行分类。根据实际的焊接工艺,基于热弹塑性法对不同焊接接头进行热源校核,使之与实验得到的焊缝截面基本一致,再提取各接头的固有应变。然后,将提取得到的固有应变值通过等效温度法施加到牵引梁中进行计算,并将计算得到的变形与实际测量变形进行比较。最后,本文选择了3种不同的焊接约束和3种不同的焊接顺序工艺对牵引梁焊接变形进行优化。研究结果表明:使用3D高斯+双椭球热源模型模拟激光-MIG复合焊,模拟焊缝截面与实验所得截面非常接近,验证了热源模型选择的正确性;同样的焊接工艺条件下,模拟变形结果与实际测量的变形结果非常接近,两者相对误差为8.23%,证明了使用固有应变法预估焊接变形的可行性;不同的焊接约束和顺序对焊接变形存在影响,牵引梁焊后发生了不同程序的角变形、收缩变形和挠曲变形;牵引梁在按照文中所述改变焊接约束时角变形最多减小了 76.95%,在改变焊接顺序时收缩变形最多减小了8.00%。
[Abstract]:As a kind of public rail transit mode rising with the development of the city, subway is being welcomed by more and more cities. The traction beam is an important part of the subway vehicle underframe. However, welding deformation is always accompanied by welding process, which will have an impact on product assembly, life and safety. Therefore, it is necessary to control the welding deformation. This paper takes the traction beam of subway vehicle underframe as the research object. The SYSWELD software is used to simulate the welding deformation of the traction beam under different welding sequences and constraints in order to select the welding process with smaller deformation. The main contents of this paper are as follows: firstly. The background and significance of this paper are described, and the methods of deformation control are briefly described from two aspects: design measures and technological measures. Then the domestic and foreign research status of welding simulation and laser-MIG hybrid welding numerical simulation is summarized. Secondly, the common theory of welding numerical simulation, heat source type and software are briefly introduced. Thirdly. According to the actual welding technology, the heat source of different welded joints is checked based on thermoelastic-plastic method, which is basically consistent with the weld section obtained by experiments. Then the natural strain of each joint is extracted. Then, the extracted natural strain value is applied to the traction beam by equivalent temperature method, and the calculated deformation is compared with the actual measured deformation. In this paper, three different welding constraints and three different welding sequence processes are selected to optimize the welding deformation of the traction beam. The results show that 3D Gao Si is used to optimize the welding deformation of the traction beam. The double-ellipsoid heat source model is used to simulate the laser-MIG hybrid welding. The simulated weld section is very close to the experimental cross section, which verifies the correctness of the heat source model selection. Under the same welding process conditions, the simulated deformation results are very close to the actual measured deformation results, and the relative error between them is 8.23, which proves the feasibility of using inherent strain method to predict welding deformation. Different welding constraints and order have influence on welding deformation. After welding, different programs of angular deformation, shrinkage deformation and flexural deformation occur in the traction beam. The angular deformation of the traction beam decreases by 76.95 when the welding constraint is changed according to the paper, and the shrinkage deformation decreases by 8.00 when the welding sequence is changed.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U270.6;TG404

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