摘要：随着制造业的不断发展，厚板焊接应用也逐渐变得普遍，特别是在船舶、压力容器和海上设备的建设中。由于焊接结构的复杂性，垂直焊接工艺在这些领域至关重要。对于厚板焊接，窄间隙焊接和常规焊接方法相比，具有成本低，生产效率高，热输入低，质量好，变形小等优点，其中摇动电弧窄间隙GMAW立焊不仅可以确保足够的侧壁渗透，而且可以抑制由于其弯曲的导电棒而导致的垂直焊接期间由于重力作用引起的熔融金属的下淌，其被认为是在窄间隙全位置焊接中的一个有希望的方法。为了能够使垂直位置焊接工艺更好的使用到制造业当中去，有必要对其进行一定的研究。特别是垂直位置的摇动电弧窄间隙焊接涉及更多的工艺参数，优化起来比较困难。为了使垂直焊缝得到控制，需要更好地了解摇动电弧窄间隙焊在垂直位置的熔池动态特性。

本文主要综合考虑摇动电弧窄间隙GMAW立焊的接头几何特征，热源的移动轨迹建立了适合摇动电弧窄间隙GMAW立焊的熔池动态分析的的三维数值分析模型，利用FLUENT 软件对不同摇动频率条件下的摇动电弧窄间隙GMAW立焊的温度场和流场进行计算，基于计算结果对其流体流动进行分析，并将得出的熔池尺寸的计算结果和实验结果进行比较，发现两者基本相同，说明了模型的准确性。研究结果表明，当摇动频率f=0Hz时，焊缝成形较差，熔融金属在重力作用下下淌严重，随着摇动频率增加，下淌现象逐渐改善，当f=0.8Hz时，下淌现象消失，并且焊缝成形良好，焊缝平整，横截面关于焊缝中心对称。

关键词：摇动电弧窄间隙；立焊；频率；熔池形态分析

Abstract：With the continuous development of manufacture, applications of welding in thick plate have gradually become common, especially in the ship, pressure vessels and marine equipment construction. Due to the complexity of the welding structure, the vertical welding process is of vital importance in these areas. For the thick plate welding, comparing with the conventional welding methods, narrow gap welding have following advantages of low cost, high production efficiency, low heat input, good quality, small deformation, where GMAW welding of swing arc narrow gap can not only ensure sufficient sidewall penetration, but also suppress the sagging of molten metal caused by gravity during vertical welding due to its curved conductive rod, which is considered to be a promising method of welding in full position. In order to be able to make a better use of vertical position welding to the manufacturing industry, it is necessary to carry out some research. Especially the vertical position of the swing arc narrow gap welding involving more parameters, it is more difficult to optimize. In order to control the weld in vertical position, it is necessary to understand the dynamic characteristics of the baths in the vertical position.

In this paper, the geometrical features of the joint of the GMAW of swing arc narrow nap in vertical position have been discussed, and the trajectory of the heat source has been established. Based on these，the three-dimensional numerical analysis model of the molten pool for the dynamic analysis is established. The Fluent software is used to analyze the temperature field and flow field at different swing frequency. The analysis of the fluid flow is based on the calculation results, and the results of the calculated pool size are compared with the experimental results, and it is found that the two are basically the same , which illustrates the accuracy of the model. The results show that when the swing frequency f = 0Hz, the weld is poor in molding, and the molten metal is sagged due to gravity. With the increase of the swing frequency, the phenomenon of sagging improves. When f = 0.8Hz, the phenomenon of dropping disappears, and the weld is well shaped and is flat. At the same time, the cross section is symmetrical about the weld center.