基于Fluent的窄间隙TIG焊枪结构优化设计

Optimization design of narrow gap TIG welding torch’s structure based on Fluent

针对大型工程项目当中的大口径、大厚壁、深窄间隙坡口的管道对接需求,设计了一款窄间隙TIG(NG-TIG)焊枪,并实现高效率焊接。该枪体为非对称的一体化扁平式结构,在间隙宽度为10 mm、深度15 mm的U形坡口内进行焊接试验,发现在窄间隙焊接过程中出现了焊缝成形不连续、焊缝出现气孔及电弧不稳等问题。为了达到理想的焊接工艺效果,文中通过Fluent软件进行了数值模拟仿真分析,对窄间隙TIG焊枪的保护气输送通道及其出口布局进行了结构优化,并且在与传统TIG焊枪的保护气体流量及运动轨迹等方面进行对比后,发现保护气体在钨极周围均匀向外扩散,且速度与传统TIG焊枪的气体保护状态接近,从而确定了窄间隙TIG焊枪的气体保护结构。结果表明,焊枪在焊接电流为120 A,焊接速度为100 mm/min,气体流量在25 L/min的焊接工艺参数下电弧稳定、无飞溅,焊缝成形美观无缺陷。

In view of pipe butt requirements of large diameter, thick wall and deep narrow gap groove in large engineering projects, a narrow gap TIG(NG-TIG) welding gun was designed to achieve high efficiency welding. The gun body was an asymmetrical integrated flat structure. The welding experiment was carried out in U groove with gap width of 10 mm and depth of 15 mm. It was found that there appeared some problems such as discontinuous weld forming, porosity and arc instability in narrow gap welding process. In order to achieve ideal effect of welding process, numerical simulation analysis was carried out by Fluent software in this paper to optimize structure of protective gas transport channel and outlet layout of narrow gap TIG welding gun. After being compared with traditional TIG welding gun in terms of protective gas speed and movement track, it was found that protective gas evenly diffused outward around tungsten electrode and its velocity was close to the gas protection state of traditional TIG welding gun, so as to determine gas protection structure of narrow gap TIG welding gun. The welding experiment showed that welding gun had characteristics of stable arc and no splash in the welding process under welding parameters of 120 A welding current, 100 mm/min welding speed and 25 L/min gas flow, and weld was well formed without defects.