药芯焊丝TIG焊电弧特性的光谱分析

The Spectral Analysis of TIG Welding Filled with Flux-Cored Wire

利用光谱诊断方法结合高速摄像研究所提出的药芯焊丝的填丝TIG焊接新工艺的电弧特性,借助高速摄像研究药芯焊丝TIG焊的熔滴过渡方式;通过对焊接电弧进行光谱采集点扫描,对采集的谱线进行元素标定,以药粉中活性元素K和Na作为追踪目标,统计得到电弧中药粉成分的分布范围;并利用Boltzmann图法计算TIG焊电弧的温度场分布,分析了熔滴过渡方式对电弧温度场分布的影响。研究结果表明,通过调整丝极间距,得到药芯焊丝TIG焊的三种典型的熔滴过渡方式:滴状过渡(2mm)、渣柱过渡(5mm)和搭桥过渡(7mm)。药粉中的活性元素K和Na等集中分布在熔池上方的电弧空间,且其分布受丝极间距的影响,丝极间距越小其分布越靠近钨极,容易造成对钨极的污染。不填丝TIG焊的电弧温度分布呈钟罩形,等温线关于钨极轴线近似对称分布;与不填丝TIG焊相比,药芯焊丝TIG焊的电弧温度场受熔滴过渡的影响发生了不同程度的扭曲,滴状过渡的电弧温度场扭曲严重,焊接过程中飞溅较大;相比于滴状过渡,渣柱过渡和搭桥过渡的电弧温度场扭曲程度较小且焊接过程稳定,适合该TIG焊方法的使用。

In this paper,spectral diagnosis incorporated with high-speed imaging technology was employed to research arc characteristic of a new proposed process of TIG welding filled with flux-cored wire.The droplet transfer modes were studied by observing the high-speed images.The spectral information was acquired by scanning the spatial points of the arc for marking some elements and the active elements K and Na of the powder were tracked to determine the distribution of the powder composition,and calculating the temperature distribution of the arc by Boltzmann plot method.The arc temperature distribution was analyzed in different droplet transfer modes.The results showed that three typical droplet transfer modes of TIG welding filled by fluxcored wire were obtained：droplet transition（2mm）,slag column transition（5mm）and bridging transition（7mm）by adjusting the horizontal distance between wire and tungsten electrode tip.The active elements such as K,Na of the powder were in the arc space above molten pool,and their distribution was affected by the horizontal distance between wire and tungsten electrode tip.The smaller distance means the closer distribution of active elements to tungsten,which leads to the tungsten electrode was polluted.The arc temperature distribution of no filler wire TIG welding was bell-shaped,and the isotherm was approximately symmetrical about the tungsten axis.Compared with no filler wire TIG welding,the distortion of arc temperature distribution was influenced by different droplet transfer modes.The temperature distribution severely distorted under droplet transfer mode accompanied with more spatters during welding.In terms of the droplet transfer mode,smaller distortion of temperature distribution and stable welding process occur in slag column transition and bridging transition which are suitable for the proposed TIG welding process.