基于光谱诊断的VPPA-MIG复合电弧耦合机理分析  

Analysis of VPPA-MIG Hybrid Arc Coupling Mechanism Based on Spectral Diagnosis

作　　者：韩蛟 韩永全[1] 洪海涛[1] 孙振邦[1] HAN Jiao;HAN Yongquan;HONG Haitao;SUN Zhenbang(Engineering Research Center of“Advanced Light Metal Material Development and Processing Protection”of Ministry of Education,Inner Mongolia University of Technology,Huhehot,010051,China)

机构地区：[1]内蒙古工业大学教育部“先进轻金属材料开发与加工防护”工程研究中心,呼和浩特010051

出　　处：《焊接学报》2023年第11期104-109,I0008,I0009,共8页Transactions of The China Welding Institution

基　　金：国家自然科学基金(52265054);内蒙古自治区科技计划项目(2020GG0313);内蒙古自治区自然科学基金项目(2022Z D03);内蒙古自治区自然科学基金博士基金项目(2021BS05016)。

摘　　要：铝合金变极性等离子弧(variable polarity plasma arc,VPPA)-MIG复合焊中,VPPA焊接电流为130 A,MIG焊接电流200 A时,MIG电弧等离子体在电流基值期间偏向正极性(钨极接负)阶段的VPPA等离子体并与之相连,并未与反极性阶段(钨极接正)的VPPA等离子体产生连接,且基值阶段的MIG电弧电压在VPPA正极性时更低.为了阐明上述行为机理,对复合电弧进行了光谱诊断.基于Boltzmann图解法和Stark展宽法计算了VPPA-MIG复合电弧位于试板上方2.5 mm处,VPPA区,耦合区及MIG区中心位置的平均温度和电子密度,证明了上述位置等离子体的平均状态处于局部热力学平衡状态.基于发射系数与等离子体温度的关系,利用Ar794.8 nm窄带滤波结合高速摄像的方法,发现VPPA在反极性期间的高温区面积大于其在正极性期间的高温区面积.而且VPPA中的Al 396.1 nm谱线在反极性期间,辐射强度更高,范围更广.由此证明了复合焊中基值阶段的MIG电弧电压的降低,主要来自于阴极压降而非弧柱压降.In the VPPA(variable polarity plasma arc)-MIG hybrid welding of aluminum alloy,when the welding current of VPPA is 130 A and the MIG welding current is 200 A,the MIG arc plasma is biased towards and connected with the VPPA plasma in the positive(tungsten electrode is negative)stage during the current base period,and does not connect with the VPPA plasma in the reverse polarity stage(tungsten electrode is positive),and the MIG arc voltage in the base stage is lower when the VPPA is positive.In order to clarify the above behavior mechanism,the hybrid arc was diagnosed by spectroscopy.Based on the Boltzmann diagram method and Stark broadening method,the average temperature and electron density of the VPPA-MIG hybrid arc at 2.5 mm above the test plate,the VPPA region,the coupling region,and the center of the MIG region are calculated.It is proved that the average state of the plasma at the above position is in a local thermodynamic equilibrium state.Based on the relationship between the emission coefficient and the plasma temperature,it is found that the high-temperature area of VPPA during the negative polarity period is larger than that during the positive polarity period by using Ar 794.8 nm narrow-band filtering combined with a high-speed camera.Moreover,the Al 396.1 nm spectral line in VPPA has higher radiation intensity and wider range during the reverse polarity period.It is proved that the decrease of MIG arc voltage in the base stage of hybrid welding mainly comes from cathode voltage drop rather than arc column voltage drop.Highlights:(1)It is proved that the average state of VPPAMIG hybrid arc is in local thermodynamic equilibrium.(2)The temperatures of different regions of VPPA-MIG hybrid arc are calculated and analyzed,and the mechanism of arc behavior is explained.

关 键 词：VPPA-MIG复合焊接 光谱诊断 局部热力学平衡状态 电弧耦合机理 

分 类 号：TG403[金属学及工艺—焊接]