Elucidation of arc coupling mechanism in plasma-MIG hybrid welding process through spectroscopic measurement of 3D distributions of plasma temperature and iron vapor concentration
Elucidation of arc coupling mechanism in plasma-MIG hybrid welding process through spectroscopic measurement of 3D distributions of plasma temperature and iron vapor concentration
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DOI：
10.1016/j.jmapro.2022.04.002
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发表时间：
2022-05
影响因子：
6.2
通讯作者：
K. Ishida;S. Tashiro;K. Nomura;Dongsheng Wu;Manabu Tanaka
中科院分区：
文献类型：
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作者：
K. Ishida;S. Tashiro;K. Nomura;Dongsheng Wu;Manabu Tanaka
通过对等离子体温度和铁蒸气浓度三维分布的层析光谱测量，阐明了等离子体-铁蒸气复合焊接中电弧耦合现象的机理。电弧耦合强烈地依赖于电弧电流波形，因此使用直流斩波电流和脉冲斩波电流的情况下进行比较。结果，在使用DC直流电流的情况下，两个电弧规则地连接，因为在具有足够导电性的两个电弧之间广泛地形成高温区域，保持电弧之间的电流传导。在脉冲直流情况下，两电弧仅在脉冲直流上升段强连接。在其他时间段，两条弧都是弱连通或断开的。弧连接被认为是由两个弧的刚度和偏转之间的平衡来控制的。在采用脉冲整流的情况下，虽然脉冲整流电流与上升段的情况相似，但在脉冲整流电流的下降段，两个电弧并不连接。在上升段，由于热箍缩效应，电弧被认为是收缩的，从而增加了电流密度，这增强了电弧的刚度，以促进电弧连接。相反，在下坡持续时间中，脉冲电弧电流密度变得较低，这使电弧向后偏转以断开电弧。在接弧过程中等离子体电流增加了35 A，使喷嘴下方等离子体电弧温度提高了1000 K。结果表明，电弧耦合影响等离子弧作用于小孔内壁的电弧压力和剪切力的分布，从而控制小孔的稳定性和熔池的形成过程。
This study aims to clarify the mechanism of arc coupling phenomenon in plasma-MIG hybrid welding through the tomographically spectroscopic measurement of 3D distributions of plasma temperature and iron vapor concentration. The arc coupling strongly depends on arc current waveforms, so both the cases using DC MIG current and pulse MIG current were performed for the comparison. As a result, in the case using DC MIG current, two arcs were regularly connected, because the high temperature region between two arcs with an enough electrical conductivity was widely formed, retaining the current conduction between arcs. In the case using pulse MIG current, the two arcs were strongly connected only in the upslope duration of pulse MIG current. Both arcs were weakly connected or disconnected in other durations. The arc connection is thought to be governed by the balance between the stiffness and deflection of both arcs. In the case using pulse MIG current, two arcs were not connected in the downslope duration of pulse MIG current, although the pulse MIG current was similar with that in the upslope duration. In the upslope duration, the MIG arc is thought to be constricted because of the thermal pinch effect to increase the current density, which enhances the stiffness of MIG arc to prompt the arc connection. In contrast, the pulse MIG current density becomes lower in the downslope duration, which deflects the MIG arc backward to disconnect the arcs. The plasma current increased by 35 A during the arc connection, which increased the plasma arc temperature below the nozzle by 1000 K. The result implies that the arc coupling affects the distributions of the arc pressure and shear force by plasma arc acting on the keyhole inner wall, governing the keyhole stability as well as the weld pool formation process.