外加磁场对钨极电弧压力分布与焊缝成形的影响

Effect of External Magnetic Field on Tungsten Arc Pressure Distribution and Weld Formation

采用小孔法分别测量了直流磁场和交变磁场作用下的钨极电弧压力分布,并采用高速摄像采集焊接电弧形态。结果表明:直流磁场作用使钨极电弧中心压力减小,而且随着磁感应强度的增加电弧中心压力不断减小,并在200 Gs时出现负压;交变磁场作用下,随着交变磁感应强度增加和频率降低,电弧中心峰值压力下降,周边上升,这与其电弧形态顶部阴极收缩,底部阳极扩张相对应。交变磁场强度和频率通过影响电弧压力和电弧搅拌作用,进而影响焊缝成形,在磁场频率500 Hz以内,磁场频率越大,磁感应强度越小,深宽比越大。

Small hole method was used to measure the arc pressure distribution of tungsten arc with external DC and AC magnetic fields on the surface of the tungsten electrode. A high-speed camera was used to capture the shape of the arc. The results show that DC magnetic field reduces the pressure of the arc center. The arc center’s pressure decreases as the magnetic flux density increases, when the magnetic field intensity reaches 200 Gs, a negative pressure occurs at the arc center. Under the action of AC magnetic field, as the intensity of the alternating magnetic field increases and the frequency decreases, the peak pressure at the arc center decreases, and the arc periphery’s pressure rises, which corresponds to contraction of the arc shape at the top cathode and expansion of the bottom anode. The intensity and frequency of the alternating magnetic field affect the formation of the weld through changing the arc pressure and arc agitation. Within the magnetic field frequency less than 500 Hz, the bigger the magnetic field frequency is and the smaller the magnetic flux density is, the bigger the depth to width ratio is.