水下湿法脉冲电流焊接熔滴过渡控制机理研究

Control Mechanism of Droplet Transfer in Underwater Wet Pulsed Current Welding

摘要:

首先分析了水下湿法焊接排斥过渡形成机理。受水环境影响水下焊接熔滴在焊接过程中受多种力综合作用，熔滴所受气体压力、气体拖曳力、等离子流力受电弧气泡生成部位及阴极斑点位置影响而波动不定，是熔滴发生排斥过渡的主要原因，表面张力阻碍熔滴侧向脱离焊丝端部，自身重力则促进熔滴脱离焊丝端部完成过渡。采用正交试验法研究了脉冲电流频率、占空比、峰值电流对水下湿法焊接成形、熔滴过渡、焊接稳定性的影响，采用焊缝余高变异系数来评估成形质量，试验结果表明，当占空比在15%~20%，峰值电流350 A，脉冲频率20 Hz左右时，焊接效果较好，通过施加脉冲电流在峰值电流阶段可以显著增强熔滴所受电磁收缩力，促进熔滴完成过渡，提高过渡频率。

Abstract:

The formation mechanism of repulsive transition in underwater wet welding was firstly analyzed. Affected by the aqueous environment, molten droplets during underwater welding are subjected to combined effect of multiple forces. The gas pressure, gas drag force, and plasma flow force acting on the droplet fluctuate dynamically with the generation location of arc bubbles and the position of cathode spots. These forces together serve as the main driving forces for the repulsive transition of the droplet. The surface tension impedes lateral detachment of the droplet from the wire tip, while gravity facilitates droplet separation from the wire tip to complete the transition. The influence of pulse frequency, duty cycle, and peak current on weld formation, droplet transfer, and welding stability in underwater wet welding was investigated using the orthogonal experimental method. The weld reinforcement variation coefficient was adopted to evaluate formation quality. The results indicate that optimal welding performance is obtained at a duty cycle from 15% to 20%, a peak current of 350 A, and a pulse frequency of approximately 20 Hz. By applying pulsed current during the peak current phase, the electromagnetic contraction force acting on the droplet is significantly enhanced, promoting droplet transfer and increasing the transition frequency.