Abstract:

For the one droplet per pulse transfer of pulsed metal active gas(MAG) welding,a novel pulsed waveform with backward median phase was presented. The effect of backward median current and backward median time on the welding process was studied. The optimum backward median current and backward median time were found by experiment when welding steel.The experimental results demonstrate that when the backward median current is in an optimum value range, the welding effect is satisfactory, and when the backward median current is small or large,the welding effect is similar to normal pulsed MAG welding process,the sense of backward median current is not obvious.On the basis of defining the backward median current as an optimum value,the welding effect is satisfactory when the backward median time is in an optimum value range.The instantaneous short circuit occurs when the backward median current is small or large. By adjusting the backward median current and backward median time, it can enhance the controllability of droplet transfer and get one droplet per pulse transfer,and the weld seam formation will be pretty good.

Key words: pulsed metal active gas welding, droplet transfer, pulsed waveform, backward median phase

摘要：

针对脉冲MAG焊一脉一滴熔滴过渡过程的控制，提出后中值脉冲新工艺方法，分析了后中值电流及后中值时间对脉冲MAG焊接过程的影响规律。采用后中值脉冲工艺方法对低碳钢进行焊接工艺试验，确定了最佳的后中值电流和后中值时间。试验结果表明：后中值电流为一理想值范围时焊接效果较好，后中值电流太小或太大时焊接过程能稳定，但其焊接过程类似于无中值脉冲时的焊接过程，失去后中值脉冲工艺的意义；在确定了后中值电流为给定的理想值的基础上，后中值时间为一理想值范围时焊接效果较好，后中值时间太小或太大时焊接过程不稳定，会产生瞬时短路和断弧现象。合理地设置后中值电流和后中值时间，有利于控制熔滴过渡，实现一脉一滴过渡，获得的焊缝质量好、成形美观。

关键词: 脉冲MAG焊, 熔滴过渡, 脉冲波形, 后中值