新型变极性等离子弧焊设备的研究

Study on a New Kind of Variable Polarity Plasma Arc Welding Equipment

研究并设计了一种用于铝镁金属及其合金焊接的新型不对称变极性等离子弧焊设备．交变方波的正、负半波电流分别由两台独立的直流电源供电．与传统变极性等离子弧焊设备最大的不同是在焊接过程中，钨电极在极易烧损的负半波不接正极，因而使电极尖端的形状、尺寸得以长时间保持，大大提高了焊接过程的稳定性．另外，由于负半波主弧电流与维弧电流“各行其道”，从而避免了传统变极性等离子弧焊过程中主、维弧相互干涉，导致电弧不稳的现象．

This paper introduces a new kind of variable polarity plasma arc welding (VPPAW) equipment used for welding aluminium, magnesium and their alloys. The current of the positive and negative half waves of the alternative rectangular waves are supplied by two independent DC power sources. Compared with the traditional VPPAW, the main difference lies in that tungsten electrode is not linked with anode when current is in negative half wave during welding process, therefore, the shape and size of the electrode tip can be maintained for a longer time, and the welding stability is improved. In addition, the negative half wave current for main arc is independent of the current for pilot arc, that avoids the current interference between main arc and pilot arc and makes the welding arc stable.