变极性等离子弧焊研究进展

Progress in variable polarity plasma arc welding

关键词:  变极性等离子弧焊  电弧稳定性  阴极清理  小孔检测

Key words:  variable polarity plasma arc welding  arc stability  cathodic cleaning  keyhole detection

摘要:

变极性等离子弧焊的优点在于能够灵活调节特征工艺参数如电流频率、正负半波电流幅值及导通时间比,以满足铝合金焊接时的阴极清理和形成穿孔焊。介绍了国内外在实现变极性电流波形、电弧稳定性、阴极清理机理、小孔信号检测等方面的研究现状。指出保证前后级同步是双逆变电路形式的技术关键,双通道形式可克服主、维弧干涉并降低钨电极烧损。溅射、电介质击穿及瞬时熔化和蒸发是目前解释阴极清理机理的主要理论,重要的是工艺参数对清理的影响规律。近年来又出现了几种新的小孔检测方法,而正面检测及多传感信息融合仍是其主要发展方向。

Abstract:

The advantage of variable polarity plasma arc welding is that the characteristic parameters such as the frequency, current amplitude and DCEN/DCEP ratio can be adjusted at will to meet the need of cathodic cleaning and keyholing. The status of realization of variable polarity current waveform, arc stability, cathodic cleaning mechanism and keyhole detection is introduced in this paper. To ensure the synchronization between primary and secondary circuit is the key of dual-inverter. Dual-passage can eliminate the interference between main arc and pilot arc, and decrease the deterioration of tungsten electrode. Ion sputtering or ion bombardment, dielectric breakdown and momentary melting and evaporating are the main theories of cathodic cleaning mechanism. It is more important to master the regularity of cleaning. Of all recent developed keyhole detection methods, front side detection and multi-sensing information is still the leading direction.