为了研究离焦量对激光填丝焊熔滴过渡及相关特征的影响,获得稳定过渡模式,借助高速摄像系统观察了不同离焦量下的熔滴过渡行为,并将其分为液桥过渡、混合过渡和滴状过渡3种类型进行了分析。结果表明,离焦量为-1mm和+3mm时的液桥过渡模式可以保证焊接过程的稳定性,获得的焊缝质量良好,焊缝截面无气孔等缺陷；而离焦量为+5mm时的过渡模式为滴状过渡,此时焊接稳定性最差,焊接过程中匙孔会完全闭合,焊缝表面成形不规则,焊缝截面底部出现大的气孔。该研究结果对实际生产有指导作用。

In order to study effect of defocus on droplet transfer and related characteristics of laser welding with filler wire, and achieve stable droplet transfer mode, a high speed camera system was used to observe droplet transfer under different defocus parameters. Droplet transfer was divided into three kinds: liquid bridge transfer, mixed transfer and drop transfer. The results show that, liquid bridge transfer mode with defocus of -1mm and +3mm could improve the stability of welding process with good quality, such as the weld cross section without porosity. For the drop transfer mode with defocus of +5mm, the welding stability is the worst. During the welding process, keyhole is completely closed, the surface of weld bead is formed irregularly, and the large pores appear at the bottom of the weld corrosion-face. The research results have guiding effect on actual production.