高效MAG焊接熔滴过渡行为及交变磁场控制试验分析

探索更加高效的焊接方法和工艺是当前国际焊接界一个热点课题，而增大焊接电流和焊丝伸出长度可直接提高MAG焊焊接效率. 文中对商用MAG焊机进行改造，使送丝速度达到50 m/min，焊接电流提升至500 A以上，以进一步提高焊接效率. 但是熔滴旋转射流过渡的形成，导致电弧不稳，飞溅增大，因而采用外加交变磁场来改善电弧形态和熔滴过渡行为. 通过焊接工艺试验，分析了焊接电流对焊接飞溅率和金属蒸发速率的影响规律，研究了交变磁场对熔滴过渡行为和焊缝成形的作用. 结果表明，外加低频交变磁场可以有效提高大电流下电弧挺度和稳定性，缩短液流束长度，减小液尖偏斜程度，进而改善焊缝成形，大幅度提高焊接效率.

Droplet transfer behavior and alternating magnetic field controlled experimental study of high efficiency MAG welding

Developing more efficient welding methods and processes is a hot topic in the international welding industry, and increasing welding current and extension length is a direct approach to improve melting efficiency of MAG welding. Through improving commercial MAG welding machine, wire feeding speed can reaches 50 m/min, and the welding current is up to 500 A or more so as to further enhance welding efficiency. But the formation of rotating spray transfer of droplet, resulting in welding arc instability and lots of spatters, thus an alternating magnetic field is applied to control the arc morphology and droplet transfer behavior. With the welding experiment, the influence of welding current on spatter rate and metal evaporation rate was analyzed and the droplet transfer behavior and weld appearance under alternating magnetic field was studied. The results show that under high welding current with low frequency magnetic field can effectively enhance the arc stiffness and stability, shorten the length of liquid stream and reduce the deflection of fluid tip, improve the weld appearance, and then greatly increase the welding efficiency.