单道叠层堆焊中电弧及熔滴过渡行为检测和分析

Detection and Analysis of Arc Shape and Droplet Transfer Behavior in Laminated Single Track Bead Welding

弧焊快速成型中电弧形态及熔滴过渡行为对焊接过程的稳定性和构件成型性有较大影响。对平特性焊接电源单道叠层堆焊时的电弧形态及熔滴过渡行为的变化,建立了MIG单道叠层堆焊实验系统,并利用高速摄像采集了第一层和叠层焊接时的电弧形态和熔滴过渡行为,分析了叠层焊接时电弧长度较第一层的电弧长度出现明显缩短的原因,解释了叠层焊接过程中熔滴过渡比第一层焊接时困难的机理。结果表明:叠层焊接时电弧缩短是因为电弧形态变化使电弧特性曲线发生变化,所以不会出现电弧自调节现象,而干伸长增加,干伸长分压变大,其共同作用导致弧压变小。叠层焊接时电流的减小,导致电弧总机械力减小,使熔滴过渡频率下降,熔滴尺寸增大。

Arc shape and droplet transfer behavior have great influence on the stability of welding process and the formability of welding products in the process of welding. To study the variation of arc shape and droplet transfer behavior in the process of laminated single track bead welding with flat output characteristic power source,the laminated single track bead welding experiment system MIG was established. The arc shape and droplet transfer behavior of the first layer and laminated layer were acquired by high-speed video acquisition system. The reason why the arc length of other layers would become more shorter than the first layer in the welding process was analyzed. The mechanism that droplet transfer in laminated layer was more difficult than in the first layer was explained.The results show that： the arc shortening in the process of laminated layer welding is caused by the change of arc static characterization, the arc self-adjustment is not worked to decrease the wire extension, and means voltage in it is increased, so the arc voltage is decreased. The total mechanical force acting on arc is decreased because of the decrease of welding current which causes the droplet transfer frequency declines and the drop size increases.