基于电弧图像的脉冲TIG焊电弧形态及特征温度演变规律

Arc shape variations and characteristic temperatures of pulsed TIG welding arcs based on observed arc images

脉冲电流钨极惰性气体(tungsten inert gas,TIG)保护电弧焊广泛应用于高品质焊接制造。研究电弧形态、灰度和温度等特征参数随脉冲电流的变化规律,有助于更深入地理解脉冲TIG焊的电弧动态物理特性,更好地评判焊接过程的稳定性和控制焊缝成形质量。该文通过同步采集焊接过程的脉冲电流及对应的电弧图像,借助于图像处理和标准温度法计算求解了脉冲TIG焊的电弧形态、灰度及特定位置的温度,分析了其随脉冲电流周期性变化的规律。试验结果表明,脉冲TIG焊的电弧形态、灰度、特定位置的温度等特征参数与脉冲电流的变化同步,同步精度在0.1 ms以内。在脉冲电流前后沿的电流突变过程中,电弧在电流增加时的形态扩张和温度上升速度快于电流减小时的形态收缩和下降速度。在钨极下方1 mm处,电弧温度在脉冲电流增加时的平均上升速度为11613 K/ms,在脉冲电流减小时的平均下降速度为5710 K/ms。距离钨极越近,电弧灰度在电流突变前后的变化越小,但电弧温度的变化越大。

Pulsed current tungsten inert gas(TIG)shielded arc welding is widely used in high quality welding.The arc characteristics,including the variations of the arc shape,gray-scale and temperature with the pulsed current,are studied here to understand the dynamic physical characteristics of pulsed TIG welding arcs,especially the welding stability and the control of the weld seam quality.The pulse current and corresponding arc images were acquired synchronously during the welding process.Image processing using the Fowler-Milne method was used to characterize the arc shape,gray-scale and temperatures at specific positions within the pulsed TIG welding arc to analyze their periodic variations.The experimental results show that the arc characteristic parameters at specific positions within the pulsed arc are synchronized with the current variations to within 0.1 ms.The arc expands and the arc temperature quickly rises as the current increases along the front edge of the pulse and then the arc contracts and the arc temperature falls as the current decreases.The arc temperature 1 mm below the tungsten electrode rises at a rate of 11613 K/ms as the current increases and decreases at a rate of 5710 K/ms as the current decreases.The arc gray-scale changes less closer to the tungsten electrode before and after the current changes,but the arc temperature changes are greater.