焊接电弧形貌判别模型及钨极高度的影响规律

Automatic recognition and control of welding arc morphology as a function of the welding current and the tungsten electrode height

在不同的焊接工艺参数下,电弧具有不同的几何形貌,焊接工艺参数的改变会实时地引起电弧形貌发生变化。借助高速摄像和图像处理技术,通过将弧柱边缘像素点的坐标从图像坐标系转换至以弧柱质心为原点的极坐标系,该文提出了一种基于极坐标的电弧形貌判别模型,实现了电弧形貌的有效识别,并研究了不同焊接电流下电弧形貌与钨极高度的定量关系。试验结果表明:在不同的焊接电流和钨极高度下,电弧存在扁锥形、钟罩形、长锥形和长条形4种典型形貌。电弧呈现钟罩形时,电弧的横向摆动幅度较小,有利于焊接电弧的稳定燃烧和保证焊缝成形质量。随着焊接电流的变化,不同电弧形貌对应的钨极高度范围也会发生改变。基于电弧形貌的钨极高度控制策略,为自动化焊接中实时控制钨极高度提供了新途径。

A welding arc has very different geometric morphologies depending on the welding process parameters that can change during the weld. High speed photography and image processing were used to develop a discriminating model to evaluate the arc morphology while welding using a polar coordinate system. The model was then used to study the quantitative relationship between the arc morphology and the tungsten electrode height for various welding currents. The experimental results show that various welding currents and tungsten electrode heights lead to four typical arc morphologies with oblate conical shapes, bell jar shapes, long conical shapes and long strip shapes. The range of tungsten electrode heights corresponding to each arc morphology were found to vary for different welding currents. With the bell jar shaped arc, the arc has smaller lateral oscillations, which gives a more stable welding arc and better welding seam quality. A control strategy was then developed based on the arc morphology to control the tungsten electrode height for real-time control of the tungsten electrode height during automatic welding.