钨极惰性气体保护焊熔池三维自由表面特征参数的激光视觉测量

Measurement of Characteristic Parameters of Three Dimensional Weld Pool Surface in Tungsten Inert Gas Arc Welding Based on Laser-Vision

针对现有的钨极惰性气体保护焊熔池三维自由表面测量方法难以应用于强弧光、高温辐射、液态金属表面镜面反射等问题,提出一种激光视觉测量法.利用小功率点或线阵模式结构激光照射覆盖整个熔池表面,采用高速摄像机实时采集经熔池液态金属表面反射畸变的激光图像.设计图像处理算法提取成像激光点位置坐标,建立与投射激光点位置坐标的空间转换数学模型,离线获得熔池三维自由表面的几何特征参数值,对比实测凝固熔池表面对应参数值发现,所提取的几何特征参数值与实测值吻合较好,熔宽、长度和凸度误差分别为0.8%、0.6%和4.7%,证明激光视觉法能够实现熔池自由表面三维信息的动态测量,为采用几何特征参数调整熔池自由表面形貌变化控制焊缝成形及缺陷提供一种新方法.

Aimed at the problems in measuring the three dimensional weld pool surface in tungsten inert gas arc welding in existing methods, which are hardly applied in the strong arc light, high temperature radia- tions and specular refection. A novel method named laser-vision was developed, and the measurement sys- tem was established. The experiments with laser dot matrix and parallel lines pattern were performed and the reflected laser distorted images were captured by a high speed camera. The reflected laser dot coordi- nate and its transfer model between projected laser dot coordinate were extracted and established, respec- tively. The geometric parameters of the weld pool surface were obtained offline. The comparison of the ex- tracted and measured result shows that the proposed method can successfully measure the three dimension- al information of the weld pool surface and the extracted results coincide with the actual measurement well. The error of width, length and convexity is 0.8% ,0.6% and 4.7%, respectively. This paper pro- vides a new method for control of 3D weld pool surface in real-time.