基于视觉图像传感的精密脉冲TIG焊焊缝跟踪

针对某复杂曲面薄壁不锈钢工件精密脉冲TIG焊中的焊缝跟踪问题 ,本文研究了一种基于视觉传感的高精度、高实时性焊缝跟踪技术。根据脉冲TIG焊的工艺特点 ,该技术通过选择特定波长的滤光片及合理的曝光时刻 ,采用工业CCD摄像机获取可直接分辨出焊缝、熔池和钨极的清晰、放大的焊接区图像。采用VC语言设计的图像处理算法 ,可以快速准确地识别出焊缝中心线 ,提取钨极偏离焊缝中心线的方向和距离 ,驱动步进电机调节焊炬位置 ,实现高精度、高实时性的焊缝跟踪。试验结果表明 ,该技术的单幅图像处理周期小于 12 0ms,能实现焊炬运动方向与焊缝偏差角小于 3 0°的焊缝跟踪 ,满足了复杂曲面的薄壁不锈钢工件的精密焊接要求。

A Visual Sensor Based Weld Seam Tracking Method for Precision Pulse TIG Welding

In order to solve the weld seam tracking problem in the pulse TIG welding process of some thin stainless steel workpiece with complicated curved surface,a high precision and rapidly responsing speed seam tracking method based on visual sensor has been developed in this paper.According to the process characteristics of pulse TIG welding,special wavelength filter and reasonable exposure schedule have been selected,the clear and amplified welding image (from which weld seam,weld pool and tungsten electrode could be identified directly) could be acquired with industrial CCD camera.Then,an image processing algorithm has been programmed with Visual C language.With this algorithm,the central line of weld seam could be detected rapidly and precisely,the direction and distance which the tungsten electrode deviates from the central line of weld seam could be calculated out,the step motor has been driven to adjust the position of welding torch.Therefore,the precise and real time weld seam tracking has been realized.Experimental result shows that,processing time for single image is less than 120 ms,the seam tracking could be carried out if the angle between welding direction and weld seam is no more than 30°.Finally,the thin stainless steel workpiece with complicated curved surface has been successfully welded using this method.