对于复杂微细、错边量小的激光焊接拼缝测量,现有的视觉传感器方法不能稳定、可靠地提取出拼缝的中心位置、拼缝宽度等信息。为此,提出了基于微景深的激光焊接对接拼缝测量方法,该方法采用高倍光学放大镜头、工业CCD(Charge Coupled Device)/CMOS(Complementary Metal-Oxide-Semiconductor Transistor)相机和LED(Light-Emitting Diode)外部照明装置,以光学成像光轴与被测表面法矢呈45°的方式,组成的对接拼缝的非接触测量系统,既解决了显微放大时景深很小、测量范围小的问题,又解决了狭窄拼缝高光学放大倍数拼缝检测的难题。实验结果表明,该系统可快速准确地提取出拼缝中心坐标、拼缝宽度以及拼缝局部表面法矢。拼缝宽度测量精度优于5 μm,拼缝中心测量精度优于6 μm,可识别的最小拼缝宽度为0.02 mm,完全满足激光焊接对接狭窄拼缝的检测与自动跟踪的要求。

For the seam feature measurement of the tight butt joint without misalignment in laser welding, current vision sensor cannot obtain the seam gap width and seam position stable and reliable enough. In this paper, a seam measurement method based on the micro depth of field is proposed. A hight optical magnification lens, a CCD(Charge Coupled Device)/CMOS(Complementary Metal-Oxide-Semiconductor Transistor) camera and an external LED(Light-Emitting Diode) lighting unit are used to constitute the non-contact measurement system. The measurement system can be used for the tight butt joint in laser welding. The angle between the seam surface and the optical axis of the camera is about 45°. The installation method solves the problem that the depth of field and the field of view are too small to measure the tight butt joint with the multi-time magnification image measurement system. Experiments indicate that the measurement system can obtain the seam gap width and seam position stable and correctly. With this measure method, the seam surface normal vector also can be measured. The measurement accuracy for the seam gap width and seam position is 5 μm and 6 μm, respectively. Furthermore, the narrowest welding seam gap that can be measured is 0.02 mm, which fully satisfies the demand of the seam measurement in laser welding.