CO_2激光焊同轴视觉系统及熔透状态检测的研究

Coaxial Vision Sensing System and Detection of Penetration Status in CO_2 Laser Welding

本文对CO2 激光深熔焊的CO2 激光、等离子体辐射和熔池辐射光谱进行了分析和实验研究 ,在此基础上研制成功了基于具有特殊功能镀膜的分光镜、综合滤光系统和CCD摄像机的CO2 激光焊同轴视觉系统 ,解决了熔池图像同轴检测和等离子体强辐射干扰等关键技术 ,较清晰地实时显示俯视小孔穿透状态的二维图像。发现了焊接过程中焊缝熔透状态由“未熔透”或“仅熔池透”变为“适度熔透 (小孔穿透 )”时小孔图像变化的规律 ,获得了理想熔透状态的图像特征 ,为进一步进行熔透闭环控制打下了基础。

A coaxial vision sensing system for CO_2 laser welding,consisting of a dichroitic mirror with special functional films,a set of spectral filters and a CCD camera,is designed based upon the analysis and experimental study on the spectrum of CO_2 laser,plasma and weld pool emission. The key technology for coaxial monitoring of the weld pool and eliminating the interference of the plasma emission is developed. The two-dimensional image of the keyhole is obtained clearly in downward coaxial direction for displaying the keyhole penetration status. The variation of the keyhole images as the penetration status transits from 'partial penetration' or 'weld pool penetration' to 'moderate full penetration' is investigated,and the image characteristic for ”moderate full penetration” is obtained. Closed-loop control of penetration can be expected to be realized based on the above result.