微间隙焊缝磁光成像检测方法

A method to detect micro weld gap based on magneto-optical imaging

关键词:  磁光成像  微间隙焊缝  激光焊接

Key words:  magneto-optical imaging  micro weld gap  laser welding

摘要:

针对激光焊接紧密对接微间隙(0~0.1 mm)焊缝,研究一种基于法拉第磁光效应成像的焊缝检测新方法.以碳钢平板对接激光焊为试验对象,采用磁场激励器使焊件感应磁性并在焊缝处改变磁场分布,磁光传感器置于待测焊缝上方,不同磁场强度将导致磁光传感器偏振光不同角度的旋转,形成反映焊缝位置特征的磁光图像.对焊缝磁光图像进行滤波去噪、灰度转换以及形态学等处理,快速准确地提取出焊缝中心位置.结果表明,磁光图像能够有效反映微间隙焊缝位置,可以获得较高的测量精度,为解决微间隙焊缝检测和跟踪问题提供了一条有效途径.

Abstract:

A new method was developed to detect the micro weld gap (0-0.1 mm) during laser welding,based on Faraday magneto-optical effect imaging. During laser butt-welding of carbon steel,a magnetic excitation device was used to magnetize the weldment. It was found that the magnetic field distribution in the weld zone was different from other zones. A magneto-optical sensor was placed upon the magnetized weldment to obtain the magneto-optical images of the weld. Different magnetic field intensities would lead to rotation of the polarized light of magnetooptical sensor in different directions,and the magneto-images consisting of the joint position feature could be captured. By using image-processing methods, such as median filtering, grayscale transform,threshold segmentation and morphology,the micro weld gap center could be extracted rapidly from a magnetooptical image. The experimental results show that the magnetooptical images could effectively and accurately reflect the position of micro weld gap. The proposed method provides a novel approach for automatic identification and tracking of the micro weld gap during laser welding.