【作者】 沈莹吉；

【导师】 王克鸿；

【作者基本信息】 南京理工大学 ， 材料加工工程， 2007， 硕士

【摘要】 本课题的目的在于从清晰的熔池图像中获取反映焊接质量的特征信息，为基于视觉的焊接过程质量控制提供关系模型。针对MAG焊电弧光谱特点，采用被动式视觉传感方法，利用CCD摄像机配合近红外复合滤光系统消除弧光干扰，获取MAG焊熔池图像。采用数字图像处理技术对典型熔池图像进行了灰度特征信息分析，提出了利用熔池图像灰度均值来研究焊接过程的新思路，得出图像灰度均值与焊接规范相关、灰度均值波动大小反映了过程稳定性的结论。以熔池外轮廓为研究对象，建立了熔池视觉图像几何参数指标体系，利用几何参数指标定量分析了熔池边缘形态与焊接稳定性关系；以熔池内部为研究对象，提取出电弧区和熔渣区轮廓，为进一步研究熔池内部特征信息与焊接质量关系奠定了基础。从MAG焊焊接缺陷产生的机理及熔池流态出发，采用同步对比试验，结合熔池几何参数，研究了熔池图像特征与焊接缺陷的映射关系，提取出气孔、焊塌、焊穿、焊偏等焊接缺陷所对应的熔池图像特征及熔池图像几何参数变化规律。试验表明：一种图像特征可能预示多种焊接缺陷的产生，一种焊接缺陷可能有多种图像特征显示；通过熔池视觉图像特征判断焊接缺陷具有良好的可行性，为基于视觉传感的焊接缺陷自动在线预测提供了技术依据及其相关模型。更多还原

【Abstract】 The purpose of the subject was to acquire the useful quality characteristic informationfrom the weld pool image, which built a good foundation for the welding quality controlbased on vision sensing.A passive vision sensing system for taking the image of MAG welding pool had beenset up in this paper. CCD and the near-infrared compound filters system were used toeliminate the arc disturbance and a lot of clear images were obtained. Image-processingsoftware was used to analyse the gray character. Gray mean was put forward to study theprocess of MAG welding. Taking the weld pool outline as object, the weld pool geometryparameter system was established and the relationship between the weld pool edgecharacter and the welding stability was analyzed. Taking the interior pool as the object, thearc and the molten-slag’s contours were extracted.The relationship between image characteristic information and the weld defect wasstudied by sync contrast experiments. The visual characters of the pore, weld collapse andthe other defect were extracted. The experiments approved that one kind of image maypredicate several kinds of welding defect, one kind of welding defect may also showedseveral kinds of image characters. Experimental results show that it is feasible to judge thedefect by visual characters which offered a technological foundation for automaticidentification of welding defect on the base of vision sensing.更多还原