激光焊接不锈钢微间隙焊缝偏差小波变换检测法

Detection of micro-gap seam offset based on wavelet transformation during high-power fiber laser welding

关键词:  大功率光纤激光焊接  焊缝跟踪  小波变换  偏差检测

Key words:  high-power fiber laser welding  seam tracking  wavelet transform  seam offset detection

摘要:

针对大功率(激光功率10 kW)光纤激光焊接304不锈钢间隙小于0.1 mm的紧密对接焊缝,研究一种基于小波变换的焊缝偏差检测方法. 为了分析焊缝偏差特征细节,采用红外传感高速摄像机摄取焊接区域熔池红外热像,利用小波函数对熔池图像感兴趣区域进行多尺度分解. 定义小波变换后的高频分量极值的横坐标作为匙孔形变参数,以匙孔形变参数作为特征值,分析特征值和焊缝偏差之间的关系. 结果表明,匙孔形变参数与焊缝偏差之间存在密切关联,能有效判断和检测焊缝偏差.

Abstract:

An approach of detecting the offset between the micro-gap seam and the laser beam focus based on wavelet transform was presented during fiber laser butt-joint welding of Type 304 austenitic stainless steel plate with a high power 10 kW continuous wave fiber laser. This offset is less than 0.1 mm. To study the details of seam offset characteristics, an infrared sensitive high-speed video camera was used to capture the dynamic images of the molten pools. Multi-scale decomposition was implemented to the interested area of a molten pool image by using the wavelet function. The collected horizontal coordinate of high frequency coefficient was defined as a keyhole deformation parameter, and then this keyhole deformation parameter was deemed as a keyhole eigenvalue. Through the analysis of the relationship between the eigenvalue and welding seam offset, it was found that the offset between the micro-gap seam and the laser beam focus could be estimated by the keyhole deformation parameter effectively.