大功率光纤激光焊焊缝跟踪偏差红外检测方法

Detection of seam tracking offset based on infrared image during high-power fiber laser welding

精确控制激光束使其始终对准并跟踪焊缝是保证激光焊接质量的前提.针对大功率(激光功率10kW)光纤激光焊接304型不锈钢紧密对接焊缝(间隙为0—0.1mm),研究一种基于红外热像的焊缝跟踪偏差检测新方法.采用红外传感高速摄像机摄取焊接区域熔池红外动态热像,分析激光束对准和偏离焊缝中心时的熔池温度分布和红外辐射特性,以熔池匙孔形变参数和热堆积效应参数作为激光束与焊缝中心偏差检测特征值,通过图像识别技术研究和分析特征值与焊缝偏差之间的关系.激光焊接试验结果表明,熔池匙孔形变参数和热堆积效应参数与焊缝偏差之间存在密切的数学关联,能有效判断和检测激光束与焊缝之间的偏差.

Seam tracking is a significant precondition to obtain good welding quality.During the laser welding,the laser beam focus must be controlled to follow the welding seam accurately.A novel approach to detecting the offset between the laser beam focus and the welding seam based on infrared image processing is investigated during high-power fiber laser butt-joint welding of type 304 austenitic stainless steel plates at a continuous wave fiber laser power of 10 kW.The joint gap width is less than 0.1 mm.An infrared sensitive high speed camera arranged in off-axis direction of laser beam is used to capture the dynamic thermal images of a molten pool.The characteristics of thermal distribution and infrared radiation of the molten pool,when the laser beam focus is deviated from the welding seam center,are analyzed.Two parameters called the keyhole morphological parameter and the heat accumulation effect parameter are defined as the characteristic values of seam tracking offset to determine the offset between the laser beam focus and the desired welding seam.Also,the image processing technique is used to analyze the infrared images of the molten pool,which indicates the presence of mathematic correlation between the defined two parameters and the seam tracking offset.The welding experiments confirm that the offset between the laser beam focus and the welding seam can be estimated by the keyhole morphological parameter and the heat accumulation effect parameter effectively.