大功率盘形激光焊接过程等离子体图像特征分析

Analysis of characteristics of plasma image during high-power disk laser welding

研究一种基于等离子体图像特征的大功率盘形激光深熔焊质量分析及检测的新方法.以大功率盘形激光焊接Type 304不锈钢板为试验对象,应用高速摄像机摄取焊接过程中的等离子体图像,通过图像处理技术提取等离子体的面积和高度特征.以熔宽作为衡量焊接过程稳定性的因素,对比焊接过程中等离子体图像和焊接试件的熔宽变化,研究相邻等离子体图像的面积变化值和高度变化值在不同焊接质量区域中的平均值和基于不同阈值下所占的百分比,探索判定焊接过程质量稳定性的特征参量的统计规律.结果表明,所提出的方法能够对大功率盘形激光焊接Type 304不锈钢板焊接质量做出动态评估.

A new approach for detecting and analyzing the deep welding quality in high-power disk laser welding based upon the plasma plume images is presented.During the laser butt-joint welding of 304 austenitic stainless steel plate with a high power 10 kW disk laser,an ultraviolet and visual sensitive high-speed video camera was used to capture the dynamic images of the plasma plume.The area and height of a plasma image were calculated as the characteristic parameters of plasma image using the image processing techniques.The weld bead width was defined as the parameter reflecting the stability of welding process.Moreover,the variation in the weld bead width and the plasma images in the welding process were monitored to research the correlation between the characteristics of the plasma image and the welding stability.To obtain the statistics of the characteristic parameters of plasma images that reflect the welding stability,the average and the percentage with different threshold values about the fluctuation of consecutive frames images for the plasma area and height at different parts of weld bead were studied.The actual laser welding experimental results showed that the stability of a high power disk laser welding process could be monitored and estimated by the defined characteristic parameters of the plasma images.