大功率盘形激光焊飞溅特征分析

焊接过程的在线监控是保证激光焊接质量的关键, 为此, 首先要找到焊接过程传感特征量变化规律以及与焊缝质量间的关系. 飞溅是大功率盘型激光焊接过程中的一个重要现象, 其特征与焊接质量、焊接过程稳定性以及能量利用率等有着密切的联系. 以大功率盘形激光焊接304不锈钢为试验对象, 研究焊接过程中的飞溅特征. 在紫外波段和可见光波段应用高速摄像机摄取焊接过程中产生飞溅的瞬态特征, 通过计算机图像处理技术分析飞溅的数量、面积、行程和质心高度特征参量. 以焊件熔宽作为衡量焊接质量与焊接过程稳定性的因素, 对飞溅特征量进行线性和高次拟合, 研究飞溅特征参量的波动规律, 并与焊件熔宽的变化对比, 探索焊接过程的飞溅特征参量变化规律. 试验结果表明, 根据飞溅特征量变化规律能够对大功率盘形激光焊接304不锈钢板焊接质量做出动态评估, 为实现焊接质量的在线监控提供了试验依据.

Analysis of characteristics of spatters during high-power disk laser welding

Real-time monitoring and control of welding process is important for laser welding quality. Therefore, the variation rule of sensing characteristics of welding process and their relations to weld quality should be known. Spatter is one of the most important phenomena in high-power laser welding process. The characteristics of spatters are related to the quality and stability of welding and the utilization of the laser power. An approach to analyze the characteristics of spatters is investigated during high-power disk laser bead-on-plate welding of Type 304 austenitic stainless steel plates at a continuous wave laser power of 10 kW. An ultraviolet and visible sensitive high-speed video camera is used to capture the dynamic images of the laser welding spatters. The number, area, and ejecting distance of spatters and the centroid height of spatter images are calculated as the characteristic parameters of spatters by using the image processing technology. The weld bead width is considered as a parameter reflecting the quality and stability of welding process. The linear and the higher order polynomial curve fitting for the data of the characteristic parameters are used to study the variation rule of the characteristic parameters of spatters. In comparison of the fluctuation of the weld bead width, the correlation between the spatter characteristics and the quality and stability of welding is studied. The experimental results of actual laser welding show that the quality and stability of a high-power disk laser welding of Type 304 austenitic stainless steel plates could be monitored and estimated by analyzing the characteristic parameters of spatters, which is the foundation for monitoring and control of welding quality in real time.