基于熔池光信号的激光粉末床熔融沉积缺陷在线监测与诊断(特邀)  

In⁃Situ Monitoring and Diagnostics for Deposition Defects in Laser Powder Bed Fusion Process Based on Optical Signals of Melt Pool(Invited)

作　　者：陈香媛 韦辉亮 刘婷婷[1] 张凯[1] 李建森 邹志永 廖文和[1] Chen Xiangyuan;Wei Huiliang;Liu Tingting;Zhang Kai;Li Jiansen;Zou Zhiyong;Liao Wenhe(School of Mechanical Engineering,Nanjing University of Science and Technology,Nanjing 210094,China)

机构地区：[1]南京理工大学机械工程学院,南京210094

出　　处：《中国激光》2024年第10期138-151,共14页Chinese Journal of Lasers

基　　金：国家重点研发计划(2022YFB4600800);国家自然科学基金(52322509,52175330);江苏省自然科学基金(BK20230034)。

摘　　要：在激光粉末床熔融(LPBF)成形过程中,铺粉异常导致的沉积缺陷会严重影响成形零件的表面及内部质量,但目前缺乏针对性的在线监测与诊断方案。采用光电探测器和高速相机在线监测成形过程中的光强和熔池面积信号,探究不同粉末厚度条件下熔池尺度光信号的变化规律,实现对零件质量的初步诊断。研究结果表明,粉末厚度的异常增加会导致零件熔化状态出现波动,并最终导致严重的球化。表面粗糙度从正常打印状态的5μm显著增加至100μm以上,同时在零件内部形成了未熔合孔隙缺陷。阐述了粉末厚度对沉积缺陷的影响机制,深入分析了光强与熔池面积的特征及其相互关系,提出了一种基于阈值百分比诊断沉积缺陷的信号监测方法。Objective Laser powder bed fusion(LPBF)is a highly promising technique that affords significant advantages in mitigating the high costs and lengthy procedures associated with manufacturing precise and complex components in the aerospace industry.However,the printing process encounters uncontrollable issues,such as fluctuations in laser energy,unstable airflow,and damage to the recoater.These issues can lead to uneven powder spreading thickness,causing deposition defects that critically impact part quality.To improve the formation quality,the deposition defects caused by abnormal powder thickness must be monitored.Despite rapid advancements in online monitoring technologies,the complexity of signal data and its unclear correlation to actual part defects present significant challenges.Establishing the relationship between the deposition defect and monitoring signal for different powder thicknesses is necessary to address the issues related to powder spreading anomalies.Moreover,developing rapid and effective diagnostic methods is crucial to providing a foundation for the feedback control of defects.This study demonstrates the use of an online monitoring system that integrates proprietary photodiodes and highspeed cameras to collect and analyze data across various powder thicknesses.We establish a foundation for the online monitoring and realtime diagnostics of defects by investigating the evolution patterns of part surface quality and internal defects.Methods In the experimental study,substrates pretreated with milling are customized with designs of grooves with different depths ranging from 30μm to 300μm in 30-μm steps(Fig.4).The powder is spread across these grooves,and a recoater is used to ensure that each groove reaches the designated thickness.Singlelayer laser exposure is performed in different areas using different laser parameters(Table 1).The light intensity and melt pool area are monitored online at a frequency of 10 kHz during the printing process by using three offaxis photodiodes and a coaxial high

关 键 词：增材制造 激光粉末床熔融 在线监测 熔池光信号 沉积缺陷 

分 类 号：TH16[机械工程—机械制造及自动化] TP277[自动化与计算机技术—检测技术与自动化装置]