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Prediction of powder bed thickness by spatter detection from coaxial optical images in selective laser melting of 316L stainless steel
Zhang, Weihao1,2; Ma, Honglin1,3; Zhang, Qi1,3; Fan, Shuqian1,3
2022
摘要The uniformity of a recoated powder layer affects the performance of parts manufactured by SLM directly, while it is related to the characteristics of spatters. The small spatter moves pretty fast, while the low optical transmittance in the spectrum of a hot spatter in the coaxial optical path of SLM equipment prevents clear imaging of this target with high contrast. In this study, a coaxial optical path with an enhanced optical transmittance is used for imaging the melt pool and its surrounding phenomena simultaneously. An experimental system was developed using a high-speed camera for coaxial observation of hot spatters in the SLM process. The problems of limited field of view and high measurement uncertainty of an off-axis process monitoring system are solved. For defocused and distorted spatter images, both a segmentation algorithm and an object detection method have been proposed and proved to be effective. It was found that the direction and strength of the local airflow field could be estimated via the curvature of the spatter trajectory. More importantly, the quantity of spatters detected is positively related to the amount of powder locally distributed on the baseplate, which is useful to estimate the powder bed thickness at this position. (c) 2021 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
关键词Additive manufacturing Selective laser melting Spatter Coaxial monitoring High-speed imaging Machine vision
DOI10.1016/j.matdes.2021.110301
发表期刊MATERIALS & DESIGN
ISSN0264-1275
卷号213页码:12
通讯作者Zhang, Qi(zhangqi@cigit.ac.cn) ; Fan, Shuqian(fansq@cigit.ac.cn)
收录类别SCI
WOS记录号WOS:000734388700003
语种英语