Influence of the Inert Gas Flow on the Laser Powder Bed Fusion (LPBF) Process
Influence of the Inert Gas Flow on the Laser Powder Bed Fusion (LPBF) Process
复制标题
惰性气体流对激光粉末床熔融 (LPBF) 过程的影响
DOI：
10.1007/978-3-030-54334-1_14
复制
发表时间：
2020
影响因子：
11
通讯作者：
M. Cloots
中科院分区：
文献类型：
--
作者：
F. Wirth;Alex Frauchiger;Kai Gutknecht;M. Cloots
已知惰性气体流在整个构建平台的工艺稳定性和一致的工艺结果方面对激光粉末床熔合（LPBF）工艺具有显著影响。因此，惰性气体流的优化导致如下的部件质量的直接和间接改进。如果气流能够稳定而有效地去除熔化过程中出现的烟灰颗粒，则可以避免激光束或激光窗口上的碎片的散射和衰减，这将间接损害所构建部件的质量。溅射颗粒也应该被去除，因为它们会直接导致生产部件内部的粘合缺陷。为此，本文基于计算流体力学（CFD）、颗粒跟踪和实验研究，对自行研制的LPBF机内的气流进行了系统的优化。本文详细介绍了工艺气体流量和气体类型对飞溅和烟灰颗粒的影响。根据模拟结果，在极端工艺参数下，碳烟去除的潜在恶化的代价下，通过较小的保护气体入口高度来改善碳烟去除。模拟结果已被验证的气体流速和建成的零件的密度的测量。不同的工艺气体类型的优点和缺点，并得出气流设计的建议。
The inert gas flow is known to have a significant impact on the laser powder bed fusion (LPBF) process in terms of process stability and consistent process results across the whole build platform. Thus, the optimization of the inert gas flow leads to both direct and indirect improvements of the part quality as follows. If the gas flow can steadily and efficiently remove soot particles emerging from the melting process, scattering and attenuation of the laser beam or debris on the laser windows can be avoided, which would indirectly impair the quality of the built parts. Spatter particles should be removed as well because they can directly lead to bonding defects inside the produced parts. Therefore, the gas flow in a self-constructed LPBF machine has been optimized systematically based on computational fluid dynamics (CFD), particle tracking and experimental studies. Herein the effect of the process gas flow and gas type on spatter and soot particles is presented in detail. According to the simulation results, the soot removal is improved by a smaller shielding gas inlet height at the cost of a potential deterioration of the soot removal at extreme process parameters. The simulation results have been validated by measurements of the gas flow velocity and of the density of the built parts. The advantages and disadvantages of different process gas types are shown and recommendations for the gas flow design are derived.