Abstract When looking for any metrological verification of parts manufactured by metal laser printing with optical equipment, it is necessary to ensure the traceability of the measurements that can be obtained. The difficulty of this process lies in the fact that these measurements are obtained on point clouds captured from surfaces with high form errors and poor surface finishes, even when this type of surface usually undergoes processes to improve the surface finish, such as sandblasting. This research focuses precisely on the analysis of the metrological suitability of a laser line scanner (laser triangulation sensor) on parts manufactured by Selective Laser Melting (SLM). The study starts from the design of a test part specifically oriented to the printing process with SLM metal powder bed. This test part was printed in 17-4PH stainless steel and then sandblasted. The test part was measured in a Coordinate Measuring Machine (CMM), obtaining reference GD&T values. The measurement was carried out under pre-sandblasting ("as built") and post-sandblasting conditions, thus providing interesting information about the erosion rate of this post process. A state-of-the-art laser sensor was employed for the metrological comparison, mounted on the same available CMM that was used for contact measurements. In this research three analyses were carried out: the quality of 3D metal printed parts with respect to CAD model, the effect of the sandblasting post-process, and the accuracy of the measurements obtained with the laser line sensor. In addition, this work conducts an in-depth study about the influence of point cloud treatment and filtering procedures, by comparing the filtering methods applied by different reverse engineering software packages. The study leads to the conclusion that filters based on the standard deviation of the point cloud are the best candidates in order to obtain laser measurements closer to the contact measurements.

中文翻译：

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用于测量选择性激光熔化部件的激光线扫描仪能力

摘要 在寻找使用光学设备对金属激光打印制造的零件进行任何计量验证时，必须确保可以获得的测量结果的可追溯性。这个过程的难点在于，这些测量是在从具有高形状误差和表面光洁度差的表面捕获的点云上获得的，即使这种类型的表面通常经过处理以改善表面光洁度，例如喷砂。这项研究的重点是分析激光线扫描仪（激光三角测量传感器）对选择性激光熔化 (SLM) 制造的零件的计量适用性。该研究从设计专门针对 SLM 金属粉末床打印过程的测试部件开始。该测试部件采用 17-4PH 不锈钢印刷，然后进行喷砂处理。在坐标测量机 (CMM) 中测量测试部件，获得参考 GD&T 值。测量是在喷砂前（“建成”）和喷砂后条件下进行的，因此提供了有关此后处理侵蚀率的有趣信息。最先进的激光传感器用于计量比较，安装在用于接触测量的相同可用 CMM 上。在这项研究中，进行了三项分析：3D 金属打印部件相对于 CAD 模型的质量、喷砂后处理的效果以及使用激光线传感器获得的测量精度。此外，这项工作通过比较不同逆向工程软件包应用的过滤方法，对点云处理和过滤程序的影响进行了深入研究。该研究得出的结论是，基于点云标准偏差的滤波器是获得更接近接触测量的激光测量的最佳候选者。