Meana Víctor, Cuesta Eduardo, Álvarez Braulio J, Giganto Sara, Martínez-Pellitero Susana
Department of Construction and Manufacturing Engineering, University of Oviedo, Campus de Gijón, 33203 Gijón, Spain.
Area of Manufacturing Engineering, Universidad de León, Campus de Vegazana, 24071 León, Spain.
Materials (Basel). 2022 May 24;15(11):3741. doi: 10.3390/ma15113741.
The improvement of industrial manufacturing processes requires measurement procedures and part inspection tasks to be faster and faster while remaining effective. In this sense, the capabilities of noncontact measuring systems are of great help, not only because of the great amount of data they provide but also for the ease of the integration of these systems as well as their automation, minimising the impact on the industry. This work presents a comparative study on the influence of two surface treatments performed on low-cost, high-precision metallic spheres on the suitability of these spheres to be used as artefacts for the calibration of optical sensors, specifically laser triangulation sensors. The first surface treatment is sandblasting (a mechanical process), whose effect has been studied and presented in previous work. The second treatment focused on in this paper is acid etching (a chemical process). The comparison has been performed by evaluating the same metrological characteristics on two identical groups of spheres of similar type (diameter and accuracy), each of which was subjected to a different treatment. It was necessary to obtain the reference values of the metrological parameters with high accuracy, which involved measuring the spheres with a coordinate measuring machine (CMM) by contact probing. Likewise, spheres were scanned by a laser triangulation sensor mounted on the same CMM. The results derived from both the contact and laser measurements and before and after treating the surfaces were used to compare four parameters: point density, sphere diameter, sphere form deviation, and standard deviation of the best-fit sphere to the corresponding point cloud. This research has revealed that acid etching produces better optical qualities on the surfaces than the mirror-like original ones, thus enhancing the laser sensor capturing ability. However, such chemical etching has affected the metrological characteristics of the spheres to a greater extent than that produced by sandblasting. This difference is due to the variability of the chemical etching, caused by the high aggressiveness of the acid, which makes the process very sensitive to the time of exposure to the acid and the orientations of the spheres in the bath.
工业制造工艺的改进要求测量程序和零部件检测任务在保持有效性的同时越来越快。从这个意义上讲，非接触测量系统的能力有很大帮助，这不仅是因为它们能提供大量数据，还因为这些系统易于集成及其自动化特性，从而将对行业的影响降至最低。本文对两种表面处理方法对低成本、高精度金属球的影响进行了比较研究，这两种表面处理旨在确定这些球体作为光学传感器（特别是激光三角测量传感器）校准工件的适用性。第一种表面处理是喷砂处理（一种机械工艺），其效果已在先前的工作中进行了研究和阐述。本文重点关注的第二种处理是酸蚀处理（一种化学工艺）。通过对两组相同类型（直径和精度）的球体进行相同的计量特性评估来进行比较，每组球体分别进行不同的处理。有必要高精度地获取计量参数的参考值，这涉及使用坐标测量机（CMM）通过接触式探头测量球体。同样，使用安装在同一CMM上的激光三角测量传感器对球体进行扫描。将接触式测量和激光测量在表面处理前后得到的结果用于比较四个参数：点密度、球体直径、球体形状偏差以及最佳拟合球体相对于相应点云的标准偏差。这项研究表明，酸蚀处理在表面上产生的光学质量优于镜面状的原始表面，从而增强了激光传感器的捕获能力。然而，这种化学蚀刻对球体计量特性的影响程度大于喷砂处理。这种差异是由于化学蚀刻的可变性造成的，酸的高腐蚀性导致该过程对酸的暴露时间和球体在酸液中的取向非常敏感。
