Lee ChaBum, Mahajan Satish M, Zhao Rui, Jeon Seongkyul
Department of Mechanical Engineering, Tennessee Technological University, 1 William L. Jones Dr., Cookeville, Tennessee 38505, USA.
Department of Electrical and Computing Engineering, Tennessee Technological University, 1 William L. Jones Dr., Cookeville, Tennessee 38505, USA.
Rev Sci Instrum. 2016 Jul;87(7):075113. doi: 10.1063/1.4958882.
This paper presents a new dimensional metrological sensing principle for a curved surface based on curved edge diffraction. Spindle error measurement technology utilizes a cylindrical or spherical target artifact attached to the spindle with non-contact sensors, typically a capacitive sensor (CS) or an eddy current sensor, pointed at the artifact. However, these sensors are designed for flat surface measurement. Therefore, measuring a target with a curved surface causes error. This is due to electric fields behaving differently between a flat and curved surface than between two flat surfaces. In this study, a laser is positioned incident to the cylindrical surface of the spindle, and a photodetector collects the total field produced by the diffraction around the target surface. The proposed sensor was compared with a CS within a range of 500 μm. The discrepancy between the proposed sensor and CS was 0.017% of the full range. Its sensing performance showed a resolution of 14 nm and a drift of less than 10 nm for 7 min of operation. This sensor was also used to measure dynamic characteristics of the spindle system (natural frequency 181.8 Hz, damping ratio 0.042) and spindle runout (22.0 μm at 2000 rpm). The combined standard uncertainty was estimated as 85.9 nm under current experiment conditions. It is anticipated that this measurement technique allows for in situ health monitoring of a precision spindle system in an accurate, convenient, and low cost manner.
本文提出了一种基于曲边衍射的新型曲面尺寸计量传感原理。主轴误差测量技术利用附着在主轴上的圆柱形或球形标准工件，通过非接触式传感器（通常是电容式传感器（CS）或涡流传感器）指向该标准工件。然而，这些传感器是为平面测量设计的。因此，测量具有曲面的目标会产生误差。这是因为平面和曲面之间的电场行为与两个平面之间的电场行为不同。在本研究中，将激光入射到主轴的圆柱表面，光电探测器收集目标表面周围衍射产生的总场。在所提出的传感器与CS在500μm范围内进行了比较。所提出的传感器与CS之间的差异为全量程的0.017%。其传感性能显示分辨率为14nm，在运行7分钟时漂移小于10nm。该传感器还用于测量主轴系统的动态特性（固有频率181.8Hz，阻尼比0.042）和主轴跳动（2000rpm时为22.0μm）。在当前实验条件下，合成标准不确定度估计为85.9nm。预计这种测量技术能够以准确、方便和低成本的方式对精密主轴系统进行原位健康监测。
