Automatic Positioning for Optical Scanning of Overlapping Fan-Blades

This research applies ATOS, an optical scanning device, to scan fan blades which possess overlapped geometry between blades. The surfaces to be investigated include a pressure surface, a suction surface and two hub surfaces adjacent to the pressure and suction surfaces respectively. Through numerous scanning practices, rules are found to position the fan blades in proper orientations so that data points of the four types of fan-blade surfaces can be completely obtained. The scanning sequence include: (1) rotate the fan with respect to the z-axis so that the fan can be set parallel to the straight-line connecting the two cameras of ATOS, (2) rotate the fan with respect to the x-axis so that the whole pressure surface can be located inside the scanning region of cameras, (3) rotate the fan w.r.t. the z-axis to let the suction surface be completely scanned, (4) rotate the fan w.r.t. the y-axis so that the hub surface can be located inside the camera scanning region, and (5) rotate the fan w.r.t. the z-axis so that the other hub surface can be scanned. To verify the proposed scanning sequence, this research uses Pro/Toolkit and Visual C++ to develop the programming codes so that the positioning angles for the four different types of surfaces can be automatically found from the Pro/ENGINEER part model of a fan. The goal of automatic positioning for scanning of fan blades can thus be achieved. It is concluded that the research results contribute the possibility of scanning overlapped fan blades in an automation manner, and also in little time-span.