Study on five-axis vision measuring method of spatial coordinates of film cooling holes

To inspect the spatial coordinates of film cooling holes using the five-axis vision measuring system set up in the paper, methods of coordinate systems establishment and measuring data conversion were studied, which could be used to translate the measuring data of hole center from the image space to the blade space.In the application, mathematical model containing multiple coordinate systems were established, as well as the translating relationship among them.In this way, the 2D image data of the measured hole center could be converted to 3D physical data, and then transformed into the design coordinate system of blade.To verify the feasibility and function of the method proposed, the target hole on the leading edge of a turbine blade was measured 10 times by the system, in which the repeatability accuracy of x, y and z of the hole center were all smaller than ±15 μm respectively.Also, a row of film cooling holes on the blade were inspected to derive their spatial parameters.As the experimental results showed, the five-axis measuring method put forward could be utilized to fulfill the inspecting assignment of the distributions of film cooling holes, which could serve as a foundation for the subsequent comparison with the design data and quality evaluation.