| Aero-engine is the "heart" of an aircraft,and its performance directly determines the state level of the aircraft,while the quality of aero-engine blade plays a crucial role in improving the performance of the engine.Blade working environment emerged as the main characteristic of high temperature and high pressure,large load,in the event of failure will lead to serious flight safety accident,thus affecting the quality of blade shape dimension precision detection is particularly important,because the blade has type surface complex,thin,twisted,manufacturing high accuracy requirement and feature sizes and large number,the aircraft engine manufacture and testing about 30%of the workload from the blade.With the rapid development of modern measurement technology,various detection technologies of aero-engine blade come into being,which provides a reliable technical basis for improving the precision and efficiency of blade measurement.It is a new research direction to realize automatic measurement of key parameters of aero-engine blade.Based on the investigation of the current situation of manufacturing technology and measuring technology of aero-engine blade,this paper puts forward the innovation and improvement of the measuring mode of engine blade,replaces the analog measurement with the digital measurement,and uses the optical non-contact measurement method to achieve the high-precision and high-efficiency measurement of key parameters of engine blade profile.The main work of this paper is as follows:(1)High dynamic image acquisition and system parameter self-calibration technology in 3d measurement of blade profile are studied to solve the problem that the actual industrial application environment affects the final measurement accuracy of blade profile.Aiming at the high dynamic image acquisition,an exposure parameter optimization algorithm based on the high dynamic raster image acquisition method guided by the multi-reflection imaging law is proposed,which can quickly calibrate the optimal exposure parameters according to the current measurement scene and ensure the quality of image acquisition.Aiming at the self-calibration technology of system parameters,a real-time optimization method of system parameters adjustment with coupling focal length proportional constraint is proposed,which can directly calibrate the optical geometric parameters and 3d measurement parameters with the measured grating images,and obtain the in-situ geometric description of the optical elements and the accurate 3d coordinates of the corresponding points.These two methods overcome the impact of reflective and vibration environment on the accuracy of point cloud data.(2)Some algorithms such as point cloud de-noising,point cloud simplification and point cloud triangulation are applied to realize the efficient processing of 3d data of blade.The noise in the point cloud model is processed by the point cloud de-noising algorithm based on statistics.The method of point cloud simplification based on curvature is adopted to simplify point cloud data to reduce the computing cost of data processing.Using a point cloud triangulation algorithm based on greedy projection,the topological relation of discrete data point set is established effectively,and the original image is reconstructed accurately.(3)The overall design scheme of automatic three-dimensional measurement system for blade profile is proposed,the system is constructed,and the accuracy of the system is tested and evaluated.The measurement accuracy of single Angle is better than0.029 mm,and the measurement accuracy of multi-angle splicing is 0.060 mm.The overall three-dimensional measurement of the actual blade profile was carried out by the designed system,and the overall three-dimensional model of the blade was compared with the CAD model,which showed good consistency and verified the effectiveness of the proposed method and design scheme. |
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