The Three-dimensional Measurement Research And Application Of Aero-engine Blade

The engine is the core of the aircraft,while the blade is the key part of the aircraft engine.The geometrical shape of the blade will have an important impact on the safety of flight,so accurate three-dimensional measurement of the blade must be carried out.The 3-d measurement of blades should meet the requirements of high accuracy,high efficiency and low cost at the same time.On the basis of a comprehensive comparison of various current three-dimensional measurement methods,this paper selects the three-dimensional measurement technology of structural light as the main method of blade measurement,and conducts relevant research.The main research work is as follows:1.Compared the characteristics of current 3d measurement technology comprehendsively,and analyzed the principle and implementation method of 3d measurement technology of surface structure light in depth.Through comparison of the coding,the combination coding method that can solve the phase effect is better and improve the resolution and accuracy at the same time is finally selected.The truncation phase of the blade is obtained by four-step phase shift.The decoding period of the blade is obtained by gray coding.The absolute phase of the blade is obtained by the phase unwrapping.The projection Angle of blade is calculated according to the relation between absolute phase and projection Angle.The triangular method is used to calculate the blade height.2.In this paper,the binarization of gray coded pattern in blade dephasing is studied.By analyzing the binarization algorithm,a binarization algorithm combining global threshold method and local threshold method is designed,which takes into account the accuracy and efficiency of image binarization.During the calculation of the absolute phase,the dislocation of the decoding periodic boundary is corrected to obtain the accurate absolute phase of the blade.3.The 3-d measurement system of aero-engine blade was constructed by using the principle of surface structure light,and the internal and external parameters of the system were calibrated.In the blade measurement experiment,gray coding patterns and phase shift patterns were compiled,and these patterns were projected onto the blade in turn.Then,image acquisition and phase resolution were carried out to obtain three-dimensional measurement point cloud data of the blade.4.Improved the ICP algorithm and applied it to the splicing process of blade point cloud data to generate a three-dimensional model of the blade with higher accuracy.The error analysis of blade profile is realized by comparing the 3-d measurement model with the CAD reference model.