Research On Three-dimensional Topography Measurement Technology Of Aero Engine Blade Based On Line Structure Light

The blade was an important component within the aero engine,to ensure the safe of the aero engine during operation,it was necessary to ensure that the blade had high quality,high performance and high life。In recent years,due to engine blade breakage caused by aviation flight accidents had occurred frequently,blade rupture was also known as the "first killer" of an aero engine accident。the blade was a class of parts with a typical free surface,and its own quality,performance and service life were entirely determined by its surface shape。therefore,it was very important to study the surface three-dimensional topography。at present,in the field of aero engine blade surface three-dimensional measurement,domestic and foreign scholars had done a lot of experimental research,put forward many solutions,and for different types of blade measurement had its unique advantages,but the current aviation industry in the field of high precision,high efficiency,automation,low price and other requirements,these measures were difficult to achieve at the same time。Therefore,it has being the current research hotspot to explore a series of three-dimensional measurement method of aero engine blade which can realize automation,low cost,high precision and high efficiency。In this paper,the three-dimensional shape measurement of aero engine blade surface is presented,a three-dimensional scanning measurement method based on line structured light is proposed and studied in depth 。 Firstly,The principle of three-dimensional measurement technology of line structured light is analyzed,and a three-dimensional model of line structured light is established,a three-dimensional optical system is designed based on the model。Secondly,The system calibration technology is studied deeply,and the internal and external parameters of the camera are calibrated by Zhang’s two-dimensional camera calibration method。the structural parameters of the line structured light sensor are calibrated by the cross-ratio invariant method based on the free-moving two-dimensional target。Thirdly,A polynomial fitting method for reducing the high light reflection of aero engine blade is studied,and various interference factors affecting the image quality of laser fringe are analyzed in detail,and a solution is put forward。Fourthly,An improved hessianmatrix laser stripe center extraction method based on geometric center method and gaussian decomposition method is proposed,geometric center method is used to extract the left and right boundary positions of each line of laser fringe image,the two-dimensional gaussian convolution operation in the original hessian matrix is decomposed into two multiplied one-dimensional gaussian convolution operations,and the new hessian matrix is constructed to extract the laser stripe center accurately。Fifthly,The three-dimensional topography measurement of the surface of the aero engine blade is carried out by using the line structured three-dimensional scanning measurement system designed in this paper。The experimental results and errors are analyzed。on this basis,a mechanical structure of a three-dimensional detection instrument for aero engine blade model。In this paper,the method of measuring the three-dimensional topography of the surface of the aero engine is proposed by using the three-dimensional technique of linear structured light,the experimental results show that the method can effectively measure the surface three-dimensional morphology of the aero engine blade。the improved hessian matrix laser stripe center extraction method proposed in this paper can realize the low cost and high efficiency three-dimensional measurement of the aero engine blade,and combine the mechanical model of the three-dimensional detection instrument of the paper to realize the automation and high precision measurement of the aero engine blade provides a theoretical basis.