Research On Boundary Extraction And 3D Reconstruction Of Aeroengine Blade Point Cloud Data

In the wake of developments in science and technology,the number of Chinese aircraft is increasing recent years.Aero engine,as the key component of the aircraft,has the highest importance and the market value in maintenance.As an important part of aero engine,blade has many characteristics,such as wide varieties,large quantity,complex size and specification,difficult to repair and so on.In the field of technology,A variety of blade repair welding equipment has been developed abroad,but it is relatively backward in the field of high precision reconstructing and welding repair in China.In order to break the technical blockade of foreign countries to China,reduce economic losses and achieve domestic restoration of aircraft blades,it is urgent to develop a set of blade extension,reconstruction and welding repair methods independently.For blade repair,3D measurement,3D reconstruction and welding repair are required.Among them,the high accuracy 3D reconstruction of the point cloud data is utterly important after obtaining the point cloud data of the aero engine blade.For aero blades which take service in a bad environment for long time,it is easy to have defects such as edge angle defect and so on,so the repair of aero blade is necessary.In the process of blade repair,the original point cloud was firstly obtained by 3D measurement,then point cloud model is obtained by preprocessing and splicing of the original point cloud.Next,boundary of the point cloud model is extracted and fitted,then the blade is fitted by the spline theory,and the blade model that still lacks angle is obtained.Finally,the complete blade is obtained by extending.When the boundary extraction is extracted,there is a problem of discontinuous boundary and low efficiency for extracting the boundary of point cloud based on the curvature maximum method,a point cloud boundary extraction method for aero engine blades based on the Otsu threshold method is proposed.When the spline is fitted,it is considered that the blade of an aero engine is the characteristic of the free surface of the space,an aero engine blade fitting method based on B-Spline theory is proposed,finally,the feature of the blade surface is considered,and the part of the blade is extended and repaired according to the similarity of the blade.Taking the sixth stage blade of an aero engine compressor as an example,this paper uses the proposed method to carry out boundary point cloud extraction and 3D reconstruction.In the simulation and experiment,several points were selected to compare with the corresponding points in the model,and it is found that the error decreased significantly,and the error of the extension terminal was also within the error range.As a result,the proposed method can extract boundary point cloud data accurately,and the reconstructed model has high accuracy.Consequently,this method can be applied to the extension and reconstruction of aero engine defective blades.