Automatic Modeling Software Development Of Semi-open Integral Impeller Based On NXOpen

Turbomachinery is typically used for energy conversion,and the continuous optimization of its structure and performance promotes the development of aerospace industry,aviation industry,ship industry,petrochemical industry and others.As the core component of the turbomachinery,the structure of impeller determines the turbomachinery's performance.At present,the most domestic enterprises rely on foreign expensive professional software when designing and manufacturing impeller.The domestic research institutions lack technical reserves in the research of the impeller CAD/CAM software,and many basic algorithms need to be developed from scratch.Based on this,the NXOpen is applied to develop the automatic modeling software of semi-open integral impeller.The software can not only improve the efficiency of the impeller modeling,but also lay the foundation for rapid compilation of impeller's NC machining process under the single piece small batch processing mode,and also conforms to the current intelligent manufacturing.The main contents of the thesis are as follows:Firstly,the structure of the semi-open integral impeller is analyzed,and the process of digital model of impeller is given.Then the digital model of the impeller is established in the MATLAB software and the NX software through B-splint curve,ruled surface and other functions,which lays the foundation for the follow-up researches.In order to construct the elliptical leading edge of the impeller for improving the aerodynamic performance of the impeller,a new construction method is proposed.On the basis of the pole and polar properties of the ellipse,a method for constructing an ellipse that tangent with two intersecting straight lines at two given points is proposed,and the axial ratio of ellipse can be adjusted according to the actual requirements,and the elliptical leading edge is constructed by space transformation.Thereby,the difficult constructing problem of the elliptic leading edge due to the tangent vectors of the shroud lines(or the hub lines)on the pressure and suction surfaces at the end points are usually not coplanar is solved,and the elliptical leading edge can connect the pressure and suction surfaces of the impeller smoothly.In NX software,the method is verified by the analysis of impeller modeling.On the basis of analyzing the impeller structure and the elliptical leading edge,a semi-open impeller modeling program is built by the NX secondary development platform.Firstly,based on the original data and modeling demand,the impeller modeling menu and modeling dialog are constructed.The original data files can be read directly in the modeling dialog,and the parameters of the axial ratio of ellipse,blade' number and the radius of the blade's root are set ahead to complete the required model of the impeller,because modeling commands such as curve,ruled face,offset curve,ellipse arc,surface extension,suture entity,array and so on are completed by the kernel function,so the automatic modeling of the impeller is realized,then the efficiency of the impeller modeling is greatly improved.Finally,the surface analysis proves that the model meets actual demand.Finally,the algorithm of blade flank milling is studied.The double points offset(DPO)method most widely used in engineering is analyzed.Through the differential geometry knowledge,the calculation process of the cylindrical milling cutting axis vector,the position of the cutter center and the geometric error is given,and the error distribution law is analyzed by an actual example.The processing simulation is realized in the NX software.