| The overall impeller was widely used in aviation,energy,ship and other industries,and its processing quality can directly affect the efficiency and performance of turbine machinery.The integral impeller has the characteristics of large distortion and narrow flow channel.It belongs to the typical difficult to be machined parts,especially for the titanium alloy integral impeller,which is a complex part which combines the characteristics of the titanium alloy material and the difficult machined structure of the integral impeller.The efficient machining of titanium alloy integral impeller has always been the focus of scholars and engineers.Therefore,in this dissertation,the high efficiency machining of the titanium alloy integral impeller is studied,based on the characteristics of multi-axis milling of titanium alloy,from the path planning of the cutter and the optimization of milling parameters.The main contents and conclusions are as follows:(1)An accurate mathematical model of impeller was established in UG software by using the cubic non-uniform rational B-spline principle.A titanium alloy monolithic impeller processing scheme was tentatively formulated in conjunction with relevant processing manuals,according to the geometry and material properties of the impeller.(2)Multi-axis milling titanium alloy was studied using orthogonal experiment method processing features: analyzed the multi-axis milling parameters of the milling force and surface roughness of the influence degree and trend.The regression prediction model of milling force and surface roughness of TC4 titanium alloy with cemented carbide ball cutter was established under the condition of emulsion as milling fluid,and the significance of the regression model was analyzed.(3)Computation of tool axis vector and tool rail visualization using MATLAB and MAX-PAC,UG Co-simulation.The cutting path of integral impeller machining is planned by combining the isometric method of outer edge surface and the method of spiral cutter.In order to avoid the interference and collision of the tool in the machining process,the tool shaft declination angle range was determined,and the continuous optimal tool path trajectory was fitted using the linear interpolation method.Finally,the feasibility and superiority of the trajectory are verified by simulation and practical experiments.(4)Improved MATLAB multi-objective function gamultiobj based on NSGA-II,providing the basis for solving multi-objective functions.Aiming at the high cost and low efficiency of titanium alloy integral impeller rough machining,a multi-objective optimization mathematical model was established with the objective function of minimizing tool consumption and milling efficiency.In order to meet the requirements of high surface quality and high efficiency in the finish machining of titanium alloy integral impeller,a multi-objective optimization mathematical model with the optimal surface quality and the highest milling efficiency as objective function was established.By the improved algorithm toolbox more than 2 objective optimization problem of Pareto optimal solutions.By combining the theoretical analysis with the actual processing test,the superiority of any set of parameters in the Pareto solution concentration is verified.Compared with the parameters of the experienced milling,the optimized milling parameters are used to process the processing,which greatly improves the processing efficiency,reduces the processing cost and improves the quality of the processing surface.The research work provides technical support for the processing of complex structure difficult to machine material parts,and the research results have good engineering application value. |
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