Machining Analysis And Cutting Parameters Optimization Of Steam Turbine Blades

The thin-walled blade is the core component of the steam turbine.Due to its weak rigidity,it is deformed by the milling force during the machining process,which affects the machining accuracy and quality of the blade processing,and is not conducive to the production of the enterprise.Therefore,this paper takes thin-walled blades as the research object,carries out a series of research,such as the determination of the relative position of cutter and workpiece,the establishment of milling force model of ball-end milling cutter,the deformation analysis of blade processing,multi-objective optimization of cutting parameters,panoramic simulation processing and experimental verification.Specific research contents and results are as follows:1.Determine the relative position of tool and workpiece.This paper analyses the method of creating the blade channel profile,and carries out the three-dimensional modeling of the blade.According to the actual processing technology of the blade,the tool path is compiled by UG/CAM,and the CLSF tool position file is generated.Through theoretical analysis,the contact point coordinates between the tool and the workpiece and the normal vector direction of the surface at the contact point are solved,and its correctness is verified,thus the relative position between the tool and the workpiece is determined.It lays a foundation for the position of applied force in the subsequent research of blade deformation.2.Establish milling force model of ball end milling cutter.The orthogonal experiment design method is used to design the cutting parameters combination of the milling force simulation experiment;the AdvantEdge software is used to simulate the milling force,and the milling force magnitude in three directions corresponding to each group of parameters is obtained;the regression equation coefficients are solved by Matlab software,so that the milling force prediction model is established and its validity is verified,which can be used for the subsequent research on the machining deformation of blades.The magnitude of the applied force provides a theoretical basis.3.Deformation analysis of blade processing.Based on ANSYS Workbench,the finite element model of blade deformation analysis is established,and the machining contact point between tool and workpiece corresponding to NC program is created,and the local coordinate system is established at the contact point to study the deformation of blade at each contact point.The influence of four cutting parameters on the deformation of blade is studied and the rule is obtained:the deformation of blade increases with the increase of cutting width.Slowly increases,increases with the increase of feed,decreases with the increase of cutting speed and tends to remain unchanged,increases with the increase of cutting depth and has a greater impact;after adjusting parameters,finite element simulation is carried out to verify the correctness of the law,which provides a theoretical reference for subsequent optimization of cutting parameters.4.Multi-objective optimization of cutting parameters.The optimal Latin hypercube design test method was used to determine 30 sets of sample points of four initial design variables,cutting width a_e,cutting speed v_c,feed f_z and cutting depth a_p;the approximate model of response surface of each design variable was established,and the accuracy of response surface model was tested and error analysis was carried out to show that the test was qualified;the interactive influence of design variables on the approximate model of response surface was analyzed.The deformation De and processing time T are taken as the objective of parameter optimization,and the AMGA adaptive mutation genetic algorithm is used to optimize the four cutting parameters to obtain the optimal solution.The optimized parameters can reduce the deformation and shorten the processing time,thus achieving the goal of optimization.5.Panoramic simulation processing and experimental verification.The NC program file of NC machining is compiled with optimized cutting parameters,and the NC program is checked by Vericut panoramic simulation processing software.After verifying the program is correct,the blade is processed by HAAS four-axis NC machine tool in the United States,and the airway surface of the finished blade is tested by Haxconn coordinate measuring instrument.The actual processing test results and simulation values are carried out.The results prove the reliability of the finite element method to simulate the deformation of blade processing,and also prove the feasibility of the optimization scheme of cutting parameters,which is of great significance to the efficient production of enterprises.