Research On Structural Optimization Design Of CNC Gantry Milling Machine For High Speed Railway Turnout

In recent years,high-speed railway industry has developed rapidly.As an important part of railway track,the processing and manufacturing of high-speed railway turnout has attracted more and more attention.High-speed railway turnout was usually made of high manganese steel materials,it was a typical difficult to machining materials,and because the turnout processing generally adopts molding milling cutter processing molding,it was a heavy cutting type,which puts forward very high requirements for processing equipment.In order to meet the processing needs of high-speed railway turnout,the machine tool was required to have high enough static and dynamic stiffness and good structural stability of the machine tool,in addition,the vibration resistance of the machine tool was also put forward higher requirements.In this paper,high-speed railway turnout CNC gantry milling machine as the research object,the use of finite element analysis technology in the design stage of the machine tool to do a comprehensive analysis of its static and dynamic characteristics,and the use of modern optimization algorithm and finite element analysis software on the key parts of the machine tool and the structure of the overall machine size optimization.In this paper,the three-dimensional mathematical model of CNC gantry milling machine for high speed railway turnout was constructed,the finite element model was established,the linear static analysis and modal analysis were carried out to verify the rigidity and strength of parts and components of the milling machine.The analysis results show that the maximum deformation of the column and the beam can not meet the design index,which needs to be further optimized.According to the results of harmonic response analysis,the structure of the machine should be optimized to improve the natural frequency of the machine.The dimension optimization of single working condition and single target for column and beam was carried out respectively,and the maximum deformation of column,beam and milling machine after optimization meets the design index.Aiming at the problem of low base frequency of milling machine,the key dimension affecting the base frequency of the milling machine was found out through sensitivity analysis,and the single working condition and single target dimension were optimized.Two multi-objective optimization schemes based on eclectic programming andadaptive response surface method were proposed.Through comparative analysis,the second scheme was selected as the design scheme of this study.The optimized first order natural frequency was 34.62 hz,which was 17.1% higher than that before optimization.The optimized second-order natural frequency was 39.54 hz,which was 19.0% higher than that before optimization.After optimization,the maximum deformation of the whole machine was 0.047 mm,which was 29.9% lower than that before optimization.The optimized quality was 34.58 t,which was 8.7% lower than that before optimization,Meet the design requirements.Through static stiffness test,stress test and precision test,the accuracy of finite element analysis was verified,and the feasibility of multi-objective optimization was also proved.