Research On The Press-fit Force Detection And The Key Technology Of The Assembling Of Wheel And Axle

In the process of locomotive wheel-set assembly,the accuracy of force detection is a key factor affecting press-fit quality.At present,the force of wheel-set assembly equipment is detected mainly through the pressure sensor in tail of the hydraulic cylinder.It's an indirect measurement method and the accuracy of this method can be affected by the hydrodynamic factors,friction and cylinder deformation.In this paper,the effects of the accuracy of the wheel-set press-fit force were analyzed through theoretical derivation and simulation analysis etc.And the exactitude of the study was verified by experiments.The theory studied in this paper was applied to practice and developed a precise,high reliability and low cost system for measuring the wheel-set press-fit force.The main contents of this paper are as follows:(1)The pressure difference between the tail of the cylinder and the piston was deduced according to the N-S equation.The laminar flow state of the liquid in the cylinder was analyzed by MATLAB.And the effect of internal turbulent flow of hydraulic cylinder on force detection was studied by using dynamic mesh method and k-? model of FLUENT.With the above analysis,the effects of the piston speed,the oil viscosity,the piston rod length on force detection were analyzed.(2)Based on the modified LuGre model,the friction model was built by using Simulink.The method of parameters identification of modified LuGre model was proposed by analyzing the meaning of each physical parameter,and the effects of the friction on the accuracy of the press-fit force were studied by simulation.(3)According to the characteristics of H-W model,the deficiencies of the model in describing the deformation of hydraulic cylinder are presented.The H-W model was improved based on elastic deformation theory.The improved H-W model was built by using Simulink,and the effects of the cylinder deformation on the accuracy of the press-fit force were studied by simulation.(4)The physical parameters in the simulation model was obtained by experiment though building the experimental platform.The LuGre model which reflects the characteristics of the cylinder friction and the H-W model which reflects the deformation characteristics of the cylinder were verified by the experimental data.(5)This paper proposed the methods that can be used to improve the accuracy of press-fit force in the practice according to the characteristics of the impacts of the fluid dynamics,the friction and the deformation of the cylinder.The press-fit force was corrected by correcting program which was applied in practice.The correcting program was proved to be effective by experiment.