| Gear transmission system is an important power and motion transmission device in modern industry.It has high transmission efficiency and constant power,so it is widely used in various mechanical equipment,such as aviation and navigation,electric equipment,transportation machinery,cutting machine tools,and machining,mineral smelting and petrochemical industries have been widely used.The vibration characteristics of gears directly affect the accuracy and transmission efficiency of the transmission system.Poor vibrations can cause high and low frequency noise and affect the working environment.With the development of various types of machinery that use gear transmission systems in the direction of high-speed reliability and high-precision mute,there is an increasing demand for the precision of gear systems.Therefore,the research on the vibration and noise characteristics of the gear system becomes more and more important.Based on gear dynamics and structural acoustics,this paper takes the spur gearbox as the research object,establishing a dynamic equation of the gear-rotor-bearing system by using the Lagrangian equation to study the steady-state response characteristics of the system.The finite element method is used to analyze the vibration response of the housing.The acoustic boundary element model of spur gearbox is established to analyze the vibration and noise characteristics of the gearbox.By establishing a spur gear transmission system test device,the accuracy of the theoretical simulation in this paper is verified.The main content of this article is summarized as follows:(1)A dynamic analysis model of a spur gear-rotor-bearing coupling system is established to study the nonlinear vibration characteristics of the system.In the establishment of the system model,the changes of the gear backlash,the periodic variation of the friction force,as well as the changes of the meshing stiffness and meshing damping is considered.A 16-DOF bending-torsion coupled dynamics model of the gear-rotor-bearing system is established by using Lagrange equation.The dynamic differential equations are solved by Newmark-β algorithm.The influence of parameters such as initial gear backlash and rotation speed on the vibration characteristics of the coupled system is studied.(2)A housing model is established to analyze the steady-state response and sound radiation of the housing when it is subjected to harmonic excitation.Vibrations,generated during gear meshing process,are transmitted to the bearing through the shaft.Then vibrations are transmitted to the housing,causing the vibration of housing.The bearing forces are calculated by using the gear-rotor-bearing dynamic model,which is taken as the excitation for the gearbox.Then,a housing finite element model is constructed,and the housing surface velocities excited by the bearing forces are obtained.The acoustic boundary element model of the housing is established,and the acoustic radiation characteristics of the housing are calculated by using the vibration velocity of the housing surface unit obtained above.(3)The accuracy of the simulation results of dynamics and acoustics is verified by an experimental spur gearbox.According to the same size of the theoretical simulation model,a vibration and noise experimental stand for a spur gearbox is set up,and the experimental research is carried out from the aspects of dynamics and acoustics.The vibration displacement data of the input and output shafts are collected,and the data are compared with the simulation results.Acoustic signal acquisition equipment is used to measure the sound pressure signal around the gearbox.After comparing the experimental data with the simulated sound pressure level,it is found that the results are very similar.The sound pressure level curves at the meshing frequency of the gear pair and their multiples show different peaks.Excluding the effects of machining errors,assembly errors and background noise,the experimental results verify the accuracy of the theoretical simulation. |
