Research On Dynamic Characteristics And Fault Diagnosis Of Marine Gearbox

Under the complex working conditions,harsh working environment and variable load changes,the safety performance of the gearbox cannot be effectively guaranteed.As the core components of the gearbox,gears and rolling bearings are prone to failures,which can cause ships to fail to operate normally and even result in huge economic losses.In order to study the influence of gear failure on the gearbox,this paper establishes the dynamic model of the helical gear transmission system under the influence of traditional factors and the failure model when the gear tooth material peels off and the gear tooth wears.Numerical method is used to solve and analyze.The influence of different technical parameters on the dynamic response of gears is discussed.Finally,the empirical wavelet transform signal processing method is used to extract the features of the complex and noisy vibration response data.According to the mechanical design theory,a three-dimensional model of the helical gear is founded with reference to a 300-type marine gearbox,and the parameters of each component are set uniformly.The traditional factors such as the support stiffness of the transmission system,the meshing damping,the gear meshing stiffness,the comprehensive meshing error,and the tooth backlash and the dynamic excitation of the system are comprehensively considered.Among them,the ISO national standard method and Fourier series fitting are used to solve the gear time-varying meshing stiffness.Based on Newton’s second law,the Lagrange equations are used to establish dynamic differential equations for marine helical gear transmission systems.Aiming at the established dynamic differential equations,the Gear method with higher calculation accuracy and fast calculation speed is used to calculate the equations,and the initial displacement response of the helical gear transmission system is obtained.The vibration displacement response of the gear under different average meshing stiffness,different tooth side clearance and different comprehensive meshing error is studied,and the characteristics of the gear vibration displacement response with the change of different technical parameters are analyzed.Based on the potential energy method and the wear theory,the failure models are established respectively,and the gear vibration response with time and frequency under different failure levels are studied.The kurtosis,crest factor,root mean square and mean were used to describe various evaluation indicators for different failure levels.The degree of sensitivity.By comparing the gear’s vibration response with different failure degrees and normal working conditions,the gear’s failure vibration response characteristics are analyzed.The wavelet transform method is used to finely divide the signal frequency bands and extract features to obtain a more detailed and noise-removed vibration signal,and finally improve the signal-to-noise ratio of the signal.Through the analysis of the processed signal,it is obtained that the gear is faulty.The specific frequency components at the time can provide sample points for subsequent fault diagnosis.