Taking helical gear as the research object, through the analysis and research of static transmission error, friction excitation and helical gear meshing stiffness after modification, the dynamic model of helical gear system coupled with 8-DOF modification and time-varying friction excitation is established, and the dynamic response of helical gear system is obtained by Runge Kutta method, The effects of modification and friction coefficient on the dynamic response characteristics of helical gear system are analyzed. Based on the dynamic meshing force obtained from the coupling dynamic response analysis of helical gear modification and friction excitation, an acoustic boundary element model is established to simulate and analyze the influence of modification and friction on the vibration and noise of helical gear system. The main conclusions are as follows:
① Romax software is used to determine the optimal modification amount of helical gear tooth profile linear modification, tooth profile parabola modification and tooth direction modification drum, calculate the static transmission error of helical gear system after modification by each modification method, and obtain the static transmission error with the minimum peak to peak value of helical gear system.
② Assuming that the load is evenly distributed along the length of the contact line, based on the calculation method of time-varying contact line, time-varying friction and time-varying friction considering time-varying meshing force, the time-varying contact line, time-varying friction and friction torque of helical gear are calculated, and the effects of different helix angle and different contact tooth width on the time-varying contact line The influence law of time-varying friction and time-varying friction torque. With the increase of helix angle, the variation range of contact line length amplitude of helical gear increases; The overall amplitude and variation range of helical gear contact line length increase with the increase of contact tooth width.
The friction force and friction torque of single pair of helical gears decrease with the increase of helix angle and contact tooth width; The overall amplitude of friction torque of total meshing teeth increases with the increase of helix angle and contact tooth width. Based on the calculation method of helical gear meshing stiffness per unit contact line length of tooth profile end face, the meshing stiffness before and after helical gear modification is calculated.
③ Considering the influence of helical gear modification on stiffness excitation and friction excitation, the coupling dynamic model of helical gear system modification and friction excitation is established. The dynamic response results of helical gear are solved and calculated by Runge Kutta method. The effects of friction and non friction excitation, different friction coefficients before and after modification and after modification on the dynamic response characteristics of helical gear system are obtained. Friction excitation will cause periodic vibration perpendicular to the meshing line direction, and increase the vibration amplitude and dynamic meshing force in the meshing line direction. The vibration amplitude of friction force and the fluctuation range of dynamic meshing decrease after modification, and the vibration amplitude perpendicular to the direction of meshing line and meshing line decreases after modification. With the increase of friction coefficient, the vibration amplitude of helical gear system in all directions increases, and the vibration amplitude of friction and the fluctuation range of dynamic meshing also increase.
④ The acoustic boundary element model is established. Based on the dynamic meshing force obtained from the coupling dynamic response analysis of helical gear modification and friction excitation, the vibration and noise of helical gear system are simulated and analyzed, and the effects of different friction coefficients before, after and after helical gear modification on the vibration and noise of helical gear system are obtained. After modification, the sound pressure at each frequency of the helical gear system decreases, about 1 ~ 3dB. For different friction coefficients, the vibration and noise amplitude of helical gear system increases with the increase of friction coefficient.