Study On The Precise Modeling Method Of Gearbox Transient Dynamics

With the development of gearbox in the direction of high speed and heavy load,the requirements for vibration noise,light weight,and reliability are also increasing.Therefore,it is very necessary to seek a precise modeling method to predict the dynamic characteristics of the gearbox accurately,and to provide a theoretical basis for its vibration reduction,noise reduction and structural optimization design.A cylindrical gearbox is selected as the research object with the support of the National Science and Technology Support program(Project No.2013BAF01B05).The research on the precise modeling methods for gear pairs and bearings is carried out,and the inherent characteristics,transient dynamic characteristics,and vibration test of the gearbox are also studied.The major contents and results are as follows:Firstly,the dynamic excitation in the process of gear transmission is analyzed.Based on the Hertz contact theory and the structural characteristics of deep groove ball bearings,the formula for calculating the nonlinear stiffness of the bearing is derived.Based on the proposed simplified dynamic model of the bearing and the calculated stiffness curve of the bearing,the precise modeling method of the transient dynamics of the rolling bearing and gear pair is studied,and the establishment of the precise model of the gearbox is completed.The free modal analysis of gearbox is carried out to obtain its natural frequency and vibration mode based on the LANCEZOS method and the bonded contact theory.Moreover,the experimental modal analysis of gearbox is carried out by using the method of force hammer excitation.Comparing with the simulation results,the modal analysis model of the gearbox is verified and corrected.Using the proposed precise dynamic modeling method of gear pairs and bearings,the three-dimensional contact finite element model of gearbox is established under the consideration of non-linear factors such as time-variable meshing stiffness,meshing impact,tooth surface friction,and bearing stiffness.Through transient dynamic analysis,the stress state of each component of the gearbox and the vibration characteristics of the box under rated working condition are obtained.At the same time,the dynamic characteristics of the small gearbox under different rotational speeds,different bearing clearances and geometric eccentricity errors are also studied.Finally,the vibration test bench is built to test the vibration response of the gearbox under different working conditions,and the acceleration response curve of the reducer is obtained by experimental methods.Comparing with the simulation results,the effectiveness and accuracy of the proposed method for precise modeling of gearbox transient dynamics are verified.