Research On Calculation Model Of Time-varying Meshing Stiffness Of Planetary Gear Based On Full Tooth Profile

The planetary gear has strong points such as large load,high transmission ratio,etc.,so it is widely used in various reducers and speed increasers.Planetary gear often breaks down in bad working environment.The most frequently failure types of gear is pitting.However,the weak pitting fault signal is often ignored in the gear system fault signal and causes more serious accidents.Stiffness excitation is the most important excitation of gear dynamics system,which is of great significance for the research of gear pitting failure mechanism.Therefore,it is extremely requisite to study the computational model of TVMS(Time-varying mesh stiffness).The main research contents are as follows:(1)A computational method for the full profile equations of internal and external meshing gears is proposed.Through the analysis of the process of machining external gears by rack tools,the involute part and the transition arc part of the tooth root of the external gear are obtained.The displacement of the tool is a parameter equation,and the comparison with the standard involute equation shows the correctness of the tooth profile equation obtained in this paper.Through the analysis of the process of machining external gears and internal gears with gear cutters,the parametric equations of the involute and tooth root transition arc part with the angular displacement of the gear cutter as the parameter are obtained.(2)A TVMS computational model of planetary gears based on the full tooth profile is proposed.The meshing stiffness of two kinds of planetary gears is analyzed and calculated.The reason why the results are different from those of the previous simplified tooth profile model is explained,which shows the correctness of the model in this paper.(3)The location,size and depth of pitting pits are indicated by u,v,r,δ.With the tooth surface pitch line as the normal distribution center,imitate of pitting spread on tooth surface using normal distribution,and by controlling the pitting pits.The diameter and depth simulated four degrees of pitting corrosion,computational the gear meshing stiffness at different levels of pitting,and the influence of the mesh stiffness is analyzed.(4)Introduced the calculation method of effective contact tooth width when two intermeshing gear teeth have pitting failure,and compared the effect of single-wheel tooth pitting and multi-wheel tooth pitting on meshing stiffness in the same meshing pair.Combined with the phase relationship of the planetary gear system,the stiffness changes of each meshing pair are analyzed when pitting corrosion occurs in a single gear tooth and multiple gear teeth appear pitting.(5)According to the full tooth profile equations of internal and external meshing gears obtained in Chapter 2,solidworks was re-developed using VB language,and a software was obtained that can obtain three-dimensional models of internal and external meshing gears according to user input to classify gear parameters.And the finite element analysis uses the obtained 3D model,It was proving the effectiveness of the stiffness computational model.