Tooth Profile Design And Comprehensive Performance Optimization Of Harmonic Drive Driven By Conjugate Parameters

Due to the advantages such as high transmission accuracy,strong bearing capacity,small volume,light weight,harmonic drive reducer has been widely used in the space mechanism,national defense weapons,industrial robots,and other high-end equipment.In the field of high-end applications,the reliability life,accuracy,and performance consistency of domestic harmonic drive reducer still have a certain gap with the international advanced level.The lack of a set of parametric,serialized,and standardized harmonic drive tooth profile design,analysis,and evaluation methods are one of the fundamental reasons.This paper aims at the forward design,analysis,and optimization of harmonic drive reducer serialized product development,based on meshing,contact,and lubrication mechanics theory,has proposed a method for tooth profile design and comprehensive performance optimization of harmonic drive driven by conjugate parameters.The main contents of this thesis are summarized as follows:(1)Based on the basic hypothesis of harmonic drive,the geometric relation model is established,and the rotation angle relation of harmonic drive is deduced.Taking the profile curve of wave generator as input parameter,a harmonic drive tooth profile design method is proposed based on the pinion and rack motion trajectory mapping and the Willis theorem.The influence of conjugate parameters on the meshing characteristics of tooth profile was studied.The results show that the tooth profile design method can solve the tooth profile of quadratic conjugate and two-point conjugate simultaneously without parameter optimization,and the maximum meshing domain can be obtained,which is easy to realize the parametric and serialized design of the tooth profile of harmonic drive.(2)To avoid meshing interference,considering the flexspline deformation angle and machining feasibility,the design methods of the spatial tooth profile with inclination and spatial straight tooth profile are proposed.The meshing characteristics of the two spatial tooth profiles are compared and analyzed.The results show that the spatial tooth profiles engage mainly in the design section,and the uneven distribution of meshing backlash in the gear direction has an important effect on the actual contact line and meshing force of the gear teeth.(3)Considering no-load backlash distribution and the flexspline nonlinear deformation under loading conditions,based on the circumferential spatial flexibility matrix,the calculation model of spatial tooth profile contact region and meshing force distribution of harmonic drive is established.The influences of different modification methods and conjugate parameters on meshing force distribution are analyzed.The results show that the empirical formula of meshing force distribution is no longer applicable to double-circular-arc tooth profile.The spatial inclination tooth profile has better meshing characteristics and torsional stiffness characteristics.With the increase of load,the meshing teeth increase,but the amplitude is not significant.The main reason for the nonlinear increase of meshing force and torsion angle of circular spline is the increase of meshing contact area.(4)Considering the influence factors of tooth surface load,contact comprehensive curvature radius,and relative motion,a mixed lubrication model of the meshing tooth surface is established.The influences of conjugate parameters,spatial tooth profile modification,and working conditions on tooth surface lubrication characteristics are discussed.The results show that the decrease of the radial deformation coefficient of the wave generator can increase the number of meshing tooth pairs and reduce the meshing force of tooth surface,but also lead to the decrease of the integrated radius of curvature and the relative velocity of meshing point,and finally lead to the decline of lubrication performance.Therefore,the influence of conjugate parameters on meshing and lubrication characteristics should be considered comprehensively when designing the tooth profile.(5)Considering the meshing,contact,and lubrication mechanics theoretical model and test data,the mapping relationship and coupling mechanism between the design conjugate parameters and the spatial meshing characteristics of multiple teeth,contact and lubrication characteristics of the micro transmission interface,and macro comprehensive transmission performance of the harmonic drive is studied.The control and optimization method of harmonic drive reducer's transmission performance is proposed.