| This topic comes from the National High Technology Research and Development Program(863 Program),the development and industrialization of robotic high-reliability precision harmonic reducer series products(2015AA043001).Harmonic transmission is widely used in high-precision transmission fields such as robots,aircraft,radar,medical equipment,etc.due to its unique advantages such as high precision,small size and large transmission ratio.In order to improve the meshing characteristics and fatigue strength of harmonic transmission devices,this paper focuses on the multi-parameter multi-objective optimization,spatial tooth profile modification,flex wheel stress and other key issues,and the double-circular tooth profile with uncut tangent is taken as the research object.Based on the harmonic eccentricity theory of harmonic drive with precise angle relationship,the parameter optimization and tooth profile modification are the focus of research.The conjugate interval and the degree of "double conjugate" and the soft wheel stress are used as evaluation indexes to MATLAB parameters.A series of research work by means of simulation and finite element method.1 The basic theory of the harmonic tooth shape is expounded.The basic flow of the harmonic plane profile design has four steps.1 Master the composition,working principle and transmission ratio calculation of harmonic transmission;2 Defining the harmonic transmission coordinate system on the basis of the assumptions,and establish the harmonic transmission geometric relationship by combining the neutral curve of the flexspline with the precise angle of the harmonics.Model;3 The envelope method and kinematics method,the harmonic drive engagement theory is derived;4 the non-common tangent double arc tooth profile is proposed,and the meshing theory is used to solve the conjugate tooth profile,and the arc fitting is performed.2 Based on the harmonic drive meshing theory,the conjugate interval and the conjugate tooth profile are analyzed,and the rationality of the double-arc tooth profile without the common tangent is proved.Taking the meshing parameters as the design variable,the toothed no-load continuous meshing and the degree of "double conjugate" as the objective function,the multi-parameter multi-objective harmonic drive optimization model is established,and the single parameter analysis and multi-objective optimization are performed to obtain the optimal function.The solution shows that the optimization method can effectively improve the meshing characteristics of the harmonic gears,so that the backlash between the teeth is small and uniform.3 Then,the principle of shaping the tooth profile of the double-arc flexspline is proposed..Compared with different modification schemes,the middle wheel height and low end flexspline tooth profile without secondary machining are determined.The flexspline diameter calculated by finite element method is combined.The displacement reveals the relationship between the radial deformation of the cam and the shape of the flexspline tooth profile.It is found that after the modification,the flexspline and the circular spline have no tooth profile interference in any section,and the maximum meshing depth is ensured.Improve the carrying capacity of the flexspline.4 In order to explore the influence of parameters of tooth profile on the flexspline stress,the assembly and loading state of the harmonic gear are decomposed into three analysis steps,and the tooth profile parameters and stress response based on the multi-tooth nonlinear contact finite element method are established.The surface model,the research results show that: Circular spline constrains the deformation of the flexspline generated when the wave generator is installed,which leads to a sharp increase in the flexspline stress;Because the harmonic gear transmission is a multi-tooth meshing transmission,the meshing interval is large,When the load is distributed to multiple pairs of contact teeth,each tooth pair bears less load,so the load has less influence on the deformation and stress of the flexspline.According to the model analysis,the influence of single factor on the flexspline stress can effectively guide reasonable selection of the tooth profile parameters of the flexspline. |
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