| Harmonic drive is a flexible transmission mechanism which has wide application,large transmission ratio,high transmission precision and compact structure.In operation,the harmonic drive realizes the conjugate movement between the flexspline and the circular spline through regular elastic deformation of the flexspline.Therefore,there are many complex and difficult problems in the design,manufacture and analysis of harmonic gears.There are inevitably different sources of errors in harmonic drive systems.These errors have complex effects on system performance.At present,there are few researches on error modeling and influence of error on system performance in harmonic gear transmission system.In this paper,the assembly error model of wave generator is established,and the influence and law of error on the performance of harmonic drive are solved and analyzed.This paper firstly summarizes and analyzes the source and characteristics of the error of harmonic drive.The wave generator assembly error,which has the greatest influence on the performance of the harmonic gear reducer,is selected as the research object,and the eccentricity assembly error of the wave generator and the deflection assembly error of the wave generator are defined,and four coordinate systems are established to describe the position relation and motion of the three main components of the harmonic gear.On this basis,a kinematic geometry model of wave generator assembly error is established.In the meshing performance analysis part,the position equation of the neutral point on the flexspline is firstly solved according to the error model.Then,the minimum backlash in the working process of harmonic drive is defined,and the 1-D search method is applied to solve the backlash distribution under different wave generator assembly errors.According to the constant twist angle between the circular spline and the flex spline,the deformation coordination equation of the flexspline body is established,and the load distribution of the harmonic gear under different assembly errors of the wave generator are solved.Finally,the influence of wave generator assembly error on meshing performance is analyzed.In the finite element analysis part,firstly the finite element model of the friction transmission harmonic drive is set up,and the friction equivalence of the finite element model is realized by optimizing wrap angle of friction drive with the two parameters of the friction coefficient and the interference amount.The stress and strain in the working process of harmonic gear are solved by the friction equivalent finite element model,and the maximum stress and the maximum displacement of the harmonic gear under the different assembly errors of wave generator are explored.In the end,an experimental platform for measuring the shaft motion and the transmission precision of the harmonic drive is designed,which can synchronously measure the motion of the input and output axis and the transmission precision of the harmonic drive.This paper designs the experimental scheme and carries out the structural design of the experimental platform according to the selection of key components.Finally,the experimental platform is assembled and measured.The experimental environment is built for subsequent research on the relationship between shaft motion and transmission accuracy.The assembly error model of wave generator is established in this paper.The motion geometry,finite element and deformation coordination equation are used to solve the backlash distribution,load distribution and the stress and strain of the flexspline under the influence of the assembly error of the wave generator,and the influence of the assembly error of the wave generator on the performance of the harmonic gear is analyzed.This paper reveals the complex influence of error on the performance of harmonic drive,and provides some ideas and methods for analyzing the performance of harmonic drive under the analysis error.And the experimental platform is built for subsequent research on the relationship between shaft movement and transmission accuracy.Because of the complexity of harmonic drive,there are still many problems to be studied and explored. |
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