Mechanical Research And Structure Optimization Of Harmonic Reducer

With the rapid development of robot technology,especially the large number of applications of industrial robots.As the key core part of the industrial robot,the harmonic reducer is required for higher and higher performance.Harmonic reducer is transmitted by elastic deformation of flexible wheel,which has the advantages of small volume,strong bearing capacity and high transmission precision.Due to the periodic elastic deformation of the flexible wheel in the running process,the fatigue failure of the flexible wheel becomes one of the important factors restricting the application of harmonic reducer.Therefore,the research on the mechanical characteristics of flexible wheel becomes the key problem of harmonic reducer.The research work of this paper can provide some guidance for the research and development of harmonic reducer.The main research contents of this paper are as bellow:First of all,the principle,structure and characteristic of harmonic gear drive are introduced,as well as the deformation rule of the flexible wheel within the harmonic gear drive.According to the basic deformation formula of the flexible wheel,the displacement of each point of the flexible wheel under the action of different wave generators is calculated,and the deformation shape of the flexible wheel is obtained.Finally,the strength calculation formula of the flexible wheel is derived according to the load and empty load of the flexible wheel,which lays a foundation for the finite element analysis of the mechanical characteristics of the flexible wheel of harmonic reducer.Secondly,Solidworks is used to establish the solid model of the main parts of harmonic reducer.Using ANSYS finite element analysis software,combined with the characteristics of flexible wheel drive,the contact model of flexible wheel,wave generator and rigid wheel was established.The displacement and stress distribution contour during assembly were analyzed based on the model.According to the contact model between the flexible wheel and the rigid wheel,the load of the flexible wheel is simulated,and the curve of stress distribution and load change is obtained.The 3D optical deformation and strain measurement and analysis system was used to measure the assembly process of the flexible wheel.Result showed good alignment with numerical simulation which validated the FEM model.Then by changing the geometric parameters of flexible wheel model,different length to diameter ratio,tube wall thickness,gear ring width and the radius of the flexible wheel structure in the transitional area can be obtained.Different geometric parameters of contact model were set up based on those parameters and result in stress contours which map the change of the maximum equivalent stress at the dangerous area of the flexible wheel along with the parameters.The main geometrical parameters which affect the stress distribution of flexible wheel are optimized by orthogonal test and good combination of geometrical parameters was then acquired.Finally,the pre-stress modal analyses of the flexible wheel before and after optimization were performed using ANSYS software.With the inherent frequency and vibration mode of the flexible wheel indicated,the frequencies of each modal order were not closed to its working frequency which can prevent the resonance phenomenon.