Research On Tooth Profile Synthesis And Mechanical Properties Of Double Rollers Planetary Transmission

With the rapid development of industrial robots in China,joint reducer has become the key to break through the core technology of robots.Common joint reducers of robots mainly include harmonic reducer and RV reducer.Among them,RV reducer is developed on the basis of cycloidal pinwheel planetary transmission.It has the advantages of heavy load,large transmission ratio,compact structure,etc,but the cycloidal wheel in RV transmission is difficult to process and high cost,which has become a key node restricting the localization of robot joint reducer.Therefore,this paper uses double roller planetary transmission with less tooth difference to replace cycloidal pinwheel planetary transmission,which not only meets the requirements of large transmission ratio,small volume and high precision of robot joint reducer,but also solves the problem of cycloidal wheel processing.Firstly,the structure and transmission principle of double roller planetary transmission with less tooth difference are introduced;the meshing curve of double roller planetary transmission with less tooth difference is established based on the envelope method of single parameter curved surface;the tooth profile equation of planetary gear is deduced based on the analysis results of curvature radius and the tooth profile replacement principle;in order to ensure transmission accuracy,the tooth profile optimization of double roller planetary transmission with less tooth difference is established.The optimization results of tooth profile parameters satisfying the design conditions are obtained by using particle swarm optimization(PSO)algorithm.The transmission error of the optimized results is analyzed to verify the feasibility of double roller planetary transmission with less tooth difference as precision transmission.Secondly,by introducing the concept of equivalent gear,the basic meshing law of double roller planetary transmission with less tooth difference is obtained;the transmission ratio of double roller planetary transmission with less tooth difference is calculated by using the principle of transformation mechanism;the correct meshing condition is deduced according to the meshing principle of tooth shape;the coincidence degree is calculated to obtain the continuous transmission condition;the pressure angle formula is deduced according to the meshing principle of tooth shape,and the influence of parameters is divided.Analysis.Thirdly,the load and stress of the meshing pair of double roller planetary transmission with small tooth difference are studied comprehensively.Mechanics model of meshing pair is established.According to deformation compatibility condition and moment balance condition of meshing pair,meshing force formula is deduced.The variation law of meshing force is analyzed and the influence of parameters is analyzed.Next,the stress analysis is carried out,and the formulas forcalculating the contact stress and the bending stress of the central gear pair are derived.The deformation analysis is carried out based on Hertz model.Finally,the prototype of double roller planetary transmission with small tooth difference and its performance test are carried out.The transmission ratio test,transmission efficiency test and transmission accuracy test are carried out.It is verified that the double roller planetary transmission with less tooth difference meets the requirements of large transmission ratio,stable transmission ratio,transmission efficiency and transmission accuracy of industrial robot joint reducer.