Analysis Of Dynamic Transmission Accuracy For RV Reducer In Robot

Cycloidal pinwheel RV reducer is a kind of planetary transmission which has two reduction stages with high performance and precision.It has the advantages of large ratio,high power density,high torsional rigidity,small backlash,well precision,good impact resistance,long life and so on.So it occupies the vast majority of the precision reducers market in industrial robots' joints.Dynamic transmission accuracy is a very important indicator of this reducer.Therefore,It is of certain theoretical significance and practical value to study RV reducer?s dynamic transmission accuracy and find out the main factors that affect the accuracy,so as to guide the design of high precision RV reducer.The main works of this paper are as follows:Based on the analysis of transmission principle and structure of RV reducer,a RV reducer prototype is designed with transmission ratio of 121,rated output speed 15 rpm and rated output torque 412 Nm.Then strength of involute planetary transmission in first stage and cycloidal gear drive in second stage as well as bearing life are checked.Then transmission efficiency and backlash are analysed.3D virtual model is created.Meshing stiffness of involute gear pair and cycloidal pinwheel pair are calculated by ISO6336 and Hertz formula respectively.Then bearing stiffness of arm bearing and support bearing are calculated.Based on the theory of dynamics of multibody systems,involute planetary gears of the first stage are regarded as rigid bodies,and cycloidal gears of second stage are regarded as flexible bodies.Rigid-flexible coupling dynamic model of RV transmission system is created after considering both internal and external incentives.The former rigid flexible coupling dynamic model is solved for dynamic response.Then the effects of profile modification of cycloidal gear,geometric error and load on dynamic transmission accuracy are investigated.The results show that negative composite modification could achieve better dynamic transmission accuracy compared with single modification and positive composite modification.Then precision grades of pin diameter,pin wheel diameter,center distance and eccentricity are suggested to be B2,IT2,IT6 and IT5 respectively.Finally,fundamental frequency of dynamic transmission error is double crankshaft frequency under load condition.The RV reducer prototype is manufactured.Then the experimental study on transmission accuracy is performed.The results show that tested backlash and maximum transmission error differ from the theoretical value by 1.7% and 5.6% respectively.