Error Modeling And Tooth Profile Modification Of Cycloid On RV Reducer

The industrial robots have urgent demands for reducer with high accuracy andhigh efficiency. The whole study process was conducted by the financial aid of thenational high technology research and development projects. According to thestructure and transmission characteristics of the RV reducer, error modeling methodand cycloidal tooth profile modification technology of the reducer have been studiedin this paper. The main contents are as follows:As to the geometric characteristics of cycloid drive, the tooth profile formula ofcycloidal gear is established by adopting the inversion method, firstly. Then with thestudy of characteristics of the curvature radius and pressures angle have, theinfluences of the geometric parameters on the curvature radius and pressures anglehave been analyzed. The undercutting conditions of the cycloidal tooth profile havebeen derived. The calculating method of the pressure angle between pin tooth andcycloid gear with multi-teeth meshing has been preliminary studied, which providesreference for the strength design of the components of the reducer.As to the equivalent kinematic model, according to the structure characteristicsthat the input and output of the cycloid gear share one crank shaft and the output trayand tied are the same component, the equivalent kinematic model of the reducer hasbeen studied and established. In this model, the crank shared by the input and outputof the cycloid gear is kinematical equivalent to a parallelogram linkage. And with themethod of low pair replacing high pair, the high pair of gear meshing is transformedto equivalent low pair mechanism with revolute joint and virtual link. In the end thereducer mechanism is equivalent to multi branched loop mechanism which can revealthe instantaneous movement characteristics and provides an effective method for thekinematic study of the reducer mechanism.In the aspects of error model, based on the kinematic equivalent mechanism ofRV reducer, the method of loop incremental theory is used to establish analytical errormodel for the analysis of the mechanism output error. This model reveals not only theanalytical corresponding relationship between original errors of components and themechanism output error by explicit equation, but also the error transfer process of aparallelogram link mechanism and the coupling relationship between feedback errors original errors of components. It offers an effective method in the precision analysisand modeling of the complicated planetary gear set.In the aspects of generating method, the influence of geometric errors to theshape of cycloidal profile is revealed by the cycloidal profile error model which isconstructed by the rotational vector method. Based on the principle of designmethodology, the error combination of ideal cycloidal modification profile withgenerating method is obtained which concludes that negative deviation of the radiusof needle tooth and distribution of needle tooth is more advantageous to the optimalcycloidal modification profile.In the aspects of forming method of the cycloidal profile, basing on the theory ofsegmented modification, the cycloidal gear can be divided into working andnon-working tooth profile. General method which can be used to determine the regionof working tooth profile is presented on the principle of optimal of transmissionperformance. The modification equation of working tooth profile is constructed byapplying the angle modification. The non-working tooth profile is constructed byspline function. The modification equation of tooth profile which can be generallyused to choose the region of working tooth profile, backlash, bottom clearance andaddendum clearance according to different requirements of actual situation, workswith engineering application value.