Research On The Cycloid Gear Profile Modification Of RV Reducer

Cycloid drive systemas a low speed output stage in the RV reducer,its movement accuracy and carrying capacity will directly affect the transmission performance of RV reducer.However,for the cycloidal drive system,the modification of the cycloidal gear profile is the key problem to determine the rotation accuracy and carrying capacity of the transmission system.Therefore,the study on the modification of cycloidal gear profile has been a hot topic in recent years.In this paper,a new modification method of eccentricity is proposed based on the forming principle of cycloid gear and its modification target.And the feasibility of the combination form of eccentricity,isometric and shift is analyzed from several angles.The main work and research results of this subject are as follows:1)From the aspects of rotation accuracy and carrying capacity,a comparative analysis on the effect of the commonly used combination modification method of cycloid gear profile.It is pointed out that the existing modification method can not meet the requirement of high load and low hysteresis at the same time,and propose an eccentricity modification method.The profile of cycloid gear modifiled by the eccentricitymethod could form the normal meshing clearance between the cycloid gear and the pin wheel.But due to the change of eccentricity,the tooth height of the cycloidal gear will change.Therefore,the eccentricity modification method can not be used alone in theone-teeth-difference cycloidal drive structure.It is necessary to be combined with the modification method of isometric andshift.2)Based on the precision measurement of the cycloid gear of the RV-40 E reducerwith the three-coordinate measuring instrument,the equation of cycloidal gear profile is derived by using the method of least square to fit the parameters of the measured cycloidal gear tooth profile.And then,by using the optimition function in Matlab,taking the obtained equation curve as the target tooth profileto optimize the cycliod gear profile formed by the three kinds of modification methods that are the combination methodsof "eccentricity + isometric + shift","equidistant + shift" and "equidistant + shift + rotation".Through the comparative analysis,the results indicate that the deviationbetween the curve obtained by the combined modification of “isometric + shift + eccentricity”and the fitting curve is smaller,compared to the combined modification method of “rotation+ isometric + shift” and “isometric+ shift”,whichillustrates the feasibility of the combined modification method of “isometric + shift + eccentricity”.3)Considering the shortcomings and deficiencies of the eccentricity’s selection of the existing cycloidalreducer drive,in oder to obtain the optimal value of eccentricity modification,this paper based on the relation of short amplitude coefficient and eccentricity in cycloidal pinwheel transmission of RV reducer,set up an optimization model of the eccentricity with the goal of obtaining the maximum bearing capacity,and discussed a numerical solution method for optimal design.And then established the finite element model of the multi body contact of cycloidal pinwheel tranmission,and carried the computer simulation analysis of the contact performance before and after the optimization of eccentricity.The anslysis result show that the optimized eccentricity’s contact stress between the cycloid and the pinwheel decreases about 12.6% compared with the customary,which further demonstrated that the optimized cycloidal pinwheel tranmission system has a greater load bearing capacity.These have a certain theoretical guidance value for the optimization of the cycloidal pinwheel transmission system.4)Taking the optimized amount of "eccentricity + equidistant + distance" combination method as the machining parameters to machine the cycloidal gear,that is used to replace the primarycycloidal gear in the RV-40 E reducer.The prototype after replacing the cycloid wheel is placed on the test platform to test the transmission error and geometric error.The measurement results show that the combination modification method of "eccentricity + equidistant + shift" combination basically satisfies the requirements of the transmission accuracy of the RV reducer.