Computer Aided Tolerance Analysis And Optimization Design Of Assembly-Oriented RV Reducer

The RV reducer has the outstanding advantages of large bearing capacity,large transmission ratio,small backlash and small volume,and is an important component of the industrial robot joint drive device.RV reducers have many parts and high assembly accuracy,the backlash is usually less than 1'.There is a dimensional error in the actual machined part size,after assembly the cumulative error becomes larger,and the assembly yield is not high.The repairing methods mostly are used in the assembly of the cycloidal wheel and the pin wheel of the domestic RV reducer,which seriously affects the production efficiency.In this paper,the RV-40E reducer is used as the object,and the assembly dimension chain is established based on the assembly constraint relationship between the parts.In order to ensure the good transmission performance of the reducer,the short-amplitude coefficient is designed to refer to the eccentricity series of the cycloidal gear grinding machine.In order to compensate for the manufacturing and installation errors of the parts and have a certain radial clearance,the modification method of negative equidistant plus negative displacement is adopted,and the profile modification of the cycloidal wheel is optimized by MATLAB.The main design parameters affecting the backlash of the reducer are analyzed.The part processing cost is used as the objective function.The allowable backlash(?1')and the assembly dimension chain are used as constraints.The genetic algorithm is used to preliminarily design the tolerances of the parts such as the cycloidal wheel,the pin wheel,the crankshaft,etc.Based on the 3DCS three-dimensional tolerance analysis software,the tolerance simulation model is established,and the assembly performance of the RV reducer is evaluated by the eccentricity and the flank clearances between the cycloidal wheel and the pin teeth,the actual production assembly is simulated,the sensitivity analysis of the tolerance simulation model is carried out.Meanwhile the tolerance of the above parts is further optimized.Finally,the part error is reflected in the 3D model of the reducer.The virtual prototypes of the reducer are built based on CATIA software and imported into ADAMS for backlash simulation analysis to verify the tolerance optimization effect of the parts.The simulation results show that the backlash of reducer before the tolerance optimization is 0.002'?1.07',the backlash of reducer after tolerance optimization is 0.07'-0.85'.The effectiveness of optimizing design parts tolerance has been verified.Before the tolerance optimization,the eccentricity of the 3.78%reducer does not meet the design requirements.And the flank clearances between the cycloidal wheel and the pin teeth of the 26.7%reducer are less than 0.001mm or interference occurs.After the tolerance is optimized,the design requirement of the backlash and eccentricity of the reducer is qualified.The flank clearances between the cycloidal wheel and the pin teeth are greater than or equal to 0.001mm.And the assembly yield meets the technical criterion of "6?" reaching 99.73%.Although the processing cost of the reducer parts increased by only 6.08%,the cost of each reducer after assembly decreased by 22.24%.The sensitivity analysis results show that the biggest factor affecting the assembly performance of the cycloidal wheel is the shape modification error of the cycloidal wheel and the radius error of the pin tooth,followed by the circumferential cumulative error of the cycloidal wheel and the circumferential position of the pinhole,the last is the radial circle runout of the gear ring of the cycloidal wheel and the center circle radius error of the pin teeth distribution.The profile modification error of the cycloidal wheel,the radial clearance of the cycloidal wheel and the pin wheel,and the deviation of the pin tooth radius and the center circle radius of the pin teeth distribution need to be rationally designed.The coaxiality between the main bearing and the pin wheel has a certain degree of influence on the eccentricity,the flank clearances between the cycloidal wheel and the pin teeth.In this paper,the three-dimensional tolerance analysis model of RV reducer based on 3DCS established has theoretical guidance and practical application value for the localization of RV reducer,improving the actual production assembly yield and reducing the production cost of the reducer.And a method is proposed for optimizing the tolerance of RV reducer parts.