Analysis Of Geometric Backlash And Optimization Design Of Cycloid Gear For RV Reducer

The RV reducer is the key rotary support components of industrial robot,it has a high precision movement,large transmission ratio,small backlash and large rigidity,compact structure,long service life and so on a series of advantages.In recent years,with industrial robots become high speed,high precision,heavy load,lightweight and intelligent direction,the demand for high precision RV reducer are increasingly prominent.At present,our country still cannot design and manufacture high precision RV reducer to meet the requirements,the market share all monopoly by foreign companies.So study about the parameters design and manufacturing method of the high precision RV reducer has the very important significance.Transmission error and geometric backlash are two important index for high precision RV reducer,they have a direct influence on the feedback control system of robot,and also affect the system dynamic quality.This paper mainly analyzes the parameter factors affecting its geometric backlash and their values.The RV reducer consist of first level cycloid planetary transmission,second level cycloid pin gear planetary transmission and the output mechanism.Based on the analysis of its transmission principle and structure,we known that cycloid gear needle wheel planetary transmission mechanism is the key part,the parameters of cycloidal planetary transmission mechanism among the influence factors impact on the transmission error and backlash have the larger proportion.This paper is based on the known general equation and the basic modification method for cyloidal tooth profile,on the purpose of minimizing backlash,select the negative isometric and negative shift modification method to get it’s tooth profile,and with method of tooth profile optimization model to get the best modification to the clearance.The parameters at all levels drive mechanism have different influence on the geometric backlash of RV reducer,through the analysis of the relationship of reducer parameters with geometric backlash,established its geometric backlash calculation mathematical model.With MATLAB software platform for the development tool,using the Monte Carlo’s method to produce random number,developed different simulation parameters of random values in geometric backlash calculation program;And with the minimum geometric backlash as the goal,developed the RV reducer parameters optimization program.As an example in the RV-40E-121 type reducer,,the first level involute planetary gear transmission to choose 6 level precision level standards,strict control of the turning arm bearing radial clearance of third level output mechanism,calculated a set of optimal values of the parameters in the cycloidal planetary transmission mechanism by optimization,considering the sensitivity index and the parameter error on the RV reducer backlash specific impact,explore a method that get reasonable tolerance zone and its deviation of each parameter in the cycloid planetary transmission mechanism;The average geometric backlash by Monte Carlo simulation calculation is less than 1’.For further reasonable tolerance zone of the RV reducer has the practical significance.By the simulation result shows that the recommended tolerance zone still cannot guarantee all random parameters combination plan of the RV reducer geometry backlash to meet the strict requirements is less than 1’.Therefore,on the basis of the above parameters in the tolerance zone,further explore to get through the tiny dislocation structure of two cycloid gear in the assembly method to reducing the RV reducer backlash,can greatly increase the probability that the RV reducer geometric backlash is less than 1’.By dislocation design,can appropriately relax cycloidal meshing pair of the tolerance zone of each parameter,and reduce the manufacturing cost.