The Transmission Accuracy Analysis Of RV Reducer

RV(Rotate Vector) reducer is a high performance precision gearing, that developed from cycloidal pin-wheel transmission, it is the "hired" reducer of industrial robots because of the great speed ratio, high transmission efficiency, small hysteresis, low vibration, strong carrying capacity and high reliability, and it also applies to the electrical integration field, such as aerospace, numerical control machine and medical instruments. The development of mechanical and electrical technology puts forward higher requirements on the transmission precision of RV reducer. To get higher transmission precision of RV reducer, we must strictly control the transmission error. This paper analyzes the transmission error of the RV Reducer, and reveals its dynamic behaviors influence on transmission precision in nature.This paper analyzes the structure and working principle of RV reducer, the transmission ratio of the RV reducer is calculated by using the structure kinomatic inversion method, and the transmission efficiency is solved. The transmission errors generation mechanism and errors sources are studied. Based on the thought of equivalent model, analysing the impact of manufacturing errors, assembly errors, the damping and stiffness of gear meshing, bearing stiffness, clearance and micro displacement of the main components of the reducer, which have impact on the transmission accuracy. At the same time, the mechanics model of RV reducer system is established, and the force of main components are analyzed, based on Newton’s second law, the transmission error dynamic model of RV reducer is established. The solid part models of RV reducer are built, the quality and the moment of inertia of each part is solved. The damping and stiffness of involute planetary gear is calculated by using the theory of elasticity, iterativing the meshing damping and stiffness between cycloid gear which has been modified and the pin gear by using the computer programming, the equivalent stiffness of the bearings are calculated by Hertz formula.Solving the transmission error mathematical model of RV reducer by using the Runge-Kutta method, the transmission error curve of RV reducer is got. By simulating the different error parameters and comparing the effection of each error factor on the accuracy of RV reducer. It can be obtained that the correlated errors of the involute gear in one-stage gearing have little influence on the transmission accuracy of RV reducer. In the two stage of the transmission part, crank shaft cam eccentric error, cycloid crank shaft hole eccentric error, cycloid profile error and total cumulative pitch error, pin gear profile error and total cumulative pitch error have a great influence on transmission accuracy, which depend on the error size, the action direction and the combination mode. So the error factors in secondary transmission part should be taken seriously when a RV reducer is designed and produced, by controlling the greater impact factors, the transmission accuracy can be effectively improved.