Research On Friction Properties Of Transmission Mechanism Of The RV Reducer In Grease Lubrication

RV(Rotate Vector)reducer has many advantages such as compact structure,high precision and efficiency,which is widely used in precision manufacturing fields such as industrial robots.As the core component of the industrial robot,the friction performance of the RV reducer directly affects the efficiency and movement accuracy of the industrial robot.Therefore,according to the movement properties of the RV reducer,this paper analyzes the friction properties of its internal main transmission mechanisms,the cycloidal pinwheel mechanism and the planetary gear mechanism.The numerical calculation model of linear contact elastohydrodynamic grease lubrication is established,and the instantaneous lubrication properties of cycloidal pinwheel transmission and gear transmission are discussed,and the friction properties are analyzed.The main contents can be listed as following:(1)The transmission principle of the RV reducer is analyzed,and its transmission ratio is deduced.And then according to the closed power flow direction,the torque transmitted by the internal mechanism components of the reducer is deduced,which provides a basis for the analysis of the friction properties of the transmission mechanisms.(2)Using the Ostwald constitutive equations,an elastohydrodynamic model for linear contact grease lubrication is constructed.This model can be solved iteratively,by which some important lubrication parameters of grease film such as pressure and thickness distribution can be calculated,Meanwhile,the influence of different working conditions,structural parameters and non-Newtonic properties of grease on these lubrication parameters is discussed.(3)The geometric and kinematic parameters of the cycloidal pinwheel transmission are calculated and used to study the variation of load,entrainment speed and radius of curvature during a meshing cycle.An instantaneous elastohydrodynamic model for cycloidal pinwheel transmission is constructed,which is solved to get the pressure and thickness distributions of lip film at each contact position within a meshing cycle.These distributions can be used to recognize the lubrication state at different contact points and further define the zone for bad lubrication of cycloidal pinwheel transmission,and the friction properties of the cycloidal pinwheel transmission are explored.(4)The structural parameters,kinematic parameters and load distribution along the meshing line of gears are used to build the instantaneous elastohydrodynamic lubrication model of the spur gear transmission.By solving this model,the pressure and thickness distribution of grease film at each meshing point can be obtained.Then the lubrication state at each point on the meshing line can be determined according to film thickness distribution and film thickness ratio,and the friction properties of the spur gear transmission are explored.Finally,a program for analyzing the friction properties of cycloidal pinwheel transmission and spur gear transmission is developed,which would provide a convenient platform for calculating the lubrication parameters of the mechanisms in RV reducer.