| Fatigue life prediction of RV reducer for robots is of great significance to its safe use and structural design.In order to estimate the fatigue life of reducer components,the finite element model of RV reducer is established by finite element method,and the finite element static and dynamic simulation is carried out.The simulation results are analyzed and post-processed,as follows.Firstly,the parametric modeling system of involute cylindrical gear transmission is developed by APDL language,and the finite element model of the first-stage involute gear transmission is established by using this system,in which the generating principle of the spiral line and the root arc envelope curve is emphatically explained.Finally,the gear finite element model is obtained by sweeping method,and the contact and boundary conditions are established.Through finite element dynamic simulation,the course curve of maximum contact stress with gear rotation angle is obtained,and the change of course curve is affected by stress concentration phenomenon.The results of dynamic meshing of contact spots show that the meshing interference of three contact spots occurs in one meshing cycle.The simulation results of contact stress in single tooth meshing area are compared with the theoretical calculation values and have certain errors.The simulation has certain feasibility.Secondly,in order to carry out the finite element static simulation of the second-stage cycloidal pinwheel planetary transmission,the static finite element model is established by APDL language,in which the rigid beam truss joint planet carrier modeling method and discontinuous grid coupling are emphatically elaborated,and the contact and boundary conditions are established.The maximum Von Mises stress of cycloid wheel is obtained by finite element static simulation.The rigid and flexible region of cycloid wheel spoke is defined,and the contact spot distribution of cycloid wheel bearing hole at dangerous working conditions is obtained.The simulation meshing force of cycloid wheel is compared with the theoretical meshing force.The meshing force comparison curve results are different due to spoke deformation.Thirdly,in order to carry out the finite element dynamic simulation of the second-stage cycloidal pinwheel planetary transmission,the dynamic finite element model is established by APDL language,in which the modeling principle and method for simulating bearing connection,namely MPC(multipoint constraint equation method),application of hinge connection technology and other issues are emphatically introduced.The dynamic meshing force principle of cycloid pin wheel drive is analyzed,and the finite element dynamic simulation is carried out based on this principle.The course curve of maximum contact stress of cycloidal gear tooth surface changing with crank shaft angle is obtained through simulation,which verifies the simulation error of rotating arm simulation bearing and the dynamic modeling method has certain feasibility.Finally,the basic theory of fatigue life analysis is briefly summarized,with emphasis on the mechanism of contact fatigue failure of cycloid pin wheel drive and the dynamic change of cycloid tooth contact spot.The stress analysis of crankshaft,bearings and other parts is carried out.Combined with the stress calculation results obtained by finite element simulation,the fatigue life estimation value of RV reducer parts is obtained by theoretical calculation.The results show that the estimated contact fatigue life of cycloidal gear tooth surface is close to infinite life,and the life is the longest.Tapered roller bearings for crankshaft support have a limited life and the shortest life. |
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