| The Controlled Start Transmission(CST)is one of the soft starter to solve startup and load balancing issues of multi-motor driven scraper conveyor.CST is used to start the high and high power scraper conveyor drive system.CST is electromechanical-hydraulic integrated transmission system composed of gear transmission system and liquid viscous speed control clutch,which the load has time-varying and instability.The planet carrier of the planetary gear system is connected with the load sprocket,so the mechanical properties of planetary gear trains directly affect the service life and technical performance of CST.Therefore,the finite element analysis of planetary gear trains is carried out in this paper.A translation-torsion coupling dynamic model,three-dimensional model and a finite element model of planetary gear sets of CST are established.The static and modal analysis was carried out.Static analysis shows that planetary gears have sufficient static strength.The maximum stress value under rated conditions was 250.91 MPa,and the natural frequency have a high natural frequency,indicating sufficient stiffness and strength.Secondly,a nonlinear finite element model of planetary gear meshing dynamically considering deformation,friction and inertia forces is established,which was verified using the angular velocity,contact force time domain and frequency domain curves.The curves of dynamic contact force of each meshing pair and the stress course of each meshing position are obtained,which provided for the analysis of Load-sharing Characteristics and fatigue life of planetary gears.Thirdly,load-sharing Characteristics between the planetary wheels is research and the impacts of load-sharing measures,impact load,inertia load,rotating speed and contact parameters on the load-sharing characteristics were discussed.The contrast study shows that the center external gear floating improves the load characteristics remarkably.The impact load makes the load distribution between planetary wheels more uneven.Finally,the fatigue life of the gear is predicted by the Palmgren-Miner linear cumulative damage criterion and nominal stress method.The simulation results show that the minimum number of cycles of the planetary gear train under rated conditions is 1.32e7 cycles,and the first place where fatigue failure occurs is the gear meshing area of the inner ring gear.The effects of loading on fatigue characteristics,surface roughness,average stress correction method and other material performance sensitivities were analyzed.The impact loads will reduce the minimum fatigue life of planetary gear sets.The minimum fatigue life of planetary gears will show an exponential decline with the increase of overload. |
PDF Full Text Request