Dynamics Analysis Of Ball Mill And Structure Optimization Of Gear Shaft Considered Foundation Vibration

As the large general grinding equipment,ball mill's working environment is complicated,so failures and damages are hard to avoid.The ?7.32×12.5m flow-type ball mill this paper studied was confronted with the problem that its pinion shaft was easy to break.In order to solve this problem,the ball mill's whole finite element model was established with the consideration of base vibration.Through test and simulation method,relevant key parameters had been identified.For one thing,dynamics analysis had been conducted to verify wheher the base had enough strength.For another,pinion shaft's stress distribution condition had also been calculated based on the accurate model.At last,by combining the agent model with intelligent optimization algorithm,pinion shaft's structure strength was optimized,realizing the purpose of reducing key parts' stress and enhancing the strength of pinion shaft.Firstly,when establishing the model,complex components and connections were dealt with several equivalences,key parameters' initial values were also presented.Secondly,based on the measured vibration modal parameters,taking oil film stiffness and foundation soil stiffness as correction parameters,the mill's finite element model was corrected with model updating method,which made the key modal frequency errors were reduced to 0.02%.At the same time,taking N222 E bearing as the example,a simulation method which based on local fine contact model to identify bearing radial stiffness was found,and it was proved to be reasonable by modal test.Therefore,this simulation method was applied to double row spherical roller bearings that the pinion shaft uses,guaranteeing bearing radial equivalent stiffness' accuracy to a certain extent in the absence of test.Based on above process,dynamics analysis had been conducted and it showed that the ball miss base was designed reasonable.In addition,a preliminary strength calculation was conducted and the result showed the pinion shaft's stress concentration area was consistent with the actual condition.Finally,selecting pinion shaft structure sizes as optimize parameters,taking volume as constraint,optimized the local stress using Kriging agent model and genetic algorithm,making the local stress was reduced by 21.9%,realizing the ultimate aim of strength optimization.