Stability Analysis Of The Rotator Of The Overflow Type Ball Mill

Ball mill is a common crushing equipment in mine.With the development of the mining industry gradually toward the direction of cost reduction and efficiency increase,the ball mill,as an important mineral processing equipment,is more and more upgraded to large scale.With the increase of workload,the running performance of the ball mill has been more tested,and the running failure of the large ball mill often occurs.The operation failure of large ball mill often occurs in operation.In this paper,an obvious yaw of the rotating body occurs in a φ7.32×12.5m overflow double-drive ball mill.The working parameters of the mill and the supporting flow field of the rotating body related to the stability of the rotating body are analyzed numerically.Based on the comprehensive consideration of load characteristics and support stiffness,the factors affecting the stable operation of ball mill’s rotating body were analyzed from the perspective of dynamic reaction by means of computational modal analysis,harmonic response analysis and transient dynamics analysis,so as to provide reference for the design,research and fault maintenance of large ball mill.Firstly,according to the basic theory of the ball mill,the movement of the grinding particles and the force of the cylinder are described.According to the principle of simplification,the discrete element simulation model of ball mill drum is established in EDEM.By solving the model,the motion state of the particle,the force of the cylinder and the dynamic value of the starting torque are obtained.The generation of dynamic load in ball mill and its relation with particle motion are analyzed.The load conditions are provided for the three-dimensional transient lubrication flow field simulation of the hydrostatic main bearing and the dynamic characteristics analysis of the rotating body.Secondly,based on the actual physical model parameters and discrete element load calculation results,combined with the custom mesh movement algorithm,the three-dimensional lubrication flow field simulation analysis model of the hydrostatic main bearing was established in the Fluent software,and the pressure field of the lubricating oil film under different states was solved and calculated by the model.By comparing and analyzing the oil film pressure distribution results obtained from steady state and transient state calculation,it is found that the hydrostatic lubrication flow field under this working condition is accompanied by the generation of dynamic pressure effect,which leads to the main bearing can not fully resist the unbalanced disturbance force of the load.The unsteady running of the ball mill’s rotating body may be caused by the insufficient stiffness of the supporting flow field.Finally,in order to further reveal the dynamic working load and support stiffness on the stability of the ball mill of rotors flow field influence law,on the basis of modal analysis,and respectively by Shi Jia Jian harmonic load and dynamic load,under different supporting stiffness,the amplitude frequency response curve of solid of revolution,and calculates the dynamic curves of deflection,The analysis of the natural vibration characteristics of the rotating body and the dynamic analysis under dynamic excitation load were completed,and the influence of dynamic working load and support stiffness on the stability of the ball mill was studied.