Strength Analysis And Fatigue Life Evaluation Of Oversize Mine Ball Mill Shell

As the key equipment for second-class grinding, ball mill is widely used inchemical engineering, metallurgy, construction materials, electric power and otherindustries. Being the main working part of ball mill, shell suffers prodigious impactloading which changes continually. Meanwhile, shell is operating under the scurvinessworking environment. Therefore, the strength and fatigue life of shell play a fatal rolein working performance of ball mill.In this dissertation, super-huge type overflow mine ball mill shell is taken as thestudy goal. The model of ball mill shell was simplified according to real workingconditions and the finite element model of the mill shell has been built. The finiteelement computing methods for the strength of mill shell under various were studied.And compared with experimental data, the applicability of computing methods wasanalyzed. The results showed that the computing methods considering the bolt reloadwas more close to the experimental data and distribution of stress of ball mill shell wasmore real.Based on modal analysis theory, finite element model of ball mill shell isanalyzed by means of carrying loading. First ten steps of modal shape and frequenciesof ball mill shell were obtained. By comparing the frequencies with working frequency,vibration characteristics of ball mill shell were analyzed. The analysis revealed that theinherent frequency of ball mill shell was much higher than working frequency, andthere was no resonance occurred. But crack could happen in the middle of shell mucheasier than in other areas. The structure and stiffness were inferior here.On the basis of the finite element analysis on strength of ball mill shell, fatiguelife calculation of shell was carried out in view of linear cumulative damage theory.The result showed that the minimum value of safety factor was2.3965, and fatigue lifeof shell met the maximum value. The calculation results suggested that the shellperfectly met design requirement, and use ratio of materials was relatively low which means space of further optimization of the structure is large. It was also found that theweak part of shell was inner side of shell near feed end. Therefore, the furtheroptimization of the shell structure could be done.In this dissertation, the strength of ball mill shell was calculated and severalcomputing methods of strength of ball mill shell were analyzed by Comparing withexperimental data. Moreover, the mode analysis of shell was carried out, and fatiguelife of shell was analyzed based on strength calculation of shell. All the researchresults can be theoretical basis and reference for optimal design of structure of ballmill shell.