| Coal mining machine is one of the important equipments to realize the mechanization and modernization of coal mine production.In recent years,in order to fundamentally narrow the gap with foreign advanced level,achieve complete localization of the coal mining machine;achieve high reliability,high yield and high efficiency,improve the development of productive forces,the domestic research on the coal mining machine and put a lot of effort.Rocker arm transmission system is one of the most important parts of the coal mining machine.Through the gear transmission,the power of the driving system is transmitted to the drum to complete the coal cutting function.During the actual mining process,because the coal rock complex structure,cutting parameter changing,which makes the coal mining machine cutting unit load change sharply.The shearer is generally in the underground operation.Higher requirement on the reliability of shearer rocker transmission system is put forward.In order to accurately predict the reliability of coal mining machine rocker transmission system,and provide a theoretical basis for the reliability of coal mining machine rocker transmission system design,the coal mining machine rocker arm drive system is considered as the research object.Combined with the JC method,the reliability of the gear transmission system in coal mining is studied based on the theory of residual strength and stress strength theory.Based on the failure correlation theory and the copula function,the attenuation law of the dynamic reliability of the coal mining machine rocker arm transmission system considering the failure mode correlation and the component failure is obtained.The main research work is as follows:(1)The existing residual strength theory needs a large number of experiments to determine the unknown parameters,and is not suitable for large and long life coal mining machine rocker arm drive system.Based on the relationship between fatigue damage and strength,the residual strength model is established based on nonlinear fatigue damage accumulation theory.According to the relationship between fatigue damage and strength,the residual strength model based on nonlinear fatigue damage accumulation theory is established.Unknown parameters of the model can be determined without mechanical fatigue experiments.Considering the characteristics of the load,the residual strength model is established under two conditions of constant amplitude load and the load of two stages.The residual strength of two different materials under constant amplitude loading and two stages loading is analyzed,and the accuracy of the residual strength model is verified.(2)The statistical analysis of the random load is carried out by using the rain flow counting method.Based on the stress strength theory,the dynamic reliability function of coal mining machine rocker arm drive system gear is established.The dynamic reliabilities of gear tooth surface contact fatigue and tooth root bending fatigue are calculated by JC method.(3)Based on the reliability of coal mining machine rocker arm drive system gear contact fatigue and the reliability of tooth root bending fatigue,the dynamic reliability of coal mining machine rocker arm drive system gears under various failure modes is obtained by combining the copula theory.The reliability of the gear considering the failure mode correlation is calculated.(4)On the basis of the dynamic reliability of the components,the reliability variation law of the coal mining machine rocker arm transmission system considering the failure correlation of components is studied.The importance of considering the component failure correlation in the process of system reliability design is verified. |
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