Reliability Based Design Optimization Of Lifting Gear Reducer For Large Mining Excavator

As one of the main mining equipment of open-pit mining,large mining excavators have been widely used because of its large scope of bucket volume and high mining efficiency.However,the harsh working environment,complex load conditions and other unfavorable factors have seriously restricted the improvement of its reliability and safety.As the essential part of the hoist mechanism,the hoist gear reducer was the transfer of excavation power and main load bearing part.Its reliability and durability directly affect the work performance and security of mining excavators.Therefore,it is extremely meaningful to research the strength and reliability of hoist gear reducer.Actually the uncertainties are ubiquitous in the different stages during the life cycle of the hoist gear reducer,throughout its design,manufacture,use and maintenance processes.In addition the key components of the hoist gear reducer often have multiple failure modes,and the current research methods did not consider the correlation of multiple failure modes,it will lead to reliability analysis or optimization results contain error,even got the wrong conclusion.Based on above analysis,it is necessary to consider the uncertainties and failure correlation in establishing the reliability optimization design models,which is also the basis for ensuring its safe,reliable and effective running.In this paper,the hoist gear reducer of the WK-55 large mining excavator hoist mechanism is taken as the research object.The uncertainties and failure correlation is considering when establishing the reliability based design optimization models of the key components for the hoist gear reducer,the main research and achievements are summarized as follows:(1)Analyzed the uncertainties of the shafts,gears and box of gear reducer design,manufacture and use process,then chosen the appropriate method to quantify the above uncertain factors.(2)The existing researches on shafts and gears of hoist gear reducer did not consider the correlation of multiple failure modes.Thus,this paper introduced a copula function to describe the static strength failure and fatigue strength failure correlation,proposed an improved joint life distribution model to consider the above failure correlation.Similarly,perfected the joint life distribution model of the inter-meshing gears,finally,established the reliability optimization design model of gear transmission system to consider uncertainties and failure correlation and obtained the optimal value of design parameters.(3)In order to improve the static and dynamic performance of gearbox,and to avoid solving the complex dynamic equilibrium equation by establishing the parametric model of gearbox.Furthermore,using ANSYS software to carrying out simulative analysis of gearbox,and then obtained the radial basis function of the natural frequency,volume,deformation,stress.The further reliability based design optimization model and the verification of optimization results are carried out.