| Locomotive transmission gear is the core component in the process of locomotive power transmission,and the reliability of its structure will directly affect the running safety of locomotive.With the improvement of the speed and load requirements of railway transportation in recent years,the gears of locomotives that have been in service for a long time will be in a high working environment,and excessive temperature may bring gear damage such as tooth surface bonding.Therefore,it is of great engineering significance to explore the distribution and size of the temperature field of locomotive gears and consider the thermal-mechanical coupling under different working conditions for the reliability evaluation,monitoring and maintenance of locomotive gears.In this paper,the transmission gear of an electric locomotive is taken as the research object,and the whole locomotive model is established and verified by dynamic simulation software.The vibration displacement diagram of locomotive transmission gear under wheel-rail excitation induced by rail corrugation with amplitude of 0.05 mm and wavelength of 150 mm is derived,and the vibration situation of locomotive transmission gear at different speeds is analyzed.It is found that the vibration frequency and vibration amplitude of driven gear are intensified with the increase of locomotive running speed.Combined with the geometric and physical parameters of locomotive transmission gear,the boundary conditions such as heat flux density and convective heat transfer coefficient in different regions of locomotive transmission gear are calculated by using the basic theories of gear heat transfer and tribology,and the influence of different traction motor speed and lubricating oil temperature on the boundary conditions such as heat flux density and convective heat transfer coefficient in different regions of locomotive transmission gear is explored.It is found that the heat flux density of locomotive transmission gear increases with the increase of locomotive running speed,and the traction motor speed and lubricating oil temperature have different effects on convective heat transfer coefficient in different regions of gear.Using ABAQUS finite element software to load the gear boundary conditions on the locomotive transmission gear model,the influence of different traction motor speed and lubricating oil temperature on the temperature field,the size and distribution of thermal deformation are obtained,and it is found that the highest temperature is located at the tooth root of the gear and distributed in a slender oval shape.The maximum deformation occurs at the intersection angle between the two end surfaces and the meshing surface,and the deformation decreases from the top of the tooth to the inner wall surface of the gear in turn.The structure field and thermal-mechanical coupling field are used to explore the distribution of temperature field,stress field and fatigue life of locomotive transmission gear with or without wheel-rail excitation,in which the thermal-mechanical coupling field adopts direct coupling method to make temperature and stress interact;Combined with the fatigue damage theory and stress analysis results,the fatigue analysis software fe-safe is used to predict the service life of a load spectrum with or without considering the influence of temperature.It is found that the fatigue life of locomotive transmission gear is obviously reduced after considering the temperature effect. |
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