| Heavy-duty railway locomotives play an important role in domestic resource allocation and cargo circulation due to large traction and high transportation efficiency.The gear transmission system is the key to the safe operation of locomotives.Previous studies on gear contact rarely consider the effect of temperature.In paper,based on the theory of gear meshing,tribology,heat transfer,hertz contact and finite element contact theory,the paper analyzes the steady-state thermal behavior of gear teeth under high-speed and heavy-load conditions gear dynamic contact,thermal-elastic coupling contact stress and thermal modification design of gear tooth profile,the main research work of the paper is as follows.(1)The locomotive gear transmission system parameters,used Solid Works and normalized three-dimensional model to establish a gear assembly,software instruction by dividing gear simplified model and model monodentate tetradentate assembly model,providing a geometric model of the finite element simulation analysis later.(2)The boundary conditions of the steady-state thermal analysis of the gear and the calculation of the convective heat transfer coefficient of the tooth surface are determined according to the basic theory of tribology and heat transfer,and the heat transfer model of the gear transmission is established,calculate the friction heat flow of the gear tooth according to the knowledge of gear meshing,analyze its distribution law along the meshing surface,used Ansys workbench steady-state thermal analysis module and statics module to analyze the temperature field and thermal deformation of the gear tooth body.The research shows that the maximum body temperature of the main and driven wheels of the motor at rated power is 94.44℃and 87.38℃,the maximum deformation is 34.5um and 32.4um,study the temperature field distribution of the gear body at different lubricating oil temperatures,calculate the gear bonding temperature according to the national GB/Z 6413.2-2003 standard,and the risk of tooth surface bonding damage under rated conditions is low.(3)The Saint-Venant principle gear simplified reasonably model,used Ansys meshing sweep method and used the partial region to obtain reasonable gear mesh refinement discrete model,teeth used a rotary joint to constrain and loading,used of transient dynamics module dynamic contact analysis,research and Hertz stress value obtained theoretical values are compared to verify,the finite element analysis shows that reliability.Transient and steady state thermal module and the subway joint kinetics module heat gear-elastic coupling simulation,the influence of the temperature field on the mechanical characteristics during the meshing process is analyzed,and it is found that the temperature increased the stress of the gears by 8.09% and4.86% during meshing and meshing respectively,and the stress decreased by 21.80 MPa when meshing at the pitch circle.(4)A complete tooth profile modification theory is proposed.Based on the involute curve equation and the coordinate conversion equation,Solid Works software is used to establish a parametric model of gear modification based on the Yoshio Terauchi equation in the temple.The finite element software is used to perform numerical simulation on the modified gears.The transient contact stress and deformation of the gears before and after modification are compared to investigate the effect of the tooth profile modification on the gear load distribution and the contact stress of the single and double teeth alternate meshing process as a result,it is found that the contact stress of the gear pair in the double-tooth engagement and double-tooth engagement positions is reduced by 1.31% and 13.45% respectively after modification,which can effectively reduce the stress impact when the gears are alternately meshed. |
