| The gear is the key component of the transmission system.The demand for the strength,precision,noise and compactness of the transmission gear is increasing in modern industry,especially in the field of new energy vehicles,aerospace and other fields,all these require that the gear transmission has the characteristics of light weight,reasonable structure,long service life and high reliability.During the gear transmission,the speed of the two tooth meshing points is different,which causes relative slipping between the teeth,resulting in a lot of heat,which makes the temperature of the meshing point rise,resulting in the deformation of the tooth surface and the accuracy of the engagement of the gear surface,which will cause the failure of the gear in severe cases.The application of surface modification technology to gear surface can reduce the friction coefficient of gear engagement,improve the wear resistance and bearing capacity of gear surface,and improve the transmission performance of gear.In this paper,the distribution of steady temperature field,the friction and wear properties of the coating,the wear and wear mechanism of the coating and the transmission performance of the coated gear were studied.The main research work in this paper is as follows:(1)According to the basic theory of gear temperature field,the thermal conduction differential equation of gear was derived.According to the demand of gear steady temperature field analysis,considering the load distribution and heat distribution,the frictional heat flux density of gear pairs at different meshing positions was accurately calculated.The heat dissipation of each surface of the gear was analyzed and the convective heat transfer coefficient of each surface of the gear in the process of operation was calculated.(2)According to the finite element boundary condition theory,the boundary conditions of each surface of the gear in the finite element heat analysis were detailedly discussed.The finite element model of the gear single tooth was established in the finite element software,and the steady temperature field of the gear before and after the transformation of the manganese phosphate conversion coating was solved.The change law of steady temperature field of gear in two operating conditions of variable speed and torque was analyzed.(3)The conversion coating of manganese phosphate was generated on the standard specimen,the friction and wear properties of the coating were tested on the friction and wear tester.The change of friction coefficient with time before and after coating treatment was compared and analyzed.The microstructure and surface phase structure of the manganese phosphate coating were analyzed.The wear surface of the coated specimen after friction and wear test was analyzed by using the energy spectrometer.(4)The FZG standard gear before and after treatment of manganese phosphate conversion coating was tested,and the influence rule of coating treatment on gear box lubricating oil temperature and gear vibration characteristics was analyzed.The manganese phosphate conversion coating was applied to the gear of the automatic transmission,and the gear dynamic cycle test rig was built to evaluate the transmission performance of the transmission gear processed by the coating. |
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