The Research On Thermal Behavior And The Modification Design Of High-speed And Heavy-Power Gear System

With the increasing progress of industrial technology, high-speed and heavy-power transmission equipments have been widely used in every field. The thermal behavior has been main constraint of its development. The research subject in this study is high-speed and heavy-power gear system. The thermal behaviors, that including distribution of bulk and flash temperature, thermal deformation, thermo elastic coupling, scuffing load capacity and dynamic thermal characteristics and so on, were studied based on the heat transfer theory and Hertzian contact theory with the numerical simulation method and thermal elastohydrodynamic lubrication (TEHL) method. It provides the basis for thermal design and verification of high-speed and heavy-power gear system. The main research contents are as follow:(1) The prediction method of accurate temperature fields of gear systems was proposed based on Hertzian contact theory and heat transfer theory by means of FEM, numerical simulation and TEHL. The more accurate bulk temperature distribution was obtained based on the FEM under the consideration of the pressure-viscosity-temperature and density-pressure-temperature effect in heat transfer coefficient. The distributions of flash and contact temperature along the action line were obtained by solving TEHL equations, and bulk temperature was chosen as initial temperature. The bulk temperature was verified and modified in FZG tester. The influence of pressure angle, displacement coefficient and profile modification on the distributions of bulk and flash temperature were studied.(2) The distribution of the contact line length and its variation over axial contact ratio was obtained based on meshing surface method and the design method of helical gear was put forward to reduce the vibration and noise. According to meshing stiffness and load balance equation, the load distribution of helical gear system was obtained and it provides the basis for analysis of helical gear temperature fields and thermal elastic coupling. The characteristic coordinate of helical gear system was established to simplify the helical gear design and verification process. (3) The thermal deformation of the gear system was calculated with FEM and numerical method. The influence of thermal deformation on load and transmission error (TE) distributions was studied. The stress distributions of contact zone under static and dynamic condition were studied. The thermo elastic coupling analysis of gear system was carried out to study the stress, thermal elastic deformation and TE distribution in meshing process based on the FEM. The influence of temperature on contact behavior of gear system was analyzed. It provides a reference for tooth profile modification.(4) The scuffing load capacity of gear system was studied through the TEHL theory. The evaluation criteria and design method of scuffing load capacity were put forward. The temperature of contact point varied over time was calculated with numerical simulation method. The lubricating properties and thermal effects of contact zone were carried out based on TEHL. The influence of geometric and lubrication parameters on TEHL characteristic was studied. The flash temperature and oil film thickness distributions were obtained to evaluate the scuffing load capacity. A comprehensive application analysis of the scuffing load capacity between Blok and TEHL theory was carried out. The transient TEHL analysis of spur gear system was carried out to evaluate the transient scuffing load capacity based on dynamic load.(5) The profile modification mechanism of gear system was studied based on the distribution of stiffness and load balanced equation. The load and TE distribution under different parameters was obtained. The optimum gear profile modification curve was determined according to thermal deformation and elastic coupling analysis results. The selection principle of tooth profile modification parameters was put forward based on dynamic analysis.(6) The distribution of dynamic load and dynamic characteristics of gear system were calculated based on time-varying stiffness and dynamic model. The research on dynamic load factor varied with speed and damping variation was studied. The amplitude frequency characteristic and resonance problem were studied. The vibration characteristics under different conditions were implemented through the FZG gear tester.This research was financially supported by the National Natural Science Foundation of P.R. China (No.51275035).