Study On Mechanical Properties Of Locomotive Traction Gear Based On Tribology

As a core of the locomotive transmission, the mechanical behavior and working performance of the locomotive traction gears have an important influence on the running state of the locomotive. Since the development of railway transportation is towards the heavy duty and highspeed, people have higher demands for the load-carrying capacity and transmission velocity of the locomotive traction gears. The load and velocity are the important factors which affect the tribological properties of materials for the locomotive traction gears. Therefore study on the mechanical properties of the locomotive traction gears based on tribology has an important realistic meaning on the development of the locomotives and rolling stocks in China. In many researches of the tribological properties for gears, the tribological behavior of gear materials in the meshing process is treated to be stable or is obtained by empirical formulas. Howerve, the locomotive traction gear transmission is a quite complicate dynamics process; the velocity and load of tooth surface are changed with time. Therefore the tribological properties of the meshing surface of gears are real-time.Based on the detailed analysis of the domestic and foreign studies on the gear tribology, considering the influences of load and velocity on the tribological properties of materials, the mechanical properties of the locomotive traction gears are researched systematically and deeply. The main researches and achievements are as follows:(1) Taken a certain locomotive traction gear as the research object, aimed at the materials42CrMo and17CrNiMo6, the pin-on-disk reciprocating friction and wear test which simulates the factual condition is done on the tribometer test machine. The friction coefficients under different loads and velocities are obtained. The test data are conducted by using multivariate nonlinear regression and significance test. Considering the influence of the load and relative velocity between the friction surfaces, the friction coefficient expression of the locomotive traction gear materials is obtained. The correctness of the friction coefficient expression is proved by groups of random tests.(2) Based on the obtained friction coefficient expression of locomotive traction gear materials, considering the effect of the load and velocity, the theoretical and simulation calculations of the contact stress for the test friction pair are conduct. The simulation results agree with the theoretical results. Considering the effect of the load and velocity, the temperature field of test friction pair is analyzed. The simulation results agree with the test results. It is found that complex and nonlinear friction and wear problem can be simulated by the finite element method, which provides a practical and effective way for the research of material tribological properties. (3) Considering the time variation of the tribological properties for the meshing point which is caused by the change of the contact force and relative velocity in the meshing process, the stress field of the locomotive traction gears under the starting and continuous running condition of the locomotive is analyzed and the variation laws of the contact stress and the friction stress are obtained. Through comparing the bending stresses on teeth root of the gear with friction and without friction, it is found that the influence of friction force between teeth on the mechanical properites of the gears is significant and it is necessary to research the locomotive traction gears from the tribological viewpoint.(4) The steady temperature field of the locomotive traction gears is analyzed. The distribution laws of the friction heat flux and the stable-state temperature on the meshing tooth surface are researched. Considering the change of the friction heat flux which is caused by the variation of the load and velocity in the meshing process of the gears, the transient and movable friction heat sources of different meshing position are set. The transient temperature distribution and variation law of every meshing node are researched, which provides a more accurate method for the calculation of the gear surface temperature.