Study On Tribology Of Starved-Oil Gear Transmission

In order to advance the green manufacturing of gear transmission and improve the transmission performances of gear, a series studies on gear working condition, starved-oil mechanism, wear, oil supply and engineering application of gear in transportation tool are carried in this paper against the starved-oil phenomenon of gear transmission.(1) To describe the working condition of gear pair, two basic factors, i.e. relative motion and load, are analyzed based on the gear engagement process. The relative sliding ratio expression, which is described by trasmission ratio, theoretical action line length and curvature radius, is developed for a convenient research on the influences of gear design parameters on the relative motion of two theoretical tooth profiles. Also, the manufacturing error of gear is simulated by means of a random function and the computation methods of the tooth engagement stiffness and the ratio of load distribution between theeth are both established based on a spring model after considering the manufacturing error. Taking SS8 locomotive gear as an example, the relative computation results show that the double tooth engagement stiffness value of the gear with comprhensive manufacturing error fluctuates between double tooth eagagement stiffness value and single tooth engagement stiffness value of the gear without comprhensive manufacturing error while the ratio of load distribution between teeth also fluctuates along that value of gear without comprhensive manufacturing error.(2) After the study on starved-oil phenomenon of gear pair is completed based on supply-demand relationship, starved-oil mechanism of gear pair is suggested that the starved-oil phenomenon will happen when the effective oil supply quantity is less than practical demend quantity; furtherly, it is pointed that the effective oil supply quantity is decided by the gear self-oil-supply ability and peripheral-oil-supply ability. Firstly, the computation expressions of the lubrication oil supply quantity and cooling oil supply quantity are both deduced respectively based on elastic dynamic lubrication theory and cooling principle. The influences of gear basic parameters are studied on the gear self-oil-supply ability are discussed respectively from two different aspects of load and speed. The influences of gear sturucture and relative location on peripheral-oil-supply ability are also discussed based on the supply efficiency. Some relative effective approaches are provided against starved-oil phenomenon of high speed gear or heavy load gear.(3) A computation model of higher pair friction work principle is suggested against the insufficient theoretical evidence usually used for current wear computation. That model can very resumptively express the friction wear law of sliding higher pair from the point of the energy view, and is suitable to the dynamic friction wear simulation of higher pair because of reliable theory evidence, simplification and practicality. A mathematical simulation software of tooth profile wear with convenience, overall factors and reliable results is developed. The wear of SS8 locomotive traction gear is computated and analyzed as an example. As a result, some measures relevant to the maintenance and design against gear wear are suggested.(4) A method of gear radial self-inhall liquid lubrication with self-owned intellectual property rights is introduced for the upright gear transmission with high speed and heavy load which is prone to starved-oil lubrication due to insufficient oil supply quantity under traditional oil supply mode. Some theoretical and experiment researches on oil supply of gear by means of screw pump, which is taken as an impetus, is made. It indicates after computating that the working cubage of screw pump is confined to both rotating speed and load while the influence of cooling on the working cubage has nothing to do with the rotating speed, and the working cubage should be designed according to maximum oil supply quantity along the action line of gear transmission, also the theory, the insufficient oil supply quantity will result in the starved oil state, is verified by experiment.Therefore, this paper manifests obvious theoritical value, practical value, and distinct guiding significance for tribology design of gear tansmission based on green manufacturing.