| The herringbone planetary gear transmission system is the core subsystem of modern high-speed and heavy-load mechanical equipments.The scuffing phenomenon caused by the continuous increase of tooth surface temperature during transmission contact has become one of the main failure modes of the equipments.Its failure often occurs instantaneously and unpredictable,which restricts the service life and reliability of the equipments.The contact characteristics of herringbone gear tooth surfaces transmission determine the anti-scuffing bearing capacity of herringbone gear.The contact characteristics of herringbone gear meshing transmission are unknown.At present,there are few studies on the scuffing bearing capacity of herringbone gear transmission systems and there is no mature and unified analysis method.In the existing research,the influence of tooth surface contact characteristics on the scuffing bearing capacity is mostly ignored.At present,it is urgent to carry out more accurate and in-depth analysis and research on the anti-scuffing bearing capacity of herringbone gear transmission systems to improve the prediction accuracy and reliability.In this paper,the single-stage herringbone gear is taken as the research object,and the following research is carried out :(1).The mixed thermal elastohydrodynamic lubrication characteristics of herringbone gears are modeled and analyzed.Considering the influence of elastic deformation of asperity on rough surface,the calculation methods of center film thickness and minimum film thickness of line contact mixed thermal elastohydrodynamic lubrication are improved based on Reynolds equation and viscosity-pressure-temperature effect of lubricating oil.According to the given geometric parameters of gears and material parameters of lubricating oil,the relevant parameters of herringbone gears under mixed thermal elastohydrodynamic lubrication are solved.(2).Considering the viscosity-temperature and viscosity-pressure effect of lubricating oil,and the load sharing theory of tooth surface.The tooth surface contact temperature algorithm is improved,and the calculation model of tooth surface contact temperature is established.The distribution of friction heat flux and contact temperature along the meshing line is revealed.The effects of torque and rotational velocity parameters,tooth surface roughness and different types of lubricating oil on tooth surface contact temperature are analyzed.(3).Based on the principle of herringbone gear meshing geometry,the contact line length,tooth surface contact pressure and sliding distance distribution are calculated.According to the advantage of the degradation entropy generation theorem in predicting the wear degradation under variable load conditions,the thermodynamic wear model of herringbone gear is established.The wear distribution caused by friction on the tooth surface of the driving and the driven gear under mixed lubrication was obtained and compared with the calculation results of the Archard wear model.In addition,the influence of the tooth surface contact state on the calculation results is further discussed in the analysis process.(4).The numerical simulation model of herringbone gear scuffing considering the influence of tooth surface friction and wear is established,and the scuffing bearing capacity of herringbone gear under FZG scuffing test standard is simulated.The variation trend of tooth surface friction coefficient,contact temperature,oil film viscosity and oil film thickness with time is analyzed.The results of the scuffing failure stage calculated by the ISO standard and the improved algorithm in this paper are compared,and the influence of tooth surface contact state on predicting the scuffing failure stage is further revealed.By comparing with the test,the correctness of the scuffing failure analysis model established in this paper is verified theoretically. |
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