| The rapid development of new energy vehicles,high-precision industrial robots and high-speed rail transportation has increased the demand for high-performance gear transmission devices.Wear is one of the most direct causes of the damage of the tooth surface integrity,which leads to the vibration,noise and even failure of the gear system.Tooth surface wear is a dynamic accumulation of tooth profile material damage and removal process,which exists the whole service cycle of the gear transmission system.Mild tooth surface wear will change the meshing characteristics of gear pair,reduce the precision of transmission system and increase transmission error.Excessive tooth surface wear will cause vibration and noise,increas e the dynamic load of gear pair,and accelerate the occurrence of other failure forms,such as pitting and tooth breakage.Therefore,in-depth study of tooth surface wear characteristics of high-performance gears can provide theoretical basis for vibration and noise reduction and tooth surface failure analysis of gear system,and it is also an inevitable demand for the development of gear transmission system to the direction of high power density,high precision and lightweight.It is crucial to the stability and reliability of equipment.In this work,based on Archard’s adhesive wear theory and gear mesh theory,a general sliding distance model and a tooth surface contact pressure model were proposed.The wear models of standard and profile modified gears which including geometry and pressure updates were established.Then,the tooth wear models considering the lubrication and dynamic load were studied,and the influence of modification parameters on gear wear were analysed.The main research contents and conclusions are as follows:(1)A calculation method of tooth adhesive wear was proposed based on general sliding distance model.Based on elastic half-space theory,a general calculation model of contact stiffness between elastomers was established,which was applied to the calculation of time-varying meshing stiffness of gear pairs,and the load sharing factor between teeth was obtained.Then,the contact pressure between gear surfaces was established based on meshing principle and Hertz contact theory.According to the single point observation method,a general sliding distance model of mating tooth surfaces was proposed,and combined with Archard’s adhesive wear formula,a wear depth calculation model of tooth surface was established.The correctness of the proposed wear calculation model was verified by comparing with the results of tooth surface wear depth in the published literature.The calculation model of tooth surface wear was extended to helical gear pair,and the tooth surface wear distribution of helical gear was studied.The proposed general sliding distance model has a wide range of application and can be applied to other non-Hertz contact friction interfaces.(2)A tooth adhesive wear model was proposed considering geometry and pressure updates.The line contact problem was equivalent to a linear complement problem,and the conjugate gradient method was used to solve the contact pressure,which was verified by comparison with Hertz contact model and finite element contact model.Combined with the general sliding distance model and Archard’s wear formula,the wear model of line contact friction pair was established and verified by the wear test of ring-block pair.The line contact pressure model and wear model were extended to the gear drive,and the tooth surface wear was regarded as tooth profile deviation.Then,a calculation model of tooth surface wear depth considering geometry and pressure updates was established,which was verified by gear wear test,and the evolution law of tooth wear depth was analyzed.The result of proposed contact pressure model is more accurate and efficient than this of FE model.The line contact wear model and tooth surface wear model are in good agreement with the experimental results.(3)A wear prediction method for profile modified gears was presented and the influence of modification parameters on tooth surface wear were investigated.According to the principle of generating and tooth profile modification of gear,the geometric model of gear tip relief was established.The tooth profile error of profile modified gear pair along the line of action was derived and the calculation model of load sharing factor between modified gear pair teeth was established.Combined with the modified tooth profile equation,line contact pressure model and gear meshing theory,the contact pressure model of modified gear pair was established,and compared with the finite element model.The influence of tooth profile modification parameters on load sharing factor between teeth and tooth surface contact pressure was studied.Combined with the calculation method of tooth surface wear considering geometry and pressure updates,the calculation model of tooth surface wear of profile modified spur gear pair was established.The evolution law of tooth surface wear depth of tooth profile modification gear was analyzed,and the influence of tooth profile modification parameters on tooth surface wear was discussed.The unsmooth transition of tooth profile near the starting point of modification will cause a large contact pressure mutation phenomenon.Moderate tip relief is helpful to reduce the contact pressure at the engage-in and engage-out positions and the pressure mutation at the alternate positions of single-tooth contact and double-teeth contact,while excessive tip modification will reduce the bearing capacity of gear pair.(4)An adhesive wear calculation model for gears in mixed elastohydrodynamic lubrication(EHL)was proposed and the influence of rough surface and modification parameters on surface wear were studied.Based on the load sharing theory under mixed EHL,the line contact mixed EHL model was established by combining the mean Reynolds equation and ZMC rough surface cont act model.The results were compared with the oil film pressure and thickness in the published literature,and the asperity load ratio was obtained.Combined with the fractional film defect and the Archard’s adhesive wear model,the volume wear rate model of mixed EHL was established and compared with the experimental results.The volumetric wear rate model was extended to gear pairs,and the calculation model of tooth surface wear depth under mixed elastohydrodynamic lubrication was established.The evolut ion law of tooth surface wear depth under mixed EHL and the difference between mixed EHL and dry contact were analyzed,and the effects of surface roughness and tooth profile modification parameters on tooth surface wear were studied.The wear depth of the tooth surface under EHL was small.The key to improve the wear resistance of the tooth surface was to use lubricant reasonably and reduce the roughness of the tooth surface.(5)A calculation method of tooth surface adhesi ve wear was proposed under dynamic load.Considering the elastic deformation of the shaft,the dynamic model of the elastic shaft was established based on FE theory and Timoshenko beam theory.Coupled with the elastic shaft model,the gear rotor model and contact model,the support bearing model,the elastic dynamic of the gear-rotor-bearing system was established,and the dynamic meshing force of the tooth surface was solved based on Newmark method.Combined with the dynamic wear coefficient model,the calculation model of tooth surface wear depth under dynamic load was established.Considering the tooth surface wear depth as the tooth profile error,the elastic dynamic model of the gear-rotor-bearing system with tooth surface wear was established.The evolution law of tooth surface adhesi ve wear under dynamic load,and the difference between tooth surface wear under dynamic load and quasi-static load were analyzed.The influence of rotation speed and tooth profile modification parameters on tooth wear was studied.The tooth surface wear depth under dynamic load fluctuates around the tooth surface wear depth under quasi-static load,and the maximum tooth surface wear depth and its amplitude increase with the increase of rotational speed.Tip relief can effectively reduce the tooth surface we ar depth at the engage-in and engage-out positions of the gear pair under dynamic load.In conclusion,this work aiming at the quantitative calculation of gear tooth surface wear.Based on Archard’s wear formula,combined with elasticity theory,gear meshing theory,mixed elastohydrodynamic lubrication theory and rotor dynamics theory,the calculation model of tooth surface wear depth of gear pair under different working conditions was established.The influence of gear design parameters and modification parameters on tooth surface wear depth was analyzed,which provides a theoretical basis for anti-wear design and vibration and noise reduction analysis of gear transmission system. |
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