The contact characteristics of the rough tooth surface during the meshing process are significantly affected by the lubrication state.The coupling effect of tooth surface roughness and lubrication on meshing character...The contact characteristics of the rough tooth surface during the meshing process are significantly affected by the lubrication state.The coupling effect of tooth surface roughness and lubrication on meshing characteristics of planetary gear is studied.An improved three-dimensional(3 D)anisotropic tooth surface roughness fractal model is proposed based on the experimental parameters.Considering asperity contact and elastohydrodynamic lubrication(EHL),the contact load and flexibility deformation of the tooth surface are derived,and the deformation compatibility equation of the 3 D loaded tooth contact analysis(3 D-LTCA)method is improved.The asperity of the tooth surface changes the system from EHL to mixed lubrication and reduces the stiffness of the oil film.Compared with the sun planet gear,the asperity has a greater effect on the meshing characteristics of the ring-planet gear.Compared with the proposed method,the comprehensive stiffness obtained by the traditional calculation method considering the lubrication effect is smaller,especially for the ring-planet gear.Compared with roughness,speed and viscosity,the meshing characteristics of planetary gears are most sensitive to torque.展开更多
In order to effectively improve meshing performance of spiral bevel and hypoid gears generated by the duplex helical method, the effects of straight lined and circular cutting edges profile on meshing and contact of s...In order to effectively improve meshing performance of spiral bevel and hypoid gears generated by the duplex helical method, the effects of straight lined and circular cutting edges profile on meshing and contact of spiral bevel and hypoid gears were investigated analytically. Firstly, a mathematical model of spiral bevel and hypoid gears with circular blade profile was established according to the cutting characteristics of the duplex helical method. Based on a hypoid gear drive, the tooth bearings and the functions of transmission errors of four design cases were analyzed respectively by the use of the tooth contact analysis(TCA), and the contact stresses of the four design cases were analyzed and compared using simulation software. Finally, the curvature radius of the circular profile blade was optimized. The results show that the contact stresses are availably reduced, and the areas of edge contact and severe contact stresses can be avoided by selecting appropriate circular blade profile. In addition, the convex and concave sides are separately modified by the use of different curvature radii of inside and outside blades, which can increase the flexibility of the duplex helical method.展开更多
Wear and scuffing failures often occur in marine transmission gears due to high friction and flash temperature at the interface between the meshing-teeth.In this paper,a numerical solution procedure was developed for ...Wear and scuffing failures often occur in marine transmission gears due to high friction and flash temperature at the interface between the meshing-teeth.In this paper,a numerical solution procedure was developed for the predictions of transient friction and flash temperature in the marine timing gears during one meshing circle based on the 3D line contact mixed lubrication simulation,which had been verified by comparing the flash temperature with those from Blok’s theory.The effect of machined surface roughness on the mixed lubrication characteristics is studied.The obtained results for several typical gear pairs indicate that gear pair 4-6 exhibits the largest friction and the highest interfacial temperature increase due to severe rough surface asperity contacts,while the polished gear surfaces yield the smallest friction and the lowest interfacial temperature.In addition,the influences of the operating conditions and the gear design parameters on the friction-temperature behaviors are discussed.It is observed that the conditions of heavy load and low rotational velocity usually lead to significantly increased friction and temperature.In the meantime,by optimizing the gear design parameters,such as the modulus and the pressure angle,the performance of interfacial friction and temperature can be significantly improved.展开更多
A roller rack pinion(RRP)system,which consists of a rack-bar and a cam pinion,transforms a rotation motion into linear motion.The rack-bar has a series of roller train and meshes with the cam pinion.First,the exact to...A roller rack pinion(RRP)system,which consists of a rack-bar and a cam pinion,transforms a rotation motion into linear motion.The rack-bar has a series of roller train and meshes with the cam pinion.First,the exact tooth profile of the cam pinion and the non-undercut condition to satisfy the required performance have been proposed with the introduction of the profile shift coefficient.Then,the load stress factors are investigated under the variation of the shape design parameters to predict the gear surface fatigue limit which is strongly related to the gear noise and vibration at the contact patch.The results show that the pitting life can be extended significantly with the increase of the profile shift coefficient.展开更多
基金Project(2024A1515240020)supported by the Guangdong Basic and Applied Basic Research Foundation,China。
文摘The contact characteristics of the rough tooth surface during the meshing process are significantly affected by the lubrication state.The coupling effect of tooth surface roughness and lubrication on meshing characteristics of planetary gear is studied.An improved three-dimensional(3 D)anisotropic tooth surface roughness fractal model is proposed based on the experimental parameters.Considering asperity contact and elastohydrodynamic lubrication(EHL),the contact load and flexibility deformation of the tooth surface are derived,and the deformation compatibility equation of the 3 D loaded tooth contact analysis(3 D-LTCA)method is improved.The asperity of the tooth surface changes the system from EHL to mixed lubrication and reduces the stiffness of the oil film.Compared with the sun planet gear,the asperity has a greater effect on the meshing characteristics of the ring-planet gear.Compared with the proposed method,the comprehensive stiffness obtained by the traditional calculation method considering the lubrication effect is smaller,especially for the ring-planet gear.Compared with roughness,speed and viscosity,the meshing characteristics of planetary gears are most sensitive to torque.
基金Project(2011CB706800-G)supported by the National Basic Research Program of ChinaProject(51375159)supported by the National Natural Science Foundation of China+1 种基金Project(20120162110004)supported by the Postdoctoral Science Foundation of ChinaProject(2015JJ5020)supported by the Science Foundation of Hunan Province,China
文摘In order to effectively improve meshing performance of spiral bevel and hypoid gears generated by the duplex helical method, the effects of straight lined and circular cutting edges profile on meshing and contact of spiral bevel and hypoid gears were investigated analytically. Firstly, a mathematical model of spiral bevel and hypoid gears with circular blade profile was established according to the cutting characteristics of the duplex helical method. Based on a hypoid gear drive, the tooth bearings and the functions of transmission errors of four design cases were analyzed respectively by the use of the tooth contact analysis(TCA), and the contact stresses of the four design cases were analyzed and compared using simulation software. Finally, the curvature radius of the circular profile blade was optimized. The results show that the contact stresses are availably reduced, and the areas of edge contact and severe contact stresses can be avoided by selecting appropriate circular blade profile. In addition, the convex and concave sides are separately modified by the use of different curvature radii of inside and outside blades, which can increase the flexibility of the duplex helical method.
基金Project(51905118)supported by the National Natural Science Foundation of ChinaProject(3072020CF0306)supported by the Fundamental Research Funds for the Central Universities,China。
文摘Wear and scuffing failures often occur in marine transmission gears due to high friction and flash temperature at the interface between the meshing-teeth.In this paper,a numerical solution procedure was developed for the predictions of transient friction and flash temperature in the marine timing gears during one meshing circle based on the 3D line contact mixed lubrication simulation,which had been verified by comparing the flash temperature with those from Blok’s theory.The effect of machined surface roughness on the mixed lubrication characteristics is studied.The obtained results for several typical gear pairs indicate that gear pair 4-6 exhibits the largest friction and the highest interfacial temperature increase due to severe rough surface asperity contacts,while the polished gear surfaces yield the smallest friction and the lowest interfacial temperature.In addition,the influences of the operating conditions and the gear design parameters on the friction-temperature behaviors are discussed.It is observed that the conditions of heavy load and low rotational velocity usually lead to significantly increased friction and temperature.In the meantime,by optimizing the gear design parameters,such as the modulus and the pressure angle,the performance of interfacial friction and temperature can be significantly improved.
基金Research financially supported by Changwon National University in 2011-2012,Korea
文摘A roller rack pinion(RRP)system,which consists of a rack-bar and a cam pinion,transforms a rotation motion into linear motion.The rack-bar has a series of roller train and meshes with the cam pinion.First,the exact tooth profile of the cam pinion and the non-undercut condition to satisfy the required performance have been proposed with the introduction of the profile shift coefficient.Then,the load stress factors are investigated under the variation of the shape design parameters to predict the gear surface fatigue limit which is strongly related to the gear noise and vibration at the contact patch.The results show that the pitting life can be extended significantly with the increase of the profile shift coefficient.
