A Modified Wear Model Considering Contact Temperature for Spur Gears in Mixed Elastohydrodynamic Lubrication
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ORIGINAL PAPER
A Modified Wear Model Considering Contact Temperature for Spur Gears in Mixed Elastohydrodynamic Lubrication Changjiang Zhou1 · Mingcai Xing1 · Bo Hu1,2 · Zhaoyao Shi3 Received: 16 July 2020 / Accepted: 11 October 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract In this study, a modified wear model considering contact temperature for spur gears in mixed elastohydrodynamic lubrication (EHL) is proposed. The contact temperature consists of bulk temperature and flash temperature. The bulk temperature is determined by the thermal network model, whereas the flash temperature is estimated through the published method. The bulk temperature, which was rarely included in the previous works, substantially has a considerable influence on the tooth wear in mixed EHL. It is also found that the lower contact temperature contributes to the reduction of gear wear depth. Furthermore, the effects of gear basic geometrical parameter and operating parameter on wear depth are investigated. The results show that the wear depth decreases with the increased tooth width, module, pressure angle and rotational velocity but increases with the surface roughness and torque. It indicates that wear resistance of tooth surfaces can be enhanced by optimising the design parameters of gear drives. Graphic Abstract
Keywords Wear model · Contact temperature · Bulk temperature · Mixed EHL · Spur gears Extended author information available on the last page of the article
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List of Symbols B Tooth width (mm) b Half contact width (mm) ϲ Specific heat coefficient (J/(kg·K)) Ea Adsorption heat of lubricant (J/mol) Eeq Comprehensive elasticity modulus (Pa) Fn Normal meshing force (N) fc Frictional coefficient of asperity contact G Dimensionless elasticity modulus H Surface hardness (GPa) Hc Dimensionless central film thickness Hmin Dimensionless minimum film thickness hv Convective heat transfer coefficient (W/(m2 K)) K Dimensionless wear coefficient k0 Dimensional wear coefficient (m2/N) La Asperity contact ratio (%) ni Rotational speed (rpm) Pei Peclet coefficients p Contact pressure (Pa) pa Asperity contact pressure (Pa) q Heat flux (W/m2) R Curvature radius (mm) Ra Surface roughness (μm) Rg Molar gas constant (J/mol) [R] Thermal resistance matrix Se Area of convective heat transfer (mm2) Shj Area of heat conduction along tooth thickness (mm2) Smi Area of involute tooth surface (mm2) Stj Area of heat conduction along tooth height (mm2) s Relative sliding distance (mm) [T] Temperature matrix Ta Ambient temperature (K) TB Bulk temperature (K) Ts Contact temperature (K) t0 Basic time of molecular vibration (s) U Dimensionless rolling speed ui Tangential velocity (mm/s) ur Rolling speed (mm/s) us Relative sliding speed (mm/s) V Dimensionless surface hardness V′ Wear volume (mm3) W Dimensionless load Wa Normal load (N) X Diameter of the lubricant molecule (mm) [Ф] Heat flow matrix ΔT Flash temperature (K) αc Press
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