Geometrical Optimization of the EHL Roller Face/Rib Contact for Energy Efficiency in Tapered Roller Bearings

Abstract

In the context of targeted improvements in energy efficiency, secondary rolling bearing contacts are gaining relevance. As such, the elastohydrodynamically lubricated (EHL) roller face/rib contact of tapered roller bearings significantly affects power losses. Consequently, this contribution aimed at numerical optimization of the pairing’s macro-geometric parameters. The latter were sampled by a statistical design of experiments (DoE) and the tribological behavior was predicted by means of EHL contact simulations. For each of the geometric pairings considered, a database was generated. Key target variables such as pressure, lubricant gap and friction were approximated by a meta-model of optimal prognosis (MOP) and optimization was carried out using an evolutionary algorithm (EA). It was shown that the tribological behavior was mainly determined by the basic geometric pairing and the radii while eccentricity was of subordinate role. Furthermore, there was a trade-off between high load carrying capacity and low frictional losses. Thereby, spherical or toroidal geometries on the roller end face featuring a large radius paired with a tapered rib geometry were found to be advantageous in terms of low friction. For larger lubricant film heights and load carrying capacity, spherical or toroidal roller on toroidal rib geometries with medium radii were favorable.

Application of Hertzian theory to torus on plane contacts

“…8 Because of their wide use in the automobile industry, the reduction of friction in tapered roller bearings is an established and active topic in tribological research. [9][10][11][12] The flange-roller end contact in a bearing is the tribologically critical one in tapered roller bearings due to the high degree of sliding. 13 Particularly at low speeds and high loads, the frictional torque of the bearing due to the flange-roller end contact dominates.…”

“…14,15 Compared to standard EHL calculations, which are often done for Hertzian contacts, the true geometry of the flange-roller end contact is more complicated. 3,16,11 For Hertzian contacts, the undeformed gap height can be adequately approximated by a quadratic function, see Equation 1. This is of great benefit because of the ease of implementation and computational efficiency.…”

“…For flange-roller end contacts, more complicated geometrical models are necessary. There have been two main strategies: One has been to use a simplifying assumption of an elliptical contact 17,6,13 and the other has been to model the geometry more accurately in various ways, 18–20,3,11 which complicates the calculation but has higher modeling accuracy.…”

Current Trends and Applications of Machine Learning in Tribology—A Review

“…To predict the class of cage motion, Schwarz et al applied decision trees as weak learners within an ensemble classification model based on AdaBoostM1 [72] to achieve good results. Furthermore, Wirsching et al [73] aimed at tailoring the roller face/rib contact in tapered roller bearings. Geometric parameters were sampled by a Latin hypercube sampling (LHS) and the tribological behavior was predicted by means of elastohydrodynamic lubrication (EHL) contact simulations.…”

Thermal elastohydrodynamic lubrication characteristics and optimisation of the ball-type tripod universal joint

“…In addition, the application of machine learning (ML) algorithms to predict the tribological behaviour of EHL has attracted attention from researchers. Wirsching et al (2021) used a meta-model of optimal prognosis (MOP) combined with an evolutionary algorithm (EA) to optimise the EHL of tapered roller bearings. Marian et al (2019a, 2019b) investigated the effect of micro-texture on EHL by ball-on-disk experiments and three-dimensional EHL simulation, and used MOP and EA to optimise the micro-texture parameters.…”