THERMAL EHL ANALYSIS OF CYLINDRICAL ROLLER UNDER HEAVY LOAD

摘要

Full numerical solutions to finite line contact elastohydrodynamic lubrication (EHL) problems are presented. Using the multi-level multi-integration (MLMI) method and some dedicated numerical techniques, convergence has been obtained for severe working conditions (contact pressure can reach 1.0 GPa and the length-width ratio of contact area are over 100 for a roller contact). The well known experiments of Wymer and Cameron have been quantitatively simulated and satisfactory agreement has been obtained. A modification coefficient of the Lundberg profile, δ, has been defined and it has been found that in EHL conditions the crowning value may be several times larger than that in the dry contact state. Both pressure and film thickness distributions should be considered in the EHL state and there is an optimum range of crowning value, expressed by δ as [δ_1, δ_2], for particular operating conditions. As load increases δ_1 increases and δ_2 is almost unchanged, and a smaller crowning value is needed for higher velocities. However, the effect of velocity on the crowning value is small compared with that of the load.