Optical interferometric EHL oil film measurement in finite line contacts

A test apparatus was developed to measure the elastohydrodynamic lubrication (EHL) oil film thickness and film shape for finite line contacts based on the principle of optical interferometry, which could be used to study the oil film forming mechanism of roller bearings on pure rolling working conditions. The key problem of the experiment is that the high quality interferograms could be caught continuously, that is depended on the dynamic optical interferometric method, the smooth properties of driven and loading system of the test rig. A local very flexible hydrostatic thrust bearing loading system and the coating layers techniques was used successfully to reduce the tensile stress in glass disk, and overcome the unstable load caused by driving system due to the inevitable error in the manufacture and assemble of the apparatus, and increase the refractive index between the glass and oil interface. The results of actually measurement shown the variation of oil film shape and film thickness in the contact area could be observed intuitively and recorded accurately by this test apparatus. By comparing results of calculation and experiment, it was found the agreements between them are quite coincident with each other.