Thermovision measurements of rolling bearings

Abstract

In rolling bearings diagnostics, apart from the most commonly used vibration and noise measurements, temperature measurements are also taken. Further, the most common measurement method of bearings temperature is contact measurement of the temperature of the stationary outer ring of the bearing. However, simulation research proves that the most important thermal phenomena in the bearings occur in the contact area of the rolling elements and raceways. Temperature measurement of the moving rolling elements and the cages in bearings is possible only by non-contact methods. This paper describes the methodology of taking measurements during the diagnosis of rolling bearings using a thermal imaging camera. A procedure for parameterization of thermograms has been proposed, which enables the temperature of bearing elements to be determined. The key for this purpose was the emissivity coefficient ε and the temperature correction, related to the variable local values of ε of the tested bearing elements. The results of non-contact temperature measurements and the correction were verified by the contact method. The research included measurements of thermal processes taking place in new, undamaged tapered roller bearings. The tests were carried out on CBK 171 (SKF 63174) bearings. The selection of tapered roller bearings was dictated by the possibility of thermovision measurements of all the bearing elements.