Application of Water-Air Cooling Technologies for Heat Treatment of Bearing Rings

Abstract

The paper presents the results of mathematical modeling and experimental researches executed during the development of the techno logy of differential water-air cooling of bearing rings made of 52100 (EN1.3505) steel produced by JSC “Vologda Bearing Plant”. Overlapping the mathematical model of temperature variation curves across the bearing cross-section on the thermokinetic diagram of the decomposition of supercooled austenite calculated according to the mathematical model developed by JSC VNIIMT has shown that a required microstructure of the heat-treated metal is achieved in a wide range of differentiated water-air cooling modes. Experimental studies of heat-strengthening of bearing rings by water-air jets were carried out on a specially assembled experimental industrial device with a cooling system equipped with mixers and collectors with flat-jet nozzles of the original design that ensure the stability of the torch and the uniformity of spraying the water-air mixture over a wide range of flow rates and water and air pressure. The thermal hardening of the rings carried out at various cooling regimes, followed by the determination of the mechanical properties and structural characteristics of the steel, has confirmed that the water-air cooling technology achieves the required structural and mechanical characteristics of the bearing rings and is a competitive, environmentally friendly alternative to the technology of volume quenching in oil tank.