APPLICATION OF WATER-AIR COOLING TECHNOLOGIES FOR HEAT TREATMENT OF BEARING RINGS

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.