Analysis of roll gap heat transfers in hot steel strip rolling through roll temperature sensors and heat transfer models

This paper presents an analysis of roll bite heat transfers during pilot hot steel strip rolling. Two types of temperature sensors (drilled and slot sensors) implemented near roll surface are used with heat transfer models to identify interfacial heat flux, roll surface temperature and Heat Transfer Coefficient HTCroll-bite in the roll bite. It is shown that: - the slot type sensor is more efficient than the drilled type sensor to capture correctly fast roll temperature changes and heat fluxes in the bite during hot rolling but its life's duration is shorter. - average HTCroll-bite is within the range 15-26 kW/m2/K: the higher the strip reduction (e.g. contact pressure) is, the higher the HTCroll-bite is. - scale thickness at strip surface tends to decrease heat transfers in the bite from strip to roll. - HTCroll-bite is not uniform along the roll-strip contact but seems proportional to contact pressure. - this non uniform HTCroll-bite along the contact could contribute to decrease thermal shock (so roll thermal fatigue) when the work roll enters the roll bite, in comparison to a uniform HTCroll-bite. - Heat transfer in the roll bite is mainly controlled by heat conduction due to the huge roll-strip temperature difference, while heat dissipated by friction at roll-strip interface seems negligible on these heat transfers.