Numerical investigation of influence of molten aluminum overheating on heat transfer in continuous combined casting and pressing

Abstract

The article presents the results of a numerical study of temperature-time dependences in continuous combined casting and pressing of the AK12 experimental aluminum alloy, which has a different overheating temperature, in the time interval from start-up to the moment of the unit reaching the stationary thermal regime. Calculations are carried out on the basis of a three-dimensional computer model of complex heat transfer in the unit of a new design equipped with a horizontal carousel crystallizer. Theoretical studies are conducted to determine the influence of superheating of poured aluminum melt on the processes of unsteady heat transfer. The influence of the nature of heat transfer in the transient thermal regime on the temperature field of the solidifying melt at different distances from the pour point is determined. It is shown that as the crystallizer heats up in the transition process, the asymmetry of the temperature field in the control section of metal increases near the pressing tool with the shift of the maximum temperature region to the crystallizer contac surface. It is found that the transition process duration when starting the unit in a cold state until it reaches a stationary thermal regime depends on the temperature of poured melt. The maximum limit of the overheating value is determined, above which poured metal, when implementing the technology of continuous combined casting and pressing, aluminum melt does not solidify in the crystallizer and forced cooling of unit elements must be arranged. The influence of melt overheating on the pattern of the temperature field along the crystallizer cross section over the entire period of the transient thermal process is estimated. Design measures to ensure rational temperature conditions of bearings during the unit operation are determined.