| Abstract: | In this paper the solution of the unsteady, three-dimensional heat transfer in work rolls was derived by using Bessel functions and the δ-function and expressed by an infinite series. In this manner other problems of heat transfer in solid cylinders and hollow cylinders can also be calculated. The temperature profile of the work roll due to the distribution of the temperature in the axial direction can cause unregular pressure distribution between work roll and backup roll and can influence the quality of strip. Therefore, the thermal crowns must be considered at various moments during rolling. The thermal crown can be determined by using the FE-Method or others. The reason for the fire-cracking in the roll surface can be determined as the thermal shock load in the contact zone, in which the sharp compressive stresses lead to local plastic deformation. The local plastic deformations are followed by residual deformations. Therefore, residual tensile stresses occur in the cooling zone. On each revolution, the surface undergoes plastic strain in compression and in tension. The result is thermal fatigue. The fine network of cracks in the roll surface can result in a sharp stress concentration which is dangerous for the rolls loaded with a bending moment. The maximum tensile stresses due to the temperature distribution occur in the roll core, which usually do not lead to damages of the rolls. |
