Analysis of Separation Conditions for Shrink Fitting System Used for Ceramics Conveying Rollers

Abstract

Steel conveying rollers used in hot rolling mills must be exchanged frequently at great cost because hot conveyed strips induce wear and deterioration on the surface of roller in short periods. In this study, new roller structure is considered which has a ceramics sleeve connected with two steel shafts at both ends by shrink fitting. Here, although the ceramics sleeve can be used for many years, the steel shaft sometimes has to be exchanged for reconstruction under corrosive action induced by water cooling system. Since the thermal expansion coefficient of steel is about five times larger than that of ceramics, it is necessary to investigate how to separate the shrink fitting system by heating outside of sleeve and cooling inside of the shaft. In this study, the finite element method is applied to analyze the separation mechanism by varying the geometrical and thermal conditions for the structure. Finally the most appropriate dimension and thermal conditions have been found, which may be useful for designing of new rollers.