Rolling back-up rolls require high fracture toughness, particularly in the shaft portion, and high-hardness in the sleeve portion. The rolls are classified into two types; one is an integrated type and the other is a shrink-fitted type consisting of a sleeve and a shaft. The shrink-fitted roll has several advantages, for example, suitable materials can be chosen and the shaft can be reused by replacing the damaged sleeve. However, during use if the residual permanent deflection occurs, the roll cannot be used anymore. In this paper, an elastic-contact finite element method FEM analysis is performed to explain the residual permanent deflection mechanism. It is found that the quasi-equilibrium stress zone with the residual displacement causes the permanent slippage in the axial direction. In a similar way, the interface creep in the circumferential direction can be also explained from the quasi-equilibrium stress zone with the residual displacement.

Several ceramic rolls can be used efficiently to produce high quality zinc coated steel sheet used for automobiles. Those ceramics rolls may provide a longer life and reduce the cost for the maintenance because of its large heat resistance and large wear resistance. One example may be seen in sink rolls used in molten zinc bath to manufacture zinc coated steel sheet. Since the rolls are subjected to large thermal stress and mechanical loading, care should be taken for the risk of fracture due to the ceramic brittleness. Moreover, since the sleeve and shafts can be connected only by using small shrink fitting ratio, another failure risk should be considered for the separation of those components [25, 26]. In this paper, therefore, the mechanical and thermal stress and separation condition will be investigated considering the separation of the connected portion. Here, by using the finite volume method the heat transfer coefficient is discussed and by using the finite element method the thermal stress is considered.

The bimetallic work rolls are widely used in the roughing stands of hot rolling stand mills. The rolls are classified into two types: one is a single-solid type, and the other is a shrink-fitted construction type consisting of a sleeve and a shaft. Regarding the assembled rolls consisting of a sleeve and a shaft, the interfacial creep phenomenon can be seen between the shaft and the shrink-fitted sleeve. This interfacial creep phenomenon causes the relative displacement on the interface between the sleeve and the shaft. Although to clarify this creep mechanism is important issues, experimental simulation is very difficult to be conducted. In this paper, the interfacial creep phenomenon is realized by using the elastic finite element method (FEM) analysis. It is found that the interface creep can be regarded as the accumulation of the relative circumferential displacement on the interface of the sleeve and the shaft.