An, FE-based, off-line model is presented for the precise prediction of roll thermal profile. The validity of the model is demonstrated through comparison with measurements. Also demonstrated is its capability of reflecting the effect of diverse process variables.KEY WORDS: finite element method; off-line model; roll thermal profile.roll) and strip (JS-SS400) and other process variables selected for process simulation were shown in Table 1. The thermal and mechanical boundary conditions and the FE meshes were illustrated in Fig. 2 and in Fig. 3, respectively.
Surface Temperatures of the Roll and StripInvestigated was the transient thermal behavior of the roll-strip system during a very short period of time after initiation of rolling of the first strip. The roll initial temperature, as well as the initial temperature of the strip in the bite region before initiation of rolling, was assumed to be 20°C. It was found that in 0.4 sec after initiation of rolling, the strip surface temperatures at the roll-strip interface as well as the core temperatures of the strip in the bite region almost reached the steady-state temperatures, as shown in Fig. 4. Considering that normally the rolling time would be much longer than 0.4 sec, the present result indicated that ISIJ International, Vol. 40 (2000), No. 8
795© 2000 ISIJ the transient strip temperature distributions may be approximated by the steady-state temperature distributions. It was seen from Fig. 5(a) that the same conclusion may be drawn for the surface temperatures of the roll at the roll-strip interface. However, except at the roll-strip interface, the transient roll surface temperatures were far from reaching the steady-state, as shown in Fig. 5(b).
Roll Main Body TemperaturesIllustrated in Fig. 6 was the gradual increase of the roll main body temperatures as rolling proceeded. The temperature distributions in the roll was remarkably axi-symmetric, except in a thin, circular layer encompassing the roll main body where the temperature gradient in the radial direction was very large, especially at the roll-strip interface. The thickness of the thin layer was found to be less than 5 mm or 1.2 % of the roll radius, indicating that its effect on overall roll thermal expansion could be neglected. Also revealed was that the roll main body temperatures, predicted at the completion of rolling of the fifth strip, were only a fraction of the steady-state roll main body temperatures (which were about 65°C), which may be attributed to periodic roll idling.
An Off-line Model for the Prediction of RollThermal Profile
Prediction of Roll Main Body TemperaturesOn the basis of the characteristics of the transient thermal behavior revealed by process simulation with the integrated FE process model, a simplified approach was developed for the prediction of roll main body temperatures, ISIJ International, Vol. 40 (2000), No. 8 which was described in the following:At any moment during rolling, net heat flux coming into the roll through the entire roll arc at a given plane perpendicu...