# Analysis of the Influence of Segmented Rollers on Slab Bulge Deformation
## 5 Influences of Roller Spacing and Roller Diameter on Slab Bulge Deformation
### Results and Conclusions  
#### 5.2.1 Influences of Roller Spacing on Bulge Deformation  
Roller spacing was adjusted by changing the gap between the rollers. Under the condition of constant casting speed (1.5 m\(\cdot\)min\({}^{-1}\)), the bulge deformation was calculated with 350 and 400 mm as the roller spacings. The average values of the bulge deformation were compared with that of a 300-mm roller spacing. The diameter of the roller was 230 mm. The results of slab bulge deformation on the wide side, shown in Figure 10 and Table 6, were established by the simulation model with \begin{table}
\begin{tabular}{c c c c c} \hline \multirow{2}{*}{**Roller Spacing**} & **Rigid** & **Elastic** & **Two-Segment** & **Three-Segment** \\  & **Roller** & **Roller** & **Roller** & **Roller** \\ \cline{2-5}  & \multicolumn{4}{c}{**Roller Diameter**} \\ \hline \multirow{3}{*}{300 mm} & 230 mm & 230 mm & 230 mm & 230 mm \\  & 250 mm & 250 mm & 250 mm & 250 mm \\  & 270 mm & 270 mm & 270 mm & 270 mm \\ \hline
350 mm & 230 mm & 230 mm & 230 mm & 230 mm \\
400 mm & 230 mm & 230 mm & 230 mm & 230 mm \\ \hline \end{tabular}
\end{table} 
Table 5: Simulation parameters of bulging models. Figure 9: The vertical displacement of different casting rollers. different roller spacings. It could be concluded that the approximate distribution of the slab bulge deformation on the wide side would not change with a 50 mm increase of the roller spacing, and the improvement of the three-segment roller for bulge deformation was most obvious. However, the bulge deformation of the slab under the same continuous casting segmented roller increased greatly with the increase of the roller spacing. The maximum increment of bulging deformation was 67.1% under the rigid roller with the roller spacing changing from 300 to 350 mm. The maximum increment of bulge deformation under the elastic roller was 47.4%, with the roller spacing changing from 350 to 400 mm. The maximum increment of bulge deformation under the two-segment roller was 37.5%, with the roller spacing changing from 300 to 350 mm. The maximum increment of bulge deformation under the three-segment roller was 60.0%, with the roller spacing changing from 300 to 350 mm. The bulging increase was about the same for the rigid roller and the three-segment roller. This also proved that the effect of the three-segment roller was closest to that of the rigid roller on slab bulge deformation. The minimum increment was 32.9% under the elastic solid roller with the roller spacing changing from 300 to 350 mm. An analysis of variance (Table 6) showed that the value of variance ratio was 158.45 under different roller spacings, which was larger than the critical value of variance ratio (the critical value was 5.14). The value of variance ratio was 35.38 under different segmented rollers, which was larger than the critical value of variance ratio (the critical value was 4.76). This indicated that different roller spacings and segmented rollers all have a significant effect on slab bulge deformation. Generally, the slab bulge deformation on the wide and narrow sides increased with the increasing roller spacing. This was because the area of the slab between the two rollers increased with the increasing roller spacing. The effect of static pressure increased in the solidified shell, which indirectly reduced its stiffness. As a result, the value of slab bulge deformation became larger as the roller spacing increased. This indicated that roller spacing also played an important role in bulge deformation of the casting slab. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Roller Spacing**} & **Rigid** & **Elastic** & **Two-Segment** & **Three-Segment** \\  & **Roller** & **Roller** & **Roller** & **Roller** \\ \hline
300 mm & 0.82 mm & 1.43 mm & 1.28 mm & 0.90 mm \\
350 mm & 1.37 mm & 1.90 mm & 1.76 mm & 1.44 mm \\
400 mm & 1.93 mm & 2.80 mm & 2.38 mm & 1.96 mm \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Bulge deformation on the wide side with different roller spacings.