Improvement of prediction model for work roll thermal contour in hot strip mill

Abstract

Though high accuracy of the thermal contour was obtained while adopting finite element method, it could not meet the real-time requirement. One-dimensional finite difference method could realize real-time control in the case of neglecting both the circumferential and radical heat exchange, but the over-simplified modes resulted in poor accuracy. And two-dimensional full explicit difference was also limited in practical application since its time step was restricted to keep the model stable. Consequently, a new method of alternating direction finite difference was introduced and discussed in the model’s stability, calculating speed and precision. Specific work roll after one real rolling unit was researched, The result shows that error of temperature on work roll surface between measured and calculated values is within 5 °C. The influence of rolling rhythm and strip width on thermal crown was also studied. The conclusion is verified theoretically and practically that it can maintain absolutely stable and meet the online requirement.

Keywords

hot rolling / finite element / finite difference / work roll / thermal contour

References

[1] GinzburgV. B.. Application of coolflex model for analysis of work roll thermal conditions in hot strip mills [J]. Iron and Steel Engineer, 1997, 11: 42

[2] GinzburgV. B., GiustoD.. Roll thermal crown (RTC) control system [J]. MPT Metallurgical Plant and Technology International, 1994, 17(4): 80-81

[3] ZhangX.-l., ZhangJ., WeiG.-c., MaS.-hua.. Study on work roll temperature field and thermal profile in hot strip mills [J]. Metallurgical Equipment, 2002, 6(1): 133-136

[4] WangR.-z., HeA.-r., YangQuan.. Thermal contour model of work rolls in hot wide strip mills [J]. Journal of University of Science and Technology Beijing, 2004, 26(6): 654-657

[5] WangX.-d., YangQ., HeA.-r., WangR.-zhong.. Comprehensive contour prediction model of work roll used in online strip shape control model during hot rolling [J]. Ironmaking and steelmaking, 2007, 34(4): 303-311

[6] PanjkovicV., FraserG., YuenD.. Applications of the crown and shape model in blue scope steel’s western por hot strip mill [J]. Iron and Steel Technology, 2004, 1(10): 98-107

[7] CamposA. M., GarciD. F., AbajoN.. Real-time rule based control of the thermal crown of work rolls installed in hot strip mills [J]. IEEE Transactions on Industry Applications, 2004, 40(2): 642-649

[8] GuoZ.-f., LiC.-s., XuJ.-z., LiuX.-hua.. Analysis of temperature field and thermal crown of roll during hot rolling by simplified FEM [J]. Journal of Iron and Steel Research International, 2006, 13(6): 27-30

[9] STEVENS P G. Increasing work-roll life by improved rolling practice [J]. J Iron and Steel Inst, 1971(1): 1–6.

[10] TsengA. A., TongS. X., ChenT. C.. Thermal expansion and crown evaluations in rolling processes [J]. Material and Design, 1996, 1(4): 193-204

[11] TopnoR., PrakashK., JhaS. K.. Different colling of hot rolled angles to reduce thermal camber [J]. Steel Times International, 2003, 27(4): 18-20

[12] ColasR.. Modeling heat transfer during hot rolling of steel strip model [J]. Simul Mater Sci Eng, 1995, 3(4): 437-453

[13] PlloneG. T.. Transient temperature distribution in work rolls during hot rolling of sheet strip [J]. Iron Steel Eng, 1983, 5(12): 21-24

[14] YuenW. Y. D.. Research on the steady-state temperature distribution in a rotating cylinder subject to heating and cooling over its surface [J]. Trans ASME, 1984, 106(8): 578-583

[15] SumiH.. A numerical model and control of plate crown in the hot strip or plate rolling [J]. Advanced Technology of Plasticity, 1984, 1(2): 1360-1365

[16] HogsheadT. H.Temperature distributions in the rolling of metal strip [D], 1988, Pennsylvania, Camegie Mellon University