New temper rolling model for advanced evaluation of rollability
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Proceedings 3rd International Steel Conference on New Developments in Metallurgical Process Technologies (METEC InSteelCon 2007)
Usual mathematical models for cold rolling cannot be used in temper rolling conditions, as high work roll flattening, high macroscopic friction between work roll and strip due to textured work rolls, significant elasto plastic strip behavior and the potential appearing of “contained plastic flow” make the situation much more complicated.
Temper rolling models are frequently based on a strip segment model using a circular arc work roll deformation, where the deformed work roll contour is approximated by an enlarged work roll Radius R’, which is calculated by the use of Hitchcock's formula (R’ > R, R denoting the undeformed work roll radius). The prediction of temper rollability by such models is very doubtful due to the fact that the temper rolling limits are generally far beyond the validity area of Hitchcock's formula. Consequently, temper rollability may at the best be roughly estimated by limiting the ratio of R’/R.
Siemens VAI’s new Triple-A temper rolling model is presented applying a non-circular arc theory for the calculation of elastic work roll flattening. A big advantage of Triple-A is that the calculation can be continued until and beyond the rollability limits, providing a unique tool for dimensioning temper rolling mills.
The underlying theory for the advanced evaluation of rollability as well as some simulation results for calculated rollability limits will be presented and discussed.
The underlying rate-dependent elasto plastic model of the strip allows the appearance of several subsequent elastic and plastic zones. The consequence is that the case of “contained plastic flow” will appear automatically without any additional simplifying assumptions.
The simulation results were compared with results from FEM calculations as well as verified and calibrated against practical data from an industrial temper rolling mill yielding excellent agreement between measured and predicted rolling forces.
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Notiz zur Publikation:
Temper rolling model, Non circular arc, Evaluation of rollability, Temper rollability, Rollability limits, Theoretical rollability, Practical rollability, Triple A model