Interaction Analysis of the Twin-Roller Strip-Casting Process and the Implications for Process Control

Edwards, J.B.; Cavazos, Alberto

doi:10.1361/10599490523869

Cited by 7 publications

(10 citation statements)

References 14 publications

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“…high cross-coupling elements. The most critical of them was found to be the cross-coupling element from q i to F. The interaction ratios of column 2 are higher than 1 for all frequencies and it is higher at low pool level 14,15 . For low level operating conditions, it is assumed the only Y l changes, while F, Y k , and T remain constant.…”

Section: The Plantmentioning

confidence: 89%

“…As mentioned earlier, the 3 x 3 model derived originally 12 having three outputs: i) F, ii) Y l and iii) x g ; and three inputs: i) Ω, ii) q i and iii) spool valve displacement (d); was simplified 13 by assuming the gap to be constant, (gap dynamics are not given here, see Hargrave 13 and Cavazos 14 and Edwards and Cavazos 15 ). This implies that the diagonal gap controller is very tight and that its speed of response greatly exceeds that of the dynamics driven by q i , Ω and the shell-forming process.…”

Section: Model Of the Twin Roller Castermentioning

confidence: 99%

“…One of the conclusions was that the multivariable approach becomes crucial due to the high level of interactions. The results of a full multivariable analysis have been presented 14,15 . The controlled variables of the 2 x 2 model are roll separation force (F) and pool level (Y l ).…”

mentioning

confidence: 99%

“…The validation of the model in a real-life caster is not presented here 14,15 . However, the model used here was calibrated according to a pure static model which has been in use in the industrial site and has been experimentally validated.…”

mentioning

confidence: 99%

“…This model has been in use satisfactorily and it is considered to be a good approximation of the plant in steady state. Calibration details can be found in 15 . A realtime simulator based on the model derived and presented in this work was also built.…”

mentioning

confidence: 99%

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Force/Level Control of the Twin-Roller Strip Caster

Edwards

Cavazos

2005

Measurement and Control

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S teel plays an essential role in modern society. Steel applications range from the simplest tools to highly specialised devices. Such celebrated success of steel is due to its outstanding versatile characteristics, from high strength to electrical, from elasticity and malleability to high-quality surface finishing. On the other hand, steel offers an excellent compromise between performance and cost. No other material possesses such as wide working range and relatively low cost.From all the steel applications, those which involve flat profile geometry are probably the most relevant. This turns the flat steel processes into some of the most relevant industrial processes worldwide. Therefore, their study becomes of crucial importance in order to satisfy modern society demands.Continuous strip casting is a novel process to produce flat strip of steel and it offers industry the opportunity to reduce production cost, energy consumption, and the loss of material by partial or total elimination of subsequent shaping stages. The capital cost will also be reduced as a result of the installation of low-head machines and the elimination of roughing stands in strip mills 1, 2 . The need for highly responsive interactive control is a consequence of the reduction in storage capacity of the strip caster in comparison to the traditional processes. This process can also bring an improvement in uniformity quality and new properties to the final steel produced.The twin-roller strip casting process is suitable to cast directly thin strip of thickness between 1 mm and 5 mm, or even thinner 3 . However, successful implementation is very much dependent on the highly interactive processes of heat and fluid flow and, therefore, on the control of heat and flow extraction. The solidification rate has to be controlled to allow good mechanical properties of the final product and avoid surface cracking and faults in the structure of the solidified steel.Several works on control of twin-roller caster have been reported in the literature, but little attention has been given to the multivariable aspect of the process 4 -11 . In previous investigations within the Department of Automatic Control and Systems Engineering (ACSE) of the University of Sheffield 12, a 3 x 3 model of a real-life twin-roller strip caster, suitable for control analysis and design, has been derived. The process has been found to be highly interactive and non-linear with presence of unbreakable delayintegrator loops. Nonetheless, a linearised model of the process has been proposed. Such model was simplified to a 2 x 2 model on justified basis (strip thickness was discarded from the model, see Section 3) and a time domain (step response) multivariable analysis has been performed 13 . One of the conclusions was that the multivariable approach becomes crucial due to the high level of interactions. The results of a full multivariable analysis have been presented 14,15 . The controlled variables of the 2 x 2 model are roll separation force (F) and pool level (Y l ). The manipulat...

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Section: The Plantmentioning

confidence: 89%

Section: Model Of the Twin Roller Castermentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Force/Level Control of the Twin-Roller Strip Caster

Edwards

Cavazos

2005

Measurement and Control

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A Decoupling Control Model on Perturbation Method for Twin-Roll Casting Magnesium Alloy Sheet

Zhang

Zhao

et al. 2015

Journal of Materials Science & Technology

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A Nonlinear Dynamic Switched-Mode Model of Twin-Roll Steel Strip Casting

Browne

Chiu

Jain

2019

Journal of Dynamic Systems, Measurement, and Control

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During twin-roll steel strip casting, molten steel is poured onto the surface of two casting rolls where it solidifies to form a steel strip. The solidification process introduces a two-phase region of steel known as mushy steel which has a significant effect on the resulting quality of the manufactured steel strip. Therefore, an accurate model of the growth of mushy steel within the steel pool is imperative for ultimately improving strip quality. In this paper, we derive a reduced-order model of the twin-roll casting process that captures the dynamics of the mushy region of the steel pool and describes the effect that the casting roll speed and gap distance have on the solidification dynamics. We propose a switched-mode description that leverages a lumped parameter moving boundary approach, coupled with a thermal resistance network analogy, to model both the steel pool and roll dynamics. The integration of these models and simulation of the combined model are nontrivial and discussed in detail. The proposed reduced-order model accurately describes the dominant dynamics of the process while using approximately one-tenth of the number of states used in previously published models.

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Interaction Analysis of the Twin-Roller Strip-Casting Process and the Implications for Process Control

Cited by 7 publications

References 14 publications

Force/Level Control of the Twin-Roller Strip Caster

Force/Level Control of the Twin-Roller Strip Caster

A Decoupling Control Model on Perturbation Method for Twin-Roll Casting Magnesium Alloy Sheet

A Nonlinear Dynamic Switched-Mode Model of Twin-Roll Steel Strip Casting

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