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Loopers

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Subject-Keyword: Loopers

Type of item: Journal Article Draft-Submitted

Language: English

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Description: Poor control of hot strip mill loopers degrades strip width and gauge, and may even lead to mill breakdowns due to instability. In this study, dynamics of the looper-strip system and the control challenges it poses are discussed, and covariance control theory is applied to variance control design for loopers. Since looper disturbances have a deterministic nature, and their accurate modelling is a challenge that is not easily addressed, the problem represents a case in which a variance controller has to be designed without an explicit disturbance model. Control performance is assessed on a full-stand, nonlinear high fidelity finishing mill simulator, and comparisons to a conventional control system are provided.

Date created: 2008

DOI: doi:10.7939-R3696ZZ83

License information: Creative Commons Attribution-Non-Commercial 3.0 Unported

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Author: Yildiz, S.K.

Source: https://era.library.ualberta.ca/


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Dynamics and Variance Control of Hot Mill Loopers Sansal K.
Yildiz, Biao Huang ∗ , J.
Fraser Forbes Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta, Canada T6G 2G6 Abstract Poor control of hot strip mill loopers degrades strip width and gauge, and may even lead to mill breakdowns due to instability.
In this study, dynamics of the looperstrip system and the control challenges it poses are discussed, and covariance control theory is applied to variance control design for loopers.
Since looper disturbances have a deterministic nature, and their accurate modelling is a challenge that is not easily addressed, the problem represents a case in which a variance controller has to be designed without an explicit disturbance model.
Control performance is assessed on a full-stand, nonlinear high fidelity finishing mill simulator, and comparisons to a conventional control system are provided. Key words: Loopers, Covariance control, Variance control, Hot strip mill, Hot rolling 1 Introduction A finishing mill produces thin sheet from hot steel bars by successively reducing the gauge using 5 to 7 sets of rolls, each called a mill stand.
The finishing mill is part of a hot strip mill, of which a typical layout is given in Figure 1. Those units of the hot mill located before the finishing mill are responsible for reheating the cast slab, effecting the major gauge reduction (roughing), and finally transferring the workpiece (now called a transfer bar) to the finishing mill.
After the finishing, the strip is cooled and coiled. It is the finishing mill where a smaller but more precise gauge reduction is carried out.
The strip emerging from a finishing mill can be as thin as 1.5 ∗ Corresponding author. Email address: biao.huang@ualberta.ca (Biao Huang ). Preprint submitted to Control Engineering Practice 7 April 2007 Water coolant headers Shear Transfer table Reheat furnaces Runout table Finishing mill Roughing stand Coiler Fi...





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