Thermal model and optimal time scheduling of hot rolling

Project focus

• Modeling of the temperature evolution of plates during hot rolling
• Observer design based on pyrometer measurements
• Optimization of processing times

Description

In the production of heavy plates, it is important to know the current temperature of the product and to adjust it by adaptation of process times. The temperature evolution is decisive for the production process because many mechanical properties of the product are temperature-dependent, e.g., the yield stress. Furthermore, the temperature evolution also influences the microstructure and thus other important material properties of the final product.

Heavy plate rolling mill, Copyright: Dillinger Hüttenwerke AG.

The production steps of hot rolling influence the plate temperature in different ways: On the one hand, the plate temperature decreases due to air cooling or the contact with water and the work rolls. On the other hand, the deformation in the roll passes leads to a rise of the plate temperature. The thermal model has to capture these different aspects.

Scaled slab on the roller table, © Dillinger Hüttenwerke AG.

By means of the thermal model, the waiting periods that are necessary for the plates to reach their desired rolling temperatures in each pass can be calculated with higher accuracy. Consequently, not only a higher quality of the final product can be achieved, but the production process can also be organized more efficiently because the waiting times can be planned more precisely.

To cope with model inaccuracies or unexpected disturbances, a model-based observer corrects the model predictions. The observer uses measurements of the product surface temperature. As contact measurements are infeasible due to the moving surfaces and the difficult measurement conditions, the surface temperature has to be measured by pyrometers. However, these pyrometer measurements are only feasible at discrete points outside the mill stands. The scarcity of measurements is an additional challenge for the observer design.

Selected Publications

• F. Schausberger, K. Speicher, A. Steinboeck, M. Jochum, and A. Kugi, Two Illustrative Examples to Show the Potential of Thermography for Process Monitoring and Control in Hot Rolling, in Proceedings of the 4th IFAC Workshop on Mining, Mineral and Metal Processing (MMM), Oulu, Finland, 2015, p. 48–53.
  [BibTex] [Download]

  @InProceedings{Schausberger15c,
  author = {Schausberger, F. and Speicher, K. and Steinboeck, A. and Jochum, M. and Kugi, A.},
  title = {Two Illustrative Examples to Show the Potential of Thermography for Process Monitoring and Control in Hot Rolling},
  booktitle = {Proceedings of the 4th IFAC Workshop on Mining, Mineral and Metal Processing (MMM)},
  year = {2015},
  volume = {48},
  number = {17},
  month = {8},
  pages = {48--53},
  doi = {10.1016/j.ifacol.2015.10.076},
  address = {Oulu, Finland},
  issn = {2405-8963},
  }

• K. Speicher, A. Steinboeck, A. Kugi, D. Wild, and T. Kiefer, A plate temperature model used for planning and online adaptation of the roll pass schedule in hot rolling, in Proceedings of METEC and 2nd European Steel Technology and Application Days (ESTAD), Düsseldorf, Germany, 2015.
  [BibTex]

  @InProceedings{Speicher15,
  author = {Speicher, Katrin and Steinboeck, Andreas and Kugi, Andreas and Wild, D. and Kiefer, T.},
  title = {A plate temperature model used for planning and online adaptation of the roll pass schedule in hot rolling},
  booktitle = {Proceedings of METEC and 2nd European Steel Technology and Application Days (ESTAD)},
  year = {2015},
  month = {6},
  address = {D{\"u}sseldorf, Germany},
  }

• K. Speicher, A. Steinboeck, A. Kugi, D. Wild, and T. Kiefer, Analysis and design of an Extended Kalman Filter for the plate temperature in heavy plate rolling, Journal of Process Control, vol. 24, iss. 9, p. 1371–1381, 2014.
  [BibTex] [Download]

  @Article{Speicher14a,
  Title = {Analysis and design of an Extended Kalman Filter for the plate temperature in heavy plate rolling},
  Author = {Speicher, K. and Steinboeck, A. and Kugi, A. and Wild, D. and Kiefer, T.},
  Journal = {Journal of Process Control},
  Pages = {1371--1381},
  Volume = {24},
  Year = {2014},
  Number = {9},
  Doi = {10.1016/j.jprocont.2014.06.004},
  }

• K. Speicher, A. Steinboeck, D. Wild, T. Kiefer, and A. Kugi, An integrated thermal model of hot rolling, Mathematical and Computer Modelling of Dynamical Systems, vol. 20, iss. 1, p. 66–86, 2014.
  [BibTex] [Download]

  @Article{Speicher14,
  Title = {{An integrated thermal model of hot rolling}},
  Author = {K. Speicher and A. Steinboeck and D. Wild and T. Kiefer and A. Kugi},
  Journal = {Mathematical and Computer Modelling of Dynamical Systems},
  Pages = {66--86},
  Volume = {20},
  Year = {2014},
  Number = {1},
  Doi = {10.1080/13873954.2013.809364},
  }

• K. Speicher, A. Steinboeck, and A. Kugi, Measurement Errors of Radiation Pyrometers, in Proceedings of Rolling 2013, Venezia, Italy, 2013, p. 1–12.
  [BibTex]

  @InProceedings{Speicher13a,
  author = {K. Speicher and A. Steinboeck and A. Kugi},
  title = {{{M}easurement {E}rrors of {R}adiation {P}yrometers}},
  booktitle = {Proceedings of Rolling 2013},
  year = {2013},
  month = {6},
  pages = {1--12},
  address = {Venezia, Italy},
  }

• K. Speicher, A. Steinboeck, D. Wild, T. Kiefer, and A. Kugi, Estimation of plate temperatures in hot rolling based on an extended Kalman filter, in Proceedings of 15th IFAC Symposium on Control, Optimization and Automation in Mining, Mineral & Metal Processing, San Diego, USA, 2013, p. 409 – 414.
  [BibTex]

  @InProceedings{Speicher13,
  author = {K. Speicher and A. Steinboeck and D. Wild and T. Kiefer and A. Kugi},
  title = {{Estimation of plate temperatures in hot rolling based on an extended Kalman filter}},
  booktitle = {Proceedings of 15th IFAC Symposium on Control, Optimization and Automation in Mining, Mineral \& Metal Processing},
  year = {2013},
  month = {8},
  pages = {409 -- 414},
  doi = {10.3182/20130825-4-US-2038.00006},
  address = {San Diego, USA},
  }

• K. Speicher, A. Steinboeck, T. Kiefer, and A. Kugi, Modeling Thermal Shocks and Air Cooling Using the Finite Difference Method, in Proceedings MATHMOD 2012 Vienna, Wien, Austria, 2012, p. 364–368.
  [BibTex]

  @InProceedings{Speicher12,
  author = {K. Speicher and A. Steinboeck and T. Kiefer and A. Kugi},
  title = {{{M}odeling {T}hermal {S}hocks and {A}ir {C}ooling {U}sing the {F}inite {D}ifference {M}ethod}},
  booktitle = {Proceedings MATHMOD 2012 Vienna},
  year = {2012},
  editor = {Troch, I. and Breitenecker, F.},
  month = {2},
  pages = {364--368},
  doi = {10.3182/20120215-3-AT-3016.00064},
  address = {Wien, Austria},
  }

Applications

• Automation of rolling mills
• Scheduling of cooling processes