Modeling and control of hot levelers

Project focus

• Modeling, identification and analysis of the mechanical and hydraulic components of the leveler
• Optimal, active compensation of the elastic deformation
• Design of control strategies for the dynamic positioning of the leveler

Description

Hot levelers are used in hot rollings mills for steel plates. After rolling and cooling, a leveling machine reduces remaining flatness errors and residual stresses in the plates. Between the work rolls of the hot leveler, the plates undergo plastic deformations through alternating excessive bending.

Hot leveler with bending mechanism.

The leveling forces can reach several meganewtons and lead to deformations of the leveler in the range of several millimeters. For quality reasons, these deformations have to be compensated, e.g., by means of actuators or a bending mechanism. At the same time, overloading the leveler must be avoided.

The modeling and analysis of the mechanical and hydraulic configuration of the leveler are of interest. Essential parts of the mathematical model are the elastic deflection of the machine as well as friction forces which occur in the hydraulic actuators and the joints of the bending mechanism.

The work rolls are modeled as Euler-Bernoulli beams. They are elastically supported by the support rolls, the sub-frames, and the posts, where the deflection models of these components are represented by compliance matrices. The deflection model was validated by measurements with instrumented plates. A reduced finite-dimensional model is used to determine an optimal deflection compensation. By means of an optimization algorithm the adjustment of the actuators is calculated such that the desired plate curvature is optimally reached. With the optimization approach the mechanical load is directly constrained and thus overloading the leveler is avoided. For the calculation of the leveling load a nonlinear leveling model is used.

The precise adjustment of the rolls by means of the bending mechanism is crucial for an effective deflection compensation. Based on a validated mathematical dynamical model of the mechanism, a control law was developed, which reliably adjusts the rolls even under friction and operating loads.

The developed solution has been successfully implemented at an industrial hot leveler for heavy plates.

Selected publications

• R. Brauneis, M. Baumgart, A. Steinboeck, and A. Kugi, Deflection Model Of A Multi-Actuator Gap Leveler, in Proceedings of the 20th IFAC World Congress, Toulouse, France, 2017, pp. 11295-11300.
  [BibTex] [Download]

  @InProceedings{Brauneis17,
  author = {Brauneis, R. and Baumgart, M. and Steinboeck, A. and Kugi, A.},
  title = {Deflection Model Of A Multi-Actuator Gap Leveler},
  booktitle = {Proceedings of the 20th IFAC World Congress},
  year = {2017},
  volume = {50},
  number = {1},
  month = {7},
  pages = {11295-11300},
  doi = {10.1016/j.ifacol.2017.08.1647},
  address = {Toulouse, France},
  issn = {2405-8963},
  }

• M. Baumgart, A. Steinboeck, T. Kiefer, and A. Kugi, Modelling and experimental validation of the deflection of a leveller for hot heavy plates, Mathematical and Computer Modelling of Dynamical Systems, vol. 21, iss. 3, p. 202–227, 2015.
  [BibTex] [Download]

  @Article{Baumgart15a,
  Title = {Modelling and experimental validation of the deflection of a leveller for hot heavy plates},
  Author = {Baumgart, M. and Steinboeck, A. and Kiefer, T. and Kugi, A.},
  Journal = {Mathematical and Computer Modelling of Dynamical Systems},
  Pages = {202--227},
  Volume = {21},
  Year = {2015},
  Number = {3},
  Doi = {10.1080/13873954.2014.941881},
  }

• M. Baumgart, A. Steinboeck, A. Kugi, G. Raffin-Peyloz, L. Irastroza, and T. Kiefer, Optimal Active Deflection Compensation of a Hot Leveler, in Proceedings of the IFAC Workshop on Automation in the Mining, Mineral and Metal Industries, Gifu, Japan, 2012, p. 30 – 35.
  [BibTex]

  @InProceedings{Baumgart12,
  author = {M. Baumgart and A. Steinboeck and A. Kugi and G. Raffin-Peyloz and L. Irastroza and T. Kiefer},
  title = {{O}ptimal {A}ctive {D}eflection {C}ompensation of a {H}ot {L}eveler},
  booktitle = {Proceedings of the IFAC Workshop on Automation in the Mining, Mineral and Metal Industries},
  year = {2012},
  month = {9},
  pages = {30 -- 35},
  doi = {10.3182/20120910-3-JP-4023.00009},
  address = {Gifu, Japan},
  }

• M. Baumgart, A. Steinboeck, A. Kugi, B. Douanne, G. Raffin-Peyloz, L. Irastroza, and T. Kiefer, Modeling and Active Compensation of the Compliance of a Hot Leveler, steel research international, vol. Special Edition ICTP2011, p. 337–342, 2011.
  [BibTex]

  @Article{Baumgart11a,
  Title = {{Modeling and Active Compensation of the Compliance of a Hot Leveler}},
  Author = {M. Baumgart and A. Steinboeck and A. Kugi and B. Douanne and G. Raffin-Peyloz and L. Irastroza and T. Kiefer},
  Journal = {steel research international},
  Pages = {337--342},
  Volume = {Special Edition ICTP2011},
  Year = {2011},
  }

• M. Baumgart, A. Steinboeck, A. Kugi, G. Raffin-Peyloz, B. Douanne, L. Irastorza, and T. Kiefer, Active compliance compensation of a hot leveler, in Proceedings of the 4th International Conference on Modelling and Simulation of Metallurgical Processes in Steelmaking, STEELSIM, METEC InSteelCon 2011, Düsseldorf, Germany, 2011.
  [BibTex]

  @InProceedings{Baumgart11,
  author = {M. Baumgart and A. Steinboeck and A. Kugi and G. Raffin-Peyloz and B. Douanne and L. Irastorza and T. Kiefer},
  title = {Active compliance compensation of a hot leveler},
  booktitle = {Proceedings of the 4th International Conference on Modelling and Simulation of Metallurgical Processes in Steelmaking, STEELSIM, METEC InSteelCon 2011},
  year = {2011},
  month = {6},
  address = {D\"usseldorf, Germany},
  }

Applications

• Rolling mill automation
• Press equipment/forming machinery