Numerical Investigation of a Process Control for the Roller Levelling Process Based on a Force Measurement

Abstract:

When processing conventional semi-finished metal strips, distinctive changes in the material properties along the strip length are unavoidable. The roller levelling process is sensitive to changes of those strip characteristics. Thus, a process control allowing for an online adaption of the roller levelling machine according to the actual strip characteristics is highly desirable. In order to enable a precise process layout, the calculation by the Finite Element Method (FEM) provides a suited strategy. Furthermore, the coupling of user-subroutines to an FE code offers the possibility to implement and test respective control strategies. This work proposes a control strategy that is based on a force measurement in the first load triangle of a levelling machine. A first FE model including a feedback control is used to calculate the dependence between the force in the first load triangle and the roll intermesh in the last load triangle leading to a flat sheet. The results are transferred to meta models – so called control curves – that give a direct relationship between the measured force and the roll intermesh. Within a second FE setup a feed-forward control based on these control curves is implemented and the proposed control strategy is investigated for varying yield strengths along the strip length. Thus, the time consuming FE simulations that are necessary to obtain the control curves are decoupled from the actual levelling process. According to the obtained results, the introduced approach is able to improve the sheet flatness for thin sheets when a change in the material properties occurs.

• Periodical: Materials Science Forum (Volume 854)
• Pages: 249-254
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.854.249
• Online since: May 2016
• Authors: Markus Grüber*, Gerhard Hirt
• Keywords: Finite Element Method (FEM), Process Control, Roller Levelling

References

[1] J.W. Morris, S.J. Hardy, J.T. Thomas, Some fundamental considerations for the control of residual flatness in tension levelling, JMPT 120 (2002) 385-396.

DOI: 10.1016/s0924-0136(01)01175-x

[2] H. Huh, J.H. Heo, H.W. Lee, Optimization of a roller levelling process for A17001T9 pipes with finite element analysis and Taguchi method, Int. J. of Mach. Tools & Man. 43 (2003) 345-350.

DOI: 10.1016/s0890-6955(02)00269-9

[3] J.W. Morris, S.J. Hardy, J.T. Thomas, Effects of tension levelling process parameters on cold rolled strip characteristics using a designed factorial analysis approach, Ironmaking and Steelmaking 32/5 (2005) 443-448.

DOI: 10.1179/174328105x48089

[4] H. Huh, H.W. Lee, S.R. Park, G.Y. Kim, S.H. Nam, The parametric process design of tension levelling with an elasto-plastic finite element method, JMPT 113 (2001) 714-719.

DOI: 10.1016/s0924-0136(01)00661-6

[5] L. Steinwender, A. Kainz, K. Krimpelstätter, K. Zeman, Numerical Simulation of Tension Losses and Reaction Forces in Tension Levellers, SRI, Special Edition (2011) 343-348.

[6] F. Yoshida, M. Urabe, Computer-aided process design for the tension levelling of metallic strips, JMPT 89-90 (1999) 218-223.

DOI: 10.1016/s0924-0136(99)00034-5

[7] E. Doege, R. Menz, S. Huinink, Analysis of the levelling process based upon an analytic forming model, CIRP Annals – Manufacturing Technology 51/1 (2002) 191-194.

DOI: 10.1016/s0007-8506(07)61497-8

[8] B. -A. Behrens, R. Krimm, Controlled Sheet Metal Straightening, Supplemental Proceedings 3, TMS (2008) 129-136.

[9] R. Haberland, G. Lauer, A sensor system for the controlled roller levelling machine for sheet metal, Blech Rohre Profile 40/7 (1993) 599-601.

[10] L. Bodini, O. Ehrich, M. Krauhausen, Improvements at heavy plate leveller by coupling a model to a flatness gauge, Stahl und Eisen 128/6 (2008) 47-50.

[11] A. Pernía, F.J. Martínez-de-Pisón. J. Ordieres, F. Alba, J. Blanco, Fine tuning straightening process using genetic algorithms and finite element methods, Ironmaking and Steelmaking 37/2 (2010) 119-125.

DOI: 10.1179/030192309x12549935902301

[12] M. Oligschläger, G. Hirt, Implementation of Closed-loop Control Systems in Finite Element Simulations of Roller Leveling, SF2M Con. Proc. (2012) 43-44.

[13] R. Kaiser, T. Hatzenbichler, B. Buchmayr, T. Antretter, Simulation of the roller straightening process with respect to residual stresses and the curvature trend, Materials Science Forum 768-769 (2014) 456-463.

DOI: 10.4028/www.scientific.net/msf.768-769.456

[14] Y. Cho, H. Ye, S. Hwang, A New Model for the Prediction of Evolution of the Residual Stresses in Tension Leveling, ISIJ International 53/8 (2013) 1436-1442.

DOI: 10.2355/isijinternational.53.1436

[15] B. -A. Behrens, T. El Nadi, R. Krimm, Development of an analytical 3D-simulation model of the levelling process, JMPT 211 (2011) 1060-1068.

DOI: 10.1016/j.jmatprotec.2011.01.007

[16] B. Dratz, V. Nalewajk, J. Bikard, Y. Chastel, Testing and modelling the behaviour of steel sheets for roll levelling applications, International Journal of Material Forming 2/1 (2009) 519-522.

DOI: 10.1007/s12289-009-0560-3

[17] M. Grüber, M. Oligschläger, G. Hirt, Adjusting of Roller Levellers by Finite Element Simulations Including a Closed-loop Control, Advanced Materials Research 1018 (2014) 207-214.

DOI: 10.4028/www.scientific.net/amr.1018.207