THESES OF THE DOCTORAL (PHD) DISSERTATION
MODELING OF ELECTRO-HYDRAULIC ROLL GAP ADJUSTMENT SYSTEM USED IN HOT ROLLING MILL STANDS AND DETECTING THE ACTUATOR’S LEAKAGE
Attila Kővári
Supervisor:
Dr. Dénes Fodor
University of Pannonia Doctoral School in Chemical Engineering and Material Sciences
Veszprém, 2013 1
BACKGROUND AND THE AIM OF THE WORK The implementation of hydraulic gap control in mill stands and its control parameters/features play a key role in terms of the quality of rolled strip. There is a number of mathematical models for analyzing strip rolling. Each model is based on the equation of motion, thermal balance, properties of material, the deformation of mill stands and rolls and can be used for calculating the mechanical tensions, forces, velocity, torque and the change in the temperature of material.
Hot rolling mill stand Having studied scientific references, it may be stated that several models had been developed for both mill stands and hydraulic gap adjustment systems, but these apply a mathematical model describing the non-linear behavior only in part. Based on the reviewed references, this research work aimed at revealing how the internal leakage of the actuator of hydraulic servo system controlling the rolling gap influences the dynamic behavior of the hydraulic gap adjustment system and, as a result, the quality of the rolled material. On the other hand, by using the results, it pursued for determining a mathematical method of such a monitoring procedure from which we can deduce the change in the internal leakage of the hydraulic actuator and the prognosis about the need for the upgrade of the actuator. The gap adjustment can be described with a very complex system hence, in the first phase of the research, the hydraulic positioning system was analyzed in detailed for the purpose of studying the effect on the dynamic behavior exerted by the internal leakage of the hydraulic actuator. Thereafter, the complex model of roll gap adjustment was analyzed by using the derived results and in terms of the effects of the leakage.
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Roll gap control system (AGC: Automatic Gauge Control, HGC: Hydraulic Gap Control) Furthermore, a real-time testing environment - giving the base for performing additional realtime analyses and tests by using this complex mathematical model - was set up among the goals of this research and this environment can be used for carrying out and monitoring realtime dynamic analysis that also cover the hydraulic gap adjustment system.
RESEARCH METHODS In the first step of the research, a general, but adequately detailed mathematical model describing the hydraulic positioning systems was developed, which also includes the description of the internal leakage of the actuator. Then, by using the identified relations and introducing state variables, the model of state space for time series of this dynamic system was determined. Based on the mathematical model, consequences that may be drawn in connection with the effect of the leakage had been confirmed with the measurements made on the servo positioning system installed in the Hydraulics Laboratory of Donát Bánki Faculty of Mechanical and Safety Engineering of Óbuda University. During the measurements the dynamic behavior of the hydraulic servo positioning unit was evaluated with various hydraulic resistance values of throttle simulating the leakage of hydraulic actuator.
Structure of the laboratory hydraulic gap adjustment system
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Laboratory hydraulic positioning system In the second step of the research, the complex mathematical model of the gap control system of mill stands in the hot rolling mill and its simulation was performed by the means of MATLAB Simulink. Based on the results, a parameter monitoring procedure using ARX parameter estimating algorithm was developed and applied for evaluating the real measurement data gained from the automatic gap control system installed in the Hot Rolling Mill of ISD DUNAFERR Zrt.
e[k] y[k] u[k-nk]
Structure of ARX based identification
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RESULTS As the product of this research a mathematical model for a hydraulic servo positioning system was developed that is capable of better approximating reality and includes the description of internal leakage as well as for the analysis of the effect exerted on the dynamic behaviour of the leakage of the hydraulic actuator. Following this, for the purpose of analyzing the dynamic behavior of hydraulic gap adjustment such a complex mathematical model better approximating reality was developed, which also includes the model of internal leakage of the hydraulic system in addition to the description of the processes happening in the hydraulic servo system, the mill stand and the roll gap. This complex model was used for identifying the relationship between the dynamic properties/characteristics of hydraulic gap adjustment and the internal leakage of the hydraulic actuator. A method for monitoring the degree of internal leakage within the hydraulic capsule was developed based on the analyses and with this method a prognosis for the need for hydraulic capsule maintenance can be given. Finally, the real-time implementation of the roll gap control system in the hot rolling mill was developed, in which the dynamic behaviour of mill stands and the effects being difficult to generate or not realizabe at all can be tested in real time.
HIL based test system
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THESES 1. This thesis is to describe how the dynamic behavior of position control system is impaired due to the increase in the internal leakage of a hydraulic actuator by means of using a mathematical model better approximating reality if compared with the general, dynamic, nonlinear models applied for a hydraulic positioning system. 1.1. Having carried out tests, the author shows that the dynamic behavior of the hydraulic gap adjustment used in HRM stands are not negligibly dependent on hydraulic capsule leakage. Furthermore, the decrease in internal leakage resistance of hydraulic capsule impairs the dynamic behavior of hydraulic gap adjustment system, as a consequence it reduces the control rate of automatic gauge control system (AGC), which determines the thickness of rolled strip.
2. I developed a complex mathematical model, which includes the hydraulic servo system, mill stand as well as the deformation phenomena of rolling gap, for the purpose of examining the gap adjustment in stands. This model is suitable for modeling the hydraulic actuator's leakage effects on gap adjustment system. 2.1. I provide a real-time implementation of gap adjustment system by using the complex mathematical model of the roll gap adjustment existing in mill stands with the help of such test environment the dynamic behavior of mill stands and the effects being difficult to generate or not realizable at all can be tested in real time. I determined the minimum sampling time for this test system that is necessary to examine the chattering effects in this dynamic system.
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3. I developed a parameter monitoring method based on parameter estimation algorithm for hydraulic gap control system applied in mill stands. By using this newly developed method, it is possible to draw conclusions for change in the internal leakage of hydraulic capsules based on the measurable parameters of the hydraulic system. The results can be used for predicting the required renewal of hydraulic capsule.
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PUBLICATIONS Publications related to dissertation Journals A. Kővári, Observer Based Leakage Detection of Hydraulic Cylinder Applied in Rolling Mills Electro-Hydraulic Gap Adjustment System, Materials Science, Testing and Informatics VI, Materials Science Forum, Vol. 729, pp. 424-429, trans tech publications inc., 2012, impact factor: 0,399 (2005), Cites per Doc. (2 years): 0,348 (2012) A. Kővári, Dynamic Model of Rolling Mill’s Electro-Hydraulic Gap Adjustment System, Materials Science Forum, Vol. 659, Materials Science, Testing and Informatics V, pp. 411416, trans tech publications inc., 2010, impact factor: 0,399 (2005), Cites per Doc. (2 years): 0,365 (2010) A. Kővári, Real-Time HIL Closed Loop System of Rolling Mill’s Electro-Hydraulic Gap Adjustment, Materials Science, Testing and Informatics V, Materials Science Forum, Vol. 659, Print pp. 417-422, trans tech publications inc., 2010, impact factor: 0,399 (2005), Cites per Doc. (2 years): 0,365 (2010) A. Kővári, Real-Time Modeling of an Electro-Hydraulic Servo System, Computational Intelligence in Engineering, Studies in Computational Intelligence, Vol. 313, pp. 301-311, Springer, 2010
Conferences A. Kővári, D. Fodor, Meleghengerműi hengerállvány hidraulikus résállító rendszer belső szivárgásának identifikáció alapú detektálása, IX. Országos Anyagtudományi Konferencia (OATK 2013), Balatonkenese, Hungary, 13-15 October, 2013 (accepted) A. Kővári, D. Fodor, Tesztkörnyezet meleghengerműi hengerállvány résállításának valósidejű vizsgálatához, IX. Országos Anyagtudományi Konferencia (OATK 2013), Balatonkenese, Hungary, 13-15 October, 2013 (accepted) A. Kővári, D. Fodor, Identification Based Leakage Detection of Hydraulic Capsules, 14th IEEE International Symposium of Hungarian Researchers on Computational Intelligence and Informatics (CINTI 2013), Budapest, Hungary, 19-21 November, 2013 (accepted) A. Kővári, D. Fodor, Elektrohidraulikus szervo rendszer szimulációja, Informatika Korszerű Technikái 2012 (IKT 2012), Dunaújváros, Hungary, 16-17 November, 2012
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A. Kővári, D. Fodor, Simulation of Rolling Mill’s Electro-Hydraulic Gap Adjustment System, 13th IEEE International Symposium of Hungarian Researchers on Computational Intelligence and Informatics (CINTI 2012), Budapest, Hungary, 20-22 November, pp. 377-380, 2012 A. Kővári, D. Fodor, ARMAX based model estimator for Electro-Hydraulic Servo System, 8th International PhD & DLA Symposium, Architectural, Engineering and Information Science, Pécs, Hungary, 29-30 October, pp. 90, 2012 A. Kővári, D. Fodor, ARX model based Fault Detection of Rolling Mill’s Automatic Gauge Control System, 15th IEEE International Power Electronics and Motion Control Conference, EPE-PEMC 2012 ECCE Europe, Novi Sad, Serbia, 4-6 September, pp. DS1d.6-1-DS1d.6-6, 2012 A. Kővári, Elektrohidraulikus szervo rendszer tömítetlenségeinek hatása a hidraulikus henger dinamikus viselkedésére, Tudomány Hete a Dunaújvárosi Főiskolán, Informatikai Konferencia, Dunaújváros, Hungary, 7-11 November, 2011 A. Kővári, Meleghengerlés során a hengerlési rést állító hidraulikus kapszula szivárgásának detektálása, VIII. Országos Anyagtudományi Konferencia (OATK 2011), Balatonkenese, Hungary, 9-11 October, published on CD, 2011 A. Kővári, Hardwer-in-the-Loop Testing of an Electrohydraulic Servo System, 10th International Symposium of Hungarian Researchers on Computational Intelligence and Informatics (CINTI 2009), Budapest, Hungary, 12-14 November, pp. 631-642, 2009 A. Kővári, Mathematical Model and Simulation of Electro-Hydraulic Servo Systems, Tudomány Hete a Dunaújvárosi Főiskolán, Informatikai Konferencia, Dunaújváros, Hungary, 13 November, 2009 A. Kővári, Meleghengerlés hidraulikus résállításának dinamikus vizsgálata a berendezés valósidejű modelljének segítségével, VII. Országos Anyagtudományi Konferencia (OATK 2009), Balatonkenese, Hungary, 11-13 October, published on CD, 2009 A. Kővári, Meleghengerlés hidraulikus résállításának dinamikai modellje, VII. Országos Anyagtudományi Konferencia (OATK 2009), Balatonkenese, Hungary, 11-13 October, published on CD, 2009 A. Kővári, Influence of cylinder leakage on dynamic behavior of electrohydraulic servo system, 7th IEEE International Symposium on Intelligent Systems and Informatics (SISY 2009), Subotica, Serbia, 25-26 September, pp. 375-379, 2009
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Book chapter A. Kővári, Acélhengerész szakmai ismeretek jegyzet szakképesítő tanfolyam hallgatói számára (Automatizálás fejezet), Dunaferr Zrt, Dunaújváros, Hungary, 2006
Publications indirectly related to dissertation Journals A. Kővári, I. Kádár, Reduction Possibilities of Electrical Losses in Plastic Working Equipments, Materials Science, Testing and Informatics V, Materials Science Forum, Vol. 659, pp. 505-510, trans tech publications inc., 2010, impact factor: 0,399 (2005), Cites per Doc. (2 years): 0,365 (2010) A. Kővári, S. Halász, I. Kádár, Frekvenciaváltóról táplált aszinkron motor hibrid áramszabályozása, A Dunaújvárosi Főiskola Közleményei, XXVII/II., Dunaújvárosi Főiskola Kiadói Hivatala, Dunaújváros, pp. 349-357, 2006
Conferences A. Kővári, I. Kádár, Képlékenyalakító berendezések villamos veszteségeinek csökkentési lehetőségei, VII. Országos Anyagtudományi Konferencia (OATK 2009), Balatonkenese, Hungary, 11-13 October, published on CD-n, 2009 A. Kővári, Hybrid Current Control Algorithm for Voltage Source Inverters, 1st IEEE Eastern European Regional Conference on the Engineering of Computer Based Systems, Novi Sad, Serbia, 7-8 Szeptember, pp. 65-70, 2009 A. Kővári, S. Halász, I. Kádár, Frekvenciaváltóról táplált aszinkron motor hibrid áramszabályozása, Magyar Tudomány Hete konferencia sorozat, Informatika Korszerű technikái, Dunaújváros, Hungary, 24-26 November, published on CD, 2005 A. Kővári, S. Halász, I. Kádár, Hibrid invertervezérlő algoritmus feszültséginverterről táplált aszinkron motorokhoz, Energetika Elektrotechnika Konferencia, Cluj-Napoca, Romania, 7-9 October, pp. 76-82, 2005 A. Kővári, S. Halász, I. Kádár, The Influence of Inverter Control Algorithm and DC Link Voltage on the Inverter Switching Loss, IEEE International Conference on Industrial Technology, Hammamet, Tunisia, 8-10 December, Vol. 2., pp. 590-595, 2004 A. Kővári, S. Halász, I. Kádár, Inverterről táplált mezőorientált szabályozású aszinkron motoros szervo hajtások kapcsolási veszteségeinek vizsgálata, Energetika Elektrotechnika Konferencia 2003, Cluj-Napoca, Romania, 3-5 October, pp. 113-119, 2003
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A. Kővári, S. Halász, I. Kádár, Inverter switching loss of induction motor drive at different control methods, 8CLEEE 8th Portuguese-Spanish Congress in Electrical Engineering, Vilamoura, Portuguese, 3-5 July, pp. 6.103-6.108, 2003 A. Kővári, I. Schmidt, I. Kádár, Influence of control strategy on the inverter switching loss, Kandó International Conference 2002, Budapest, Hungary, 14-15 November, published on CD, 2002 A. Kővári, I. Schmidt, I. Kádár, Current-control of induction motor drives: comparison of inverter control methods, IEEE Postgraduate Power Conference ’02, Budapest, Hungary, 1114 August, pp. 45-50, 2002
Books Z. Jeges, J. Haluska, A. Kővári, Villamosságtan, Dunaújvárosi Főiskola Kiadói Hivatala, Dunaújváros, Hungary, 2007 Z. Jeges, J. Haluska, A. Kővári, Tanulási útmutató a „Villamosságtan” című tárgyhoz (példatár), Dunaújvárosi Főiskola Kiadói Hivatala, Dunaújváros, Hungary, 2007 P. Odry, J. Haluska, A. Kővári, Digitális technika, Dunaújvárosi Főiskola Kiadói Hivatala, Dunaújváros, Hungary, 2007 P. Odry, J. Haluska, A. Kővári, Tanulási útmutató a „Digitális technika” című tárgyhoz (példatár), Dunaújvárosi Főiskola Kiadói Hivatala, Dunaújváros, Hungary, 2007
Other publications Journals Kővári A., Dukán P., Felhő alapú energiamenedzsment, avagy okos mérők a Weben (Cloudbased Energy Services, Smart Meters in the Web), Elektrotechnika folyóirat, 106. évfolyam, 2013/03 szám, pp. 10-11, Magyar Elektrotechnikai Egyesület, 2013
Conferences A. Kővári, Elektromos meghajtású szelepek fizikai szimulációs laboratóriumának bemutatása, Kutatási és oktatási terek fejlesztése a Dunaújvárosi Főiskolán, Dunaújváros, Hungary, 25 April, 2013 A. Kővári, D. Péter, Szerverek terheltségének megállapítása Fuzzy logika alkalmazásával, Informatika Korszerű Technikái 2012 (IKT 2012), Dunaújváros, Hungary, 16-17 November, 2012
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A. Kővári, P. Dukan, Performance Analysis of Allwinner A10 ARM Processor Based MeLE A1000 Mini PC with Linux OS, IEEE 13th International Symposium of Hungarian Researchers on Computational Intelligence and Informatics (CINTI 2012), Budapest, Hungary, 20-22 November, pp. 381-384, 2012 A. Kővári, P. Dukan, KVM & OpenVZ virtualization based IaaS open source cloud virtualization platforms: OpenNode, Proxmox VE, IEEE 10th Jubilee International Symposium on Intelligent Systems and Informatics (SISY 2012), Subotica, Serbia, 20-22 September, pp. 335-339, 2012 A. Kővári, Elektromos meghajtású szelepek fizikai szimulációs laboratóriuma, Kutatási és gyakorlati képzési terek fejlesztése a Dunaújvárosi Főiskolán, Dunaújváros, Hungary, 26 March, 2012 A. Kővári, TMS320F2812-es DSP programozása MATLAB Simulink grafikus blokkorientált környezetben, Magyar Tudomány Hete konferencia sorozat, Informatikai Konferencia, Dunaújváros, Hungary, 12-16 November, published on CD, 2007 D. Bakos, A. Kővári, Elektronikus vezérlőegység (ECU) tervezése Suzuki gyártmányú gépkocsi motorhoz, Graduate Conference’ 2000, Budapest, Hungary, 26 April, pp. 61-66, 2000 A. Kővári, D. Bakos, Designing Electronic Control Unit (ECU) for Suzuki Made Engines, microCAD’ 2000 International Computer Science Conference, Section C, Miskolc, Hungary, 23-24 February, pp. 1-6, 2000
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