بررسي علل و عوامل سخت افزاري نوسانات نيرو در قفسه هاي نورد گرم در تست كاليبراسيون

چكيده انگليسي :

Investigation onto vibration signals of hot rolling stands due to structural defects in calibration test Amir Hossein Zehtabchi a zehtabchi@me iut ac ir April 4 2009 Department of Mechanical Engineering Isfahan University of Thechnology Isfahan 84156 83111 IranDegree M Sc Language FarsiDr H Khademyzadeh supervisor hkhademyza@cc iut ac irDr M Ghayour supervisor ghayour@cc iut ac irAbstractCalibration test is carried out to check the perfectness of the main rolling equipments on hot rolling mill stands In calibration test rolls are loaded to the forces in the same order of rolling force for few seconds and then to thehalf of the mentioned force for few more seconds while no strip is fed between the rolls Calibration test shouldbe performed after every roll change or after failure of computer systems Rolling conditions can be estimatedfrom the test results and this test can be used as a powerful tool to judge whether rolling process is permissibleor not The main goal of this research is to distinct the structural defects of the mill from force vibrations which arerecorded by Ida analyzer during calibration test As the vibration diagrams of Iba Analyzer show constantamplitude it is concluded that forced vibration was occurred on the mill For approach to this goal mathematical model are represented and then differential equations are derived Structural model consists of two sub models vertical model and torsional model Vertical model has twodegrees of freedom and torsional model has one degree of freedom Equations of motion for vertical modelinclude linear vertical stiffness coefficient and linear vertical damping coefficient Equation of motion fortorsional model includes equivalent mass moment of inertia equivalent torsional damping coefficient andequivalent torsional stiffness coefficient At next step structural defects affect on constituted model Structuraldefects consist of two items Some structural defects affect on vertical model and the defects of them wereshown by forces such as eccentricity on rolls ovality on rolls and various defects in bearings and somestructural defects effect on torsional model and the defects of them were shown by moments such asmisalignment in gear couplings various defects in gears and rolling resistance Then ultimate equations whichare coupled with each other were solved using Simulink tool box of and Matlab software Results of simulationswere compared with real data from Iba Analyzer Comparison were done using FFT technique to find peakvibration amplitude on any oscillation frequency Conclusions are Forced vibration due to hardware errors are the source of the observed oscillations on Iba data Defects which affect vertical sub model such as eccentricity and ovality of the rolls are detectable by thecalibration test Defect amplitude could be calculated using the method which is presented on this thesis In reverse structural defects which appear as oscillating moments and affect the tortional sub model does nothave considerable effect on force vibration in calibration test Examples of these defects are misalignment ingears couplings shafts etc Key WordsCalibration test force vibration structural defect hot rolling mill rolls

زهتابچي، امير حسين

بررسي علل و عوامل سخت افزاري نوسانات نيرو در قفسه هاي نورد گرم در تست كاليبراسيون

غلتك ها , مجتمع فولاد مباركه