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چكيده انگليسي :

Investigation and Proposing a Model for Work Roll Wear Prediction in Hot Rolling Process Amir Nourani am noorani@me iut ac ir Date of Submission 07 01 2009 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 8311 IranDegree M Sc Language FarsiSupervisor M Salimi Prof salimi@cc iut ac irAbstractRolling is nowadays one of the most important industrial processes because a greater volume of material isworked by rolling than by any other technique Roll wear is a multiplex process where mechanical andthermal fatigues combine with abrasion adhesion and corrosion which all depend on system interactionsrather than material characteristics only Work roll wear in hot rolling process has a substantial effect on stripprofile and shape defect To predict the wear profile it is necessary to be familiar with significant parametersand line actual conditions Appropriate prediction leads to work roll replacement at a suitable time and actualestimation of strip profile In this project wear has been completely introduced and influential parameters have been investigated Also wear mechanisms and their differences in hot strip mill stands have been mentioned Work roll wearhas been categorized to even and uneven wear Definition of strip profile and its elements as well as wearinfluence on the strip profile and ridge buckle defect are illustrated Essential theories due to work roll wearprediction after each pass and after a rolling program as an important goal of this project have beenexplained Two distinct work roll models wear prediction have been proposed The first model is regarding wearprediction after each pass and the second one is to be used after a rolling program In the first model hotrolling process has been modeled by use of finite element method and wear is obtained by means of theresultant pressure distribution during the length of the roll barrel To obtain the wear experimental coefficientin the equation summation wear of each pass was obtained and it was calibrated by the work roll actual wearof a sample tested in the Mobarakeh Steel Company Results were validated by comparing the predicted andactual rolling forces In the second model which was proposed for wear prediction after a rolling program tonnage and weargraphs versus the roll barrel length have been depicted Then the roll barrel was divided into forty equalsegments and the passed tonnage of each segment was obtained according to the passed tonnages and widthsof a rolling program This is the input term for the neural network training while its output is the wearquantity of each segment This training is done via the graphs of work roll wear obtained from theMobarakeh Steel Company This model is based on a large number of industrial experimental results thatwere acquired from roll surface graphs in grinding machine of hot rolling roll shop The fist model is more powerful than the second one because all the influential parameters are taken intoaccount However the second model is better in terms of the solution speed Differences between theoreticaland actual rolling forces in the first model are justified by strip yield stress overestimation and roll flatteningignorance Also differences between the predicted wear profile and the measured contour in the secondmodel can be a consequence of unawareness of some influential wear parameters few numbers of samplesfor neural network training and unpredictable local wears during the length of roll barrel In general theobtained results of two models are reasonable in comparison with the actual results Furthermore predictedwear graphs are found to be in qualitative agreement with the industrial measured ones Key Words wear profile hot rolling work roll FEM neural network

نوراني، امير

بررسي و ارائه مدل پيش بيني سايش غلتك هاي نورد گرم

پروفيل سايش , غلتك كاري , المان محدود , شبكه عصبي