بررسي نقش ارتعاشات افقي غلتك ها در ناپايداي چتر نورد سرد دو قفسه اي به منظور بهينه سازي پارامترهاي نورد

چكيده انگليسي :

Investigations on Rolls Horizontal Vibration on Chatter Instability in 2 Stands Cold Rolling Mill inorder to Optimize Process Parameters Mohammad Reza Abdoli m reza abdoli@me iut ac ir Date of Submission 2012 04 3 Department of Mechanical Engineering IsfahanUniversity of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisor Mohammad Reza Forouzan forouzan@cc iut ac irAbstract Rolling industry is being considered as a one of the most important and profitable industries in theworld More than 90 percent of steel products have been already rolled Self exciting vibration of the rollingmills with constant or rising amplitude is called chatter vibration Chatter phenomenon is one of the majorproblems in this industry Chatter or undesirable vibration of the rolling stands not only affects anddegreades the quality of the sheets but also decreases the efficiency of the rolling lines significantly Considering large investments in this industry chatter is an undesirable phenomenon for the owners of thisindustry Knowing the identity of self excited vibrations in cold strip rolling lines and studying the factorsthat can arise them has consistently been one of the important aims of rolling technology researchers Thisstudy tries to simulate and recognize the chatter phenomenon to speed up the lines without the occurrenceof chatter A new structural model is developed which allows rolls to vibrate horizontally This model is a2 dimentional model based on the Hue model It considers 2 degree of freedom for each roll The horizontaleffects come from centerline angle of the work roll and the backup roll which is not perpendicular to therolling line Then by studying the interaction between structure and process models chatter vibrations havebeen simulated By using the Taguchi method series of simulations have been designed for various rollingcircumstances and by using artificial neutral network the relation between the threshold velocity and othereffective parameters has been identified In the last step of the research the output speed of the last standwhich indicates the production volume has been maximized as the target function It is worthy to mentionthat in all steps constraints and constants has been applied to 2 stands cold rolling line by consultingMobarakeh steel company experts The results obtained from optimization show more 20 increase inoutput speed of rolling sheet For model verification data from two stands reversing cold rolling mill ofMobarake Steel Company MSC have been used Two stand tandem mill unit is responsible for thereduction of the sheet thickness in the ambient temperature Incoming coils have thickness of about 2 mm The coil passes through two 4 roll stands in a regressive way after it has been opened and loses its thicknessby 60 90 percent as a result of 2 3 rolling passes and is coiled by the coiler machine The second pass isin reverse direct All the condition of rolling are measured using tens sensors and saved as digital andanalogue signals Then the simulations results were compared to applicable information of 2 stands coldrolling line and an acceptable accordance was observed For optimization verification the optimizationresults were checked in the simulatiuon program which already has been verified by experimentalmeasurements Keywords Rolling Industry vibration chatter phenomenon optimization

عبدلي، محمدرضا

بررسي نقش ارتعاشات افقي غلتك ها در ناپايداي چتر نورد سرد دو قفسه اي به منظور بهينه سازي پارامترهاي نورد

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