طراحي بهينه ي برنامه ي زمان بندي در نورد گرم ورق به منظور كمينه كردن سايش

چكيده انگليسي :

132Optimum Design of Mill Scheduling in Hot Strip Rolling for Minimizing the Wear Crown Zahrasadat Fatemi Zahrasadat fatemi@me iut ac ir Date of Submission 2015 08 18 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisors Mohammad Reza Forouzan forouzan@cc iut ac irSupervisors Mohammad Reza Niroomand niroomand@es isfpnu ac irAbstract In metalworking rolling is a metal forming process in which metal stock is passed through one ormore pairs of rolls to reduce the thickness and to make the thickness Rolling is classified according to thetemperature of the metal rolled If the temperature of the metal is above its recrystallization temperature then the process is known as hot rolling If the temperature of the metal is below its recrystallizationtemperature the process is known as cold rolling In the hot strip mills a typical challenge is the rollingtime schedule which plays an important role in cost reduction delivery time and quality improvement Inthis research optimum design of scheduling problem in hot rolling is investigated This problem includesselecting a number of slabs from slab yard and determining their best sequence for sending into hot rollingmill Since this feature requires the study of all possible permutation in slab selection the complexity of theproblem space is very large Thus the solution for this optimization problem is very complex The problemhas been designed based on the production conditions in the largest steel production facility in Iran Mobarakeh Steel Complex MSC In this study in contrast to the previous studies that concentrated on therolling timing schedule mechanical considerations are focused as well The mechanical wear parameter ischosen as the main cause to terminate each program in the optimization problem Mathematical formulationof the problem is performed in MATLAB software using the actual data from the mill Four differentformulations are introduced Formulation uses the basic idea of Travelling Salesman Problem TSP andthree dynamic packages that are programmed by the author The travelling salesman problem is a classicalgorithmic problem in the field of computer science It is focused on optimization In this context bettersolution often means a solution that is cheaper It is most easily expressed as a graph describing thelocations of a set of nodes The first formulation uses binary variables The second formulation uses integervariables third formulation checks out smaller categories of all slabs permutations and the forth checks outall the possible permutations To solve the optimization problem genetic algorithm is utilized In this study two different objective functions are used Maximizing the number of slabs is chosen as the first objectivefunction and minimizing the wear crown of the work roll is chosen as the second objective function Moreover reducing width jump and thickness jump are considered as the optimization constraints Toreduce the computation time penalty method is used for replacing a constrained optimization problem tounconstrained problem At the end the accuracy and efficiency of the offered program is compared withother programs being used in the hot strip mill unit of the Mobarakeh Steel Complex The result of thiscomparison shows that the created model compared with previous models reduces wear and thereby reduces costs and increases production efficiency Keywords Hot rolling Scheduling Wear crown Optimization Genetic algorithm Traveling salesman problem Penalty function Slabs Sequence permutation

فاطمي، زهراسادات

طراحي بهينه ي برنامه ي زمان بندي در نورد گرم ورق به منظور كمينه كردن سايش

تاج سايشي , الگوريتم ژنتيك , مسئله ي فروشنده ي دوره گرد , تابع جريمه , توالي تختال ها , جايگشت