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Analysis of the clad sheets rolling Mahan Qwamizadeh m qwamizadeh@me iut ac ir Date of Submission 2010 4 11 Department Collge of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiMahmoud Salimi salimi@cc iut ac irMahmoud Kadkhodaei kadkhodaei@cc iut ac irAbstractAsymmetrical plane strain rolling in which the radius surface roughness and surface velocity of the upper andlower rolls are different has become one of the interesting processes in forming the sheets in steel industries Despite many useful and desirable advantages asymmetrical sheet rolling experiences the disadvantage ofbending the sheet at entry to and exit from the roll gap Beside inlet and outlet regions in this type of rolling athird zone is called cross shear region CSR exists within the roll gap which have essential effects on thereduction of rolling force and torque as well as tilting the sheet at exit Cross shear region is the zone laidbetween two neutral points of the rolls and in this region the direction of surface frictions is not according toeach other In this analysis it is assumed that the forming is under the plane strain condition and no materialspreads is occurred in transverse direction Considering this assumption it is shown that the maximum error incalculated results would be less than 7 dependent on width to contact length ratio of the sheet The mechanicalbehavior of material is assumed to be perfectly plastic with no strain hardening and Von mises criteria areassumed to explain the plastic region The results show that the outgoing curvature in free and forced horizontalentry of the sheet may be different and adjusting the rolling conditions to have free horizontal entry may lead tomore curvature Clad sheets are the ones that are formed by bonding of two layers of sheets Rolling of cladsheets can be categorized in asymmetrical rolling processes because the physical characteristics of clad sheetsare shifty along the sheet thickness Clad sheet rolling is one of the most important methods of forming sheetsthat are made from two or more metallic layers The properties of clad sheet depend on properties of theircomponent metallic layers For example a clad sheet made of steel and cupper is a sheet that has a combinationof strength of steel and thermal specification of cupper In this paper rolling of bi layer sheets that are linkedtogether before conducting to the rolling space has been studied Owing to the different yield stress of the cladsheet layers the nature of clad sheet rolling is essentially asymmetric In this thesis a solution basd on the slabmethod of analysis is given in which the non uniformity of normal and shear stresses across the sections of thedeforming material all through the plastic region in deriving the governing equations and the yield criterion areconsidered Two models are used to analyze the rolling process of clad sheets in which different friction modelssuch as sticking coulomb and a combination of such models are used A quadratic distribution is assumed forshear stress for each element within the roll gap and the curvature of the sheet is calculated in the departuresection Comparision of the results of the proposed model and those of the experimental investigations verifiesthat in most cases predictions of the present model are more realistic than those has been proposed by the otherinvestigators This model is an all purpose one considers no restriction and limitations in asymmetricalconditions Keywords Clad sheet rolling slab method strip curvature Asymmetrical rolling

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