Ch4_Rolling(1).pdf0

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1、Chapter4:RollingReference:Kalpakjian,chap.13Dr.MichelNganbeMCG43284.Rolling4.1.IntroductiontoRolling4.2.Microstructurechangesduringhotrolling4.3.Rollingprocessandrollingforces4.4.Othercharacteristicsofrollingandpotentialdefects4.5.GeometrychangeandrollingspeedMCG4328;Dr.

2、MichelNganbe24.Rolling4.1.4.1.Introductiontorolling4.1.Introductiontorolling4.1.Introductiontorolling
Rollingistheprocessofreducingthethicknessand/orchangingthecross-sectiongeometryofamaterialusingcompressiveforcesappliedthroughasetofrolls.
Rollingcanbeperformed:•Hot:usu

3、allyfirststepinprocessingingots.Itismostappropriateforlargethicknessreductions(plates>6mm;sheets<6mm)andforthemanufactureofprofiles:L•Cold:isoftenusedasfinalrollingstep.Generallylimitedtothreads,sheets,orsimplebarshapes:
Rollingvs.machiningforthreads:•Advantageofrolling:

4、lowercostsandnoscrap;coldworkedsurfacemeanshighhardnessandlowwear;compressivesurfacestressesimprovefatigueresistance•Disadvantageofrolling:largersurfaceroughnessandnotappropriateforaccuratepositioningMCG4328;Dr.MichelNganbe34.Rolling4.1.4.1.Introductiontorolling4.1.Intro

5、ductiontorollingFigure13.1Schematicoutlineofvariousflat-rollingandshape-rollingprocesses.Source:AftertheAmericanIronandSteelInstitute.MCG4328;Dr.MichelNganbe44.Rolling4.1.4.1.Introductiontorolling4.1.IntroductiontorollingFigure13.12StepsintheshaperollingofanH-sectionpart

6、.Variousotherstructuralsections,suchaschannelsandI-beams,alsoarerolledbythiskindofprocess.MCG4328;Dr.MichelNganbe54.Rolling4.1.4.1.Introductiontorolling4.1.IntroductiontorollingFigure13.13Twoexamplesoftheroll-forgingoperation,alsoknownascross-rolling.Taperedleafspringsan

7、dknivescanbemadebythisprocess.Source:AfterJ.Holub.MCG4328;Dr.MichelNganbe64.Rolling4.1.4.1.Introductiontorolling4.1.IntroductiontorollingFigure13.15(a)Schematicillustrationofaring-rollingoperation.Thicknessreductionresultsinanincreaseinthepartdiameter.(b-d)Examplesofcros

8、s-sectionsthatcanbeformedbyring-rolling.MCG4328;Dr.MichelNganbe74.Rolling4.1.4.1.Introductiontorolling4