外文翻译--关于食品加工中机械输送系统的设计和制造的一项研究 英文版.pdf -- 5 元

DOI10.1007/s0017000318433ORIGINALARTICLEIntJAdvManufTechnol200525551–559S.H.MasoodB.AbbasE.ShayanA.KaraAninvestigationintodesignandmanufacturingofmechanicalconveyorssystemsforfoodprocessingReceived29March2003/Accepted21June2003/Publishedonline23June2004SpringerVerlagLondonLimited2004AbstractThispaperpresentstheresultsofaresearchinvestigationundertakentodevelopmethodologiesandtechniquesthatwillreducethecostandtimeofthedesign,manufacturingandassemblyofmechanicalconveyorsystemsusedinthefoodandbeverageindustry.Theimprovedmethodologyfordesignandproductionofconveyorcomponentsisbasedontheminimisationofmaterials,partsandcosts,usingtherulesofdesignformanufactureanddesignforassembly.Resultsobtainedonatestconveyorsystemverifythebenefitsofusingtheimprovedtechniques.Theoverallmaterialcostwasreducedby19andtheoverallassemblycostwasreducedby20comparedtoconventionalmethods.KeywordsAssemblyCostreductionDesignDFADFMMechanicalconveyor1IntroductionConveyorsystemsusedinthefoodandbeverageindustryarehighlyautomatedcustommadestructuresconsistingofalargenumberofpartsanddesignedtocarryproductssuchasfoodcartons,drinkbottlesandcansinfastproductionandassemblylines.Mostoftheprocessingandpackagingoffoodanddrinkinvolvecontinuousoperationswherecartons,bottlesorcansarerequiredtomoveatacontrolledspeedforfillingorassemblyoperations.Theiroperationsrequirehighlyefficientandreliablemechanicalconveyors,whichrangefromoverheadtypestofloormountedtypesofchain,rollerorbeltdrivenconveyorsystems.Inrecentyears,immensepressurefromclientsforlowcostbutefficientmechanicalconveyorsystemshaspushedconveyormanufacturerstoreviewtheircurrentdesignandassemblymethodsandlookatanalternativemeanstomanufacturemoreeconomicalandreliableconveyorsfortheirclients.Atpresent,S.H.Masooda117B.AbbasE.ShayanA.KaraIndustrialResearchInstituteSwinburne,SwinburneUniversityofTechnology,Hawthorn,Melbourne3122,AustraliaEmailsmasoodswin.edu.aumostmaterialhandlingdevices,bothhardwareandsoftware,arehighlyspecialised,inflexibleandcostlytoconfigure,installandmaintain1.Conveyorsarefixedintermsoftheirlocationsandtheconveyorbeltsaccordingtotheirsynchronisedspeeds,makinganychangeoveroftheconveyorsystemverydifficultandexpensive.Intodaysradicallychangingindustrialmarkets,thereisaneedtoimplementanewmanufacturingstrategy,anewsystemoperationalconceptandanewsystemcontrolsoftwareandhardwaredevelopmentconcept,thatcanbeappliedtothedesignofanewgenerationofopen,flexiblematerialhandlingsystems2.HoandRanky3proposedanewmodularandreconfigurable2Dand3Dconveyorsystem,whichencompassesanopenreconfigurablesoftwarearchitecturebasedontheCIMOSAopensystemarchitecturemodel.Itisnotedthattheresearchintheareaofimprovementofconveyorsystemsusedinbeverageindustryisverylimited.Mostofthepublishedresearchisdirectedtowardsimprovingtheoperationsofconveyorsystemsandintegrationofsystemtohighlysophisticatedsoftwareandhardware.Thispaperpresentsaresearchinvestigationaimedatimprovingthecurrenttechniquesandpracticesusedinthedesign,manufacturingandassemblyoffloormountedtypechaindrivenmechanicalconveyorsinordertoreducethemanufacturingleadtimeandcostforsuchconveyors.Applyingtheconceptofconcurrentengineeringandtheprinciplesofdesignformanufacturinganddesignforassembly4,5,severalcriticalconveyorpartswereinvestigatedfortheirfunctionality,materialsuitability,strengthcriterion,costandeaseofassemblyintheoverallconveyorsystem.Thecriticalpartsweremodifiedandredesignedwithnewshapeandgeometry,andsomewithnewmaterials.Theimproveddesignmethodsandthefunctionalityofnewconveyorpartswereverifiedandtestedonanewtestconveyorsystemdesigned,manufacturedandassembledusingthenewimprovedparts.2DesignformanufacturingandassemblyDFMAInrecentyears,researchintheareaofdesignformanufacturingandassemblyhasbecomeveryusefulforindustriesthatarecon552sideringimprovingtheirfacilitiesandmanufacturingmethodology.However,therehasnotbeenenoughworkdoneintheareaofdesignforconveyorcomponents,especiallyrelatedtotheissueofincreasingnumbersofdrawingdataandreengineeringoftheprocessofconveyordesignbasedontraditionalmethods.AvastamountofpapershavebeenpublishedthathaveinvestigatedissuesrelatedtoDFMAandappliedtovariousmethodologiestoachieveresultsthatprovedeconomical,efficientandcosteffectiveforthecompaniesunderinvestigation.ThemainclassificationsofDFMAknowledgecanbeidentifiedas1Generalguidelines,2Companyspecificbestpracticeor3Processandorresourcespecificconstraints.Generalguidelinesrefertogenerallyapplicablerulesofthumb,relatingtoamanufacturingdomainofwhichthedesignershouldbeaware.ThefollowinglisthasbeencompiledforDFMguidelines6.DesignforaminimumnumberofpartsDevelopamodulardesignMinimisepartvariationsDesignpartstobemultifunctionalDesignpartsformultiuseDesignpartsforeaseoffabricationAvoidseparatefastenersMaximisecompliancedesignforeaseofassemblyMinimisehandlingdesignforhandlingpresentationEvaluateassemblymethodsEliminateadjustmentsAvoidflexiblecomponentstheyaredifficulttohandleUsepartsofknowncapabilityAllowformaximumintoleranceofpartsUseknownandprovenvendorsandsuppliersUsepartsatderatedvalueswithnomarginaloverstressMinimisesubassembliesFig.1.LayoutofconveyorsystemforlabellingplasicbottlesEmphasisestandardisationUsethesimplestpossibleoperationsUseoperationsofknowncapabilityMinimisesetupsandinterventionsUndertakeengineeringchangesinbatchesThesedesignguidelinesshouldbethoughtofasoptimalsuggestions.Theytypicallywillresultinahighquality,lowcost,andmanufacturabledesign.Occasionallycompromisesmustbemade,ofcourse.Inthesecases,ifaguidelinegoesagainstamarketingorperformancerequirement,thenextbestalternativeshouldbeselected7.Companyspecificbestpracticereferstotheinhousedesignrulesacompanydevelops,usuallyoveralongperiodoftime,andwhichthedesignerisexpectedtoadhereto.Thesedesignrulesareidentifiedbythecompanyascontributingtoimprovedqualityandefficiencybyrecognisingtheoverallrelationshipsbetweenparticularprocessesanddesigndecisions.Companiesusesuchguidelinesaspartofthetraininggiventodesignersofproductsrequiringsignificantamountsofmanualassemblyormaintenance.Notethatmostofthemethodologiesaregoodateitherbeingquickandeasytostartorbeingmoreformalandquantitative.Forexample,guidelinesbyBoothroydandDewhurst8onDFAareconsideredasbeingquantitativeandsystematic.WhereastheDFMguidelines,whicharemerelyrulesofthumbderivedfromexperiencedprofessionals,aremorequalitativeandlessformal9.3ConventionalconveyorsystemdesignDesignandmanufacturingofconveyorsystemsisaverycomplexandtimeconsumingprocess.Aseveryconveyorsystemisacustommadeproduct,eachprojectvariesfromeveryotherprojectintermsofsize,productandlayout.Thesystemdesign553isbasedonclientrequirementsandproductspecifications.Moreover,thesystemlayouthastofitinthespaceprovidedbythecompany.Theprocessofdesigningalayoutforaconveyorsysteminvolverevisionsandcouldtakefromdaystomonthsorinsomeinstancesyears.Onewiththeminimumcostandmaximumclientsuitabilityismostlikelytogetapproval.Figure1showsaschematiclayoutofatypicalconveyorsysteminstalledinaproductionlineusedforlabellingofplasticbottles.Differentsectionsoftheconveyorsystemareidentifiedbyspecifictechnicalnames,whicharecommonlyusedinsimilarindustrialapplication.Thesinglizersectionenablestheproducttoformintoonelanefrommultiplelanes.Theslowdowntablereducesthespeedofproductonceitexitsfromfiller,labeller,etc.Themassflowsectionisusedtokeepupwithhighspeedprocess,e.g.,filler,labeller,etc.Thetransfertabletransfersthedirectionofproductflow.Thepurposeofthesedifferentconveyorsectionsisthustocontroltheproductflowthroughdifferentprocessingmachines.Atypicalmechanicalconveyorsystemusedinfoodandbeverageapplicationsconsistsofovertwohundredmechanicalandelectricalpartsdependingonthesizeofthesystem.Someofthecommonbutessentialcomponentsthatcouldbestandardisedandaccumulatedintofamiliesoftheconveyorsystemaresideframes,spacerbars,endplates,coverplates,insidebendplates,outsidebendplates,bendtracksandshaftsdrive,tailandslave.Thesizeandquantityofthesepartsvaryaccordingtothelengthofconveyorsectionsandnumberoftrackscorrespondingtothewidthandtypesofchainsrequired.Theproblemsandshortcomingsinthecurrentdesign,manufacturingandassemblyofmechanicalconveyorsarevaried,butincludeOverdesignofsomepartsHighcostofsomecomponentsLonghoursinvolvedinassembly/maintenanceUseofnonstandardpartsTable1.ConveyorcriticalpartsbasedonpartscostanalysisProductdescriptionQtyMaterialusedCostImprovementpossibleYes/NoLegset∗68PlasticlegSStube20.22YesSideframe∗802.5mmSS16.07YesSupportchannel∗400CchannelSS15.00YesBendtracks8Plastic14.36NoRt.rollershaft∗13920dia.SSshaft6.70YesTailshaft3935dia.Stainlesssteel6.27NoSpacerbar∗13550X50X6SS5.43YesSupportwearstrip∗4004010mmplastic5.36YesSupportsidewearstrip∗132Plastic3.01YesEndplate392.5mm/SS1.88YesCoverplate391.6mmS/S1.57NoBendplates82.5mm/SS1.29YesTorquearmbracket186mmS/Splate1.21YesSlotcover97Stainlesssteel0.97YesInsidebendplate82.5mm/SS0.66YesTotal100.00∗Criticalparts4AreasofimprovementInordertoidentifytheareasofcostreductioninmaterialandlabour,acostanalysisofallmainconveyorpartswasconductedtoestimatethepercentageofcostofeachpartinrelationtothetotalcostofallsuchparts.Thepurposeofthisanalysiswastoidentifythecriticalparts,whicharemainlyresponsibleforincreasingthecostoftheconveyorandtherebyinvestigatemeansforreducingthecostofsuchparts.Table1showsthecostanalysisofa50sectionconveyorsystem.Theanalysisrevealsthat12outof15partsconstitute79ofthetotalmaterialcostoftheconveyorsystem,wherefurtherimprovementsindesigntoreducethecostispossible.Outofthese,sevenpartswereidentifiedascriticalpartsshownbyanasteriskinTable1constitutingmaximumnumberofcomponentsinquantityandcomprisingover71ofoverallmaterialcost.Amongthese,threecomponentslegset,sideframeandsupportchannelwerefoundtoaccountfor50ofthetotalconveyormaterialcost.Adetailedanalysisofeachofthese12partswascarriedoutconsideringtheprinciplesofconcurrentengineering,designformanufactureanddesignforassembly,andanewimproveddesignwasdevelopedforeachcase10.Detailsofdesignimprovementofsomeselectedmajorcomponentarepresentedbelow.5RedesignoflegsetassemblyInaconveyorsystem,thelegsaremountedonthesideframetokeeptheentireconveyorsystemoffthefloor.Theexistingdesignofconveyorlegswork,buttheyarecostlytomanufacture,theyhavestabilityproblems,andcausedelaysindeliveries.Thedelayisusuallycausedbysomeofthepartsnotarrivingfromoverseassuppliersontime.Themostcriticalspecificationsrequiredfortheconveyorlegsare554StrengthtocarryconveyorloadStabilityEaseofassemblyEaseofflexibilityforadjustingheightFigure2indicatesallthepartsfortheexistingdesignoftheconveyorleg.TheindicatednumbersarethepartnumbersdescribedinTable2,whichalsoshowsabreakdownofcostanalysiscompletewiththelabourtimerequiredtoassembleacompletesetoflegs.Theexistinglegsetupconsistsofplasticlegbracketsorderedfromoverseas,stainlesssteellegtubes,whicharecutintospecifiedsizes,legtubeplasticadjustments,whichareclippedontothelegtubeatthebottomasshowninFig.2.Lugs,whicharecutinsquaresizes,drilledandweldedtothelegtubetobolttheanglecrossbracingandbackingplatetosupportlegbracketsbolts.TheofpartsinTable2signifiesthenumberofcomponentsineachpartnumberandthequantityistheconsumptionofeachpartinthelegdesign.Companieshaveusedthisdesignformanyyearsbutoneofthecommoncomplaintsreportedbytheclientswasoftheinstabilityoflegs.Fromaninitialinvestigation,itbecameclearthattheconnectionbetweenthestainlesssteeltubeandplasticlegsbracketpartFig.2.ExistinglegdesignassemblywithpartnamesshowninTable1Table2.CostanalysisforoldlegdesignassemblyPartno.PartdescriptionofpartsQtyCostSource1Plasticlegbracket2230.00Overseas5,6Legtubeplasticadjustment4228.00Overseas4Lug224.00Inhouse7Anglecrossbracing115.00Inhouse2Backingplate224.00Inhouse3Legtube2225.00Inhouse8Bolts663.00InhouseTotalassemblycostwelding15.00InhouseTotal1917114.001andpart3inFig.2wasnotrigidenough.Theconnectionsforthesepartsareonlyasingle6mmbolt.Attimes,whentheconveyorsystemwascarryingfullproductloads,itwasobservedthattheconveyorlegswereunstableandcausedmechanicalvibration.Oneofthemainreasonsforthiswasduetoasingleboltconnectionateachendofthelugsinpart3andpart7.Thestabilityoftheconveyorisconsideredcriticalmatterandrequiresrectificationimmediatelytosatisfycustomerexpectations.Consideringtheproblemsoftheexistingconveyorlegdesignandtheclientspreferences,anewdesignfortheconveyorlegwasdeveloped.Generallythestabilityandthestrengthofthelegswereconsideredastheprimarycriteriaforimprovementinthenewdesignproposalbutotherconsiderationswerethesimplicityofdesign,minimisationofoverseaspartsandeaseofassemblyatthepointofcommissioning.Figure3shows,thenewdesignoftheconveyorslegassembly,andTable3givesadescriptionandthecostofeachpart.Figure3showsthatthenewdesignconsistsofonlyfivemainpartsfortheconveyorslegcomparedtoeightmainpartsintheolddesign.Intheolddesign,theplasticlegbracket,thelegtubeplasticadjustmentandthelegtubewerethemostexpensiveitemsaccountingfor72ofthecostoflegassembly.Inthenew