环境下的电话机底座模具设计外文翻译Word下载.docx
- 文档编号:19415265
- 上传时间:2023-01-06
- 格式:DOCX
- 页数:9
- 大小:26.33KB
环境下的电话机底座模具设计外文翻译Word下载.docx
《环境下的电话机底座模具设计外文翻译Word下载.docx》由会员分享,可在线阅读,更多相关《环境下的电话机底座模具设计外文翻译Word下载.docx(9页珍藏版)》请在冰豆网上搜索。
专业材料成型及控制工程
学生姓名
班级材控08-1
学号
指导教师
AutomatedGenerationofLifters
forInjectionMoulds
Y.F.Zhang,H.H.LiuandK.S.Lee
DepartmentofMechanicalEngineering,NationalUniversityofSingapore,RepublicofSingapore
Analgorithmforautomatedidentificationofundercutsandthecreationoftheliftersubassemblyinplasticinjectionmoulddesignisdescribed.Thealgorithmissuitableforinjectionmoulddesignina3Dmode.Theinputtothesoftwareisa3Dpartmodel,partingdirectionandlines,andamould-base.Thesoftwarethengeneratestheliftersubassemblyandplacesitproperlyinthemould-base.Thisisaccomplishedinfoursteps.First,theso-calledvirtualcoreandcavityaregeneratedwithoutconsideringanyundercuts.Undercutfacesonthepartarethenidentifiedandundercutgroupsareformed.Secondly,thereleasingdirectionofeachundercutgroupisfound.Thirdly,foreachundercutgroup,alifterheadbasedonitsreleasingdirectioniscreated.Fourthly,otherstandardcomponentsofalifterassemblyareretrievedandattachedtothecorrespondinglifterheadwithinthemould-baseatthecorrectlocation.Acasestudyispresentedthatillustratestheefficacyofthetechniquefortheautomateddesignoflifterstofulfilarealindustrialrequirement.
Keywords:
CAD;
Injectionmoulddesign;
Lifter;
Undercut
1.Introduction
Asonemethodforthemanufactureofplasticparts,injectionmouldinghasbeenwelldeveloped.Aninjectionmouldassembly,typicallyconsistsofamouldbase,runners,coreandcavity,coolingchannels,ejectors,andotherauxiliarycomponents.Amongthesefunctionalparts,thecoreandcavity,whichformtheshapeofthemoulding,areatthecentreofamould.Anundercutisanyportionofthemouldingthatpreventsitfrombeingextractedfromtheimpression,alongthepartingdirection.Anundercutadjacenttothecavityisusuallyreferredtoasanexternalundercut,andoneadjacenttothecoreasaninternalundercut.Foranexternalundercut,aslidermechanism,suchasafingercamortogglecamcanbeadopted.Foraninternalundercut,aliftermechanismisprobablythemostcommonlyusedmethod.Thismechanismisillustratedbytheexampleshown.Duringtheejectionstroke,thelifterisdriveninwards,therebywithdrawingtheobstructionandallowingthemouldingtobeextractedinthepartingdirection.
Traditionally,moulddesignistypicallycarriedoutonthedrawingboardorbyusing2Dcomputer-aideddrawingpackages.Withthedevelopmentof3Dcomputer-aideddesign(CAD)techniques,productdesignandNCtool-pathgenerationarecommonlycarriedoutinthe3Dmode.Itisthereforedesirabletodesignthemouldinthe3Dmode,inordertoshortentheleadtime.Recently,ithasbeenobservedthatseveralCADpackages,suchasIMOLD,weredevelopedtomeetsuchaneed.Thesepackagesprovidesomecommonlyusedmouldlayoutsandvariouscomponentlibrariesfortheusertochoosefrom.Thedesigntasksinvolvinggeometricreasoning,suchassliderandlifterdesign,arestillperformedinteractively.Therehasalsobeensomepublishedworkonundercutdetectionandthedesignofsidecores(sliderandlifter).However,thereportedautomationtechniquesarestillatanexperimentalstage.Noneofthemhavebeenreportedinanyindustrialapplication.Thispaperfocusesontheautomatedidentificationofinternalundercutsandthegenerationoflifers.However,thetechniquedevelopedcouldbeextendedtothedesignofsliders.
2.PreviousWork
Intheareaofidentificationandresolvingundercutsformoulddesign,mostofthepublishedworkfocusesonsearchingfortheoptimalpartingdirectionandthepartinglines,inordertominimisethenumberofundercuts.Therearealsoafewreportedtechniquesonhowtoincorporatesidecorestoresolveundercuts.Thefollowingsectionsreviewsomeofthepreviousworkinthesetwocategories.
2.1OptimisationofPartingDirectionandLines
Theselectionofthepartingdirectionandthepartinglinesofapartiscriticaltothemoulddesign,asthedecisionwilldecidethenumberofundercuts,andultimatelyaffectthecostofthemould.RaviandSrinivasanproposedasetofcriteriathataffectthepartingdirectionandlineselection.Fromageometricpointofview,thepossiblecandidatesforsuchselectionareinfinite.Variousknowledge-basedoroptimizationschemeshavebeenproposed.
HuiandTandevelopedaheuristic-basedapproachfordeterminingpartingdirectionsbasedonthebalanceofthepreferencevalue(theratiooftheprojectedareainagivendirectiontothemaximumprojectedarea)andtheblockingfactor.SawaiandKakazuconstructedasimilarevaluationfactorbyintersectingvectorsalongacandidatepartingdirectionfromrandomlycreatedpointsonthepartmodel,coupledwithageneticalgorithm.Chenetal.employedthevisibilitymapmethodtoidentifypotentialundercuts,leadingtotheselectionoftheoptimalpartingdirection.
Oneproblemwiththeabovemethodsisthatoptimisingthepartingdirectionwithoutconsideringpartinglinesisincomplete,asapotentialundercutcouldbeavoidedbyappropriatelyplacingthepartinglines.Tanetal.presentedamethodforgeneratingpartinglinesbyaddingartefactstoverticalsidefaceswithrespecttothepartingdirection.However,thistaskhastobedonebytheuser.Atpresent,thetechniquesreportedfortheautomaticdeterminationofthepartingdirectionandlinesarestillfarfrommature.
2.2ResolvingUndercuts
Oncethepartingdirectionandlinesaredetermined,themouldcoreandcavitycanbegeneratedbysubtractingthepartfromablockandsubsequentlysplittingtheblockalongthepartingsurface.Atthislevel,thecoreandcavityarereferredtoasvirtualcore(v-core)andvirtualcavity(v-cavity),astheslidersandliftersareyettobeincorporated.Inrespecttothepartingdirection,theundercutsonboththev-coreandthev-cavitycanbeidentified,andslidersand/orliftersdesigned.
ShinandLeepresentedamethodthatidentifiesundercutfacesfromthev-coreandthev-cavity.Sidecoresaregeneratedbymanuallyspecifyingthereleasingdirections.Thev-coreandv-cavityarethenmodifiedtoincorporatethesidecores.Rosenalsodevelopedanalgorithmusingasimilarapproachforcreatingslidersandlifters.Strictlyspeaking,theslidersandliftersgeneratedbybothoftheabovemethodsareonlyatanabstractlevel,whichisfarfrombeingusableinindustry.
Manymoreaspectsmustbeconsideredanddesignedtomakethemechanismacompletefunctionalpartinthewholemouldassembly.
Thepresentstudyaimsatcreatingcompleteliftersubassembliesforindustrialuse.Inindustrialpractice,thepartingdirectionandlinesaremainlypredeterminedbytheplasticpartdesigner,ratherthanbythemoulddesigner.Apartfromthenumberofundercuts,theappearanceofthepartinglineonthepartisalsoanimportantfactortoconsider.Thepresentalgorithmtakesthev-coreandthev-cavityastheinput.Inaddition,themould-basewhichistobeusedtoincorporatetheliftersubassemblyisalreadydetermined.First,thesilhouettecurvesofthefacesonthev-core,withrespecttothepartingdirection,areextractedandusedtosplitthecorrespondingfaces.Secondly,undercutfacesarederivedbasedontheirsurfacenormalandgroupedintoindividualundercuts.Thirdly,releasingdirectionsareidentifiedforeachundercut.Fourthly,foreachundercut,alifterheadisgeneratedbasedonitsreleasingdirection.Finally,otherstandardcomponentsareselectedandaddedtoeachlifterheadtoformawholeliftersubassembly.
3.IdentifyingInternalUndercuts
Onthev-core,afacethatisadjacenttothepartsurfaceisreferredtoasaCoF.Themovingdirectionofthecoreduringmouldopeningisspecifiedby“PD-”.Forlifterdesign,thefirststepistoextractundercutfacesfromallCoFs.Ideally,thenormalateverypointonaCoFshouldbechecked.ApointwhosenormalhasapositiveelementalongPD-issaidtobeblockedduringmouldopening,anditsparentCoFisaundercutface.However,itispossiblethatnotallthepointsonaundercutfaceareblocked,andacompletesearchofallthepointsisnotpossible.Therefore,weproposeapreprocessingmethodfortheCoFs.TheideaistosplitaCoFsothatthepointsoneachresultingfacehaveahomogeneousnormalelementalongPD.Toachievethat,thesilhouettecurvesoneachCoFinrespecttoPD-areextractedandusedtosplittheCoF.Foreachresultingface,asinglepointischecked.Ifitisblocked,itsparentfaceandsubsequentlytheparentCoFisanundercutface.ThisapproachisfurtherillustratedbytheexampleshowninFig.3.Theparthastwoundercuts,oneofthemhasafreeformsurface.Figure3(d)showstheextractedsilhouettecurvesandthefourfacesaftersplittingwheretwoofthemarefoundtobeundercutfaces.
OncealloftheindividualundercutCoFsareidentified,thenextstepistoallocatethemtodifferentundercutgroups(UGp),whereeachUGpcanbehandledbyasinglelifter.Sincealiftermovesalongitslateraldirectionduringmouldopening,anytwoundercutCoFsthatareoverlapping,viewedfromthepartingdirection,shouldbehandledbyasinglelifter.Althoughinindustrialpractice,twoormoreUGpsfoundusingthisheuristicaresometimeshandledbyasinglelifter,suchpracticedependsmainlyonthedesigner’sexperienceandthusisnotconsideredinthisstudy.IneachUGp,theundercutCoFsmaynotbeadjacent(ortheycannotbesewedintoasingleface).Insuchcases,thenon-undercutCoFsthatareadjacenttotheundercutCoFswillbeidentifiedandaddedtotheUGp.Finally,theCoFsinanUGparese
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- 环境 电话机 底座 模具设计 外文 翻译