外文资料--A near-optimal part setup algorithm for 5-axis machining using a parallel.pdf外文资料--A near-optimal part setup algorithm for 5-axis machining using a parallel.pdf

收藏 分享

资源预览需要最新版本的Flash Player支持。
您尚未安装或版本过低,建议您

DOI101007/S0017000318602ORIGINALARTICLEINTJADVMANUFTECHNOL200525130–139JSONGJMOUANEAROPTIMALPARTSETUPALGORITHMFOR5AXISMACHININGUSINGAPARALLELKINEMATICMACHINERECEIVED19FEBRUARY2003/ACCEPTED4JULY2003/PUBLISHEDONLINE28JULY2004SPRINGERVERLAGLONDONLIMITED2004ABSTRACTANEAROPTIMALPARTSETUPMODELNOPSMISDEVELOPEDTHEPURPOSEOFTHISMODELISTOFINDTHENEAROPTIMALPARTSETUPPOSITIONANDORIENTATIONBASEDONTHEWORKSPACE,STIFFNESSANDACCURACYCAPABILITYOFAPARALLELKINEMATICMACHINETHATCANBEUSEDFOR5AXISMACHININGTOBUILDTHEPROPOSEDNOPSM,THEKNOWLEDGEONTHEHEXAPODKINEMATICS,WORKSPACE,STIFFNESS,STRUCTURALIMPERFECTION,NONUNIFORMTHERMALGRADIENTANDACCURACYISREQUIREDTHUS,ITISACOMPREHENSIVEPERFORMANCECAPABILITYSTUDYFORAPARALLELKINEMATICMACHINETHEPROPOSEDMODELISASOFTWARESOLUTIONCONCEPTTOIMPROVETHEMACHINE’SPERFORMANCEITISVERYCOSTEFFECTIVEANDCANALSOBEMODIFIEDFOROTHER5AXISMACHINETOOLAPPLICATIONSKEYWORDS5AXISMACHININGPARALLELKINEMATICPARTSETUPPERFORMANCEENHANCEMENT1INTRODUCTIONMANYCAD/CAMALGORITHMSCANSIMULATETHEMACHININGPROCESSFORSLANTEDANDFREEFORMSURFACESASWELLASGENERATETHECORRESPONDINGNCCODES;HOWEVER,THETRADITIONALTHREEDEGREEOFFREEDOMCNCMACHINERESTRICTSTHEPOTENCYOFTHESEALGORITHMSONEOFTHEADVANTAGESOFPARALLELKINEMATICHEXAPODMACHINEOVERTHETRADITIONAL3AXISMACHINECENTREISITSDEXTERITYANDFLEXIBILITY1–7THEORETICALLY,THEHEXAPODMACHINEUNDERSTUDYPOSSESSESSIXDEGREESOFFREEDOMACTUALLY,THEPLATFORMORIENTATIONAROUNDTHEZAXISCOINCIDESWITHTHEMACHINESPINDLEROTATION;THUS,THISHEXAPODMACHINEHASFIVEEFFECTIVEDEGREESOFFREEDOMFORMACHININGMANYPARTSTHATHAVESLANTEDORFREEFORMSURFACESCANBEGENERATEDONAHEXAPODMACHINEWITHONESETUPANOTHERADVANTAGEOFTHEHEXAPODMACHINEISITSHIGHERSTIFFNESSCOMPAREDTOTHESERIALLINKEDSTRUCTURALMAJSONGJMOUA117DEPARTMENTOFINDUSTRIALENGINEERING,ARIZONASTATEUNIVERSITY,TEMPE,AZ852875906,USAEMAILJIMOUTSMCCOMCHINESOTHATTHEHIGHSPEEDOPERATIONCANBECARRIEDOUTONTHISMACHINE8,9HOWEVER,ADRAWBACKTHATCOMESWITHTHEDEXTERITYOFTHEHEXAPODMACHINEISITSRELATIVELYSMALLWORKSPACELIKEALLMANUFACTURINGEQUIPMENT,IMPERFECTSTRUCTUREANDNONUNIFORMTHERMALGRADIENTRELATEDERRORSALWAYSEXISTTODEGRADETHEMACHINE’SPERFORMANCEINPRODUCINGQUALITYPRODUCTS10–14DUETOTHEUNIQUECHARACTERISTICSOFPARALLELKINEMATICSTRUCTURES,THEMACHINEINACCURACYDISTRIBUTIONWITHINITSWORKSPACEWILLCHANGEASTHEPLATFORMPOSITIONANDORIENTATIONCHANGEMEANWHILE,ITSSTRUCTURALSTIFFNESSVARIESATDIFFERENTPLATFORMPOSITIONSANDORIENTATIONSTHEREFORE,BASEDONTHEINFORMATIONONTHEHEXAPOD’SNOMINALKINEMATICSTRUCTURE,STRUCTURALERRORS,THERMALERRORS,ANDWORKSPACEANDSTIFFNESSANALYSES,ANEAROPTIMALPARTSETUPMODELNOPSMCOULDBEDEVELOPEDTOSUBOPTIMALLYSETUPAPARTWITHINTHEWORKSPACEOFAHEXAPODMACHINETHECONCEPTOFTHISALGORITHMISGENERICANDCANBEEASILYINTEGRATEDWITHEXISTINGKINEMATICANDTHERMALMODELSOFANYOTHERPARALLELKINEMATICMACHINESWITHSIMPLEMODIFICATIONSTHISAPPROACHCOULDALSOBEEMPLOYEDINTHEAPPLICATIONOFSERIALLYLINKEDROBOTSANDMACHINETOOLSFORNOPSM,THEFIRSTCONSTRAINTISTHATALLSURFACESTOBEMACHINEDNEEDTOBELOCATEDWITHINTHEHEXAPOD’SWORKSPACEONCETHEWORKSPACECONDITIONISSATISFIED,THENEXTCRITERIONAPPLIEDTOFINDTHENEAROPTIMALPARTSETUPISTHEHEXAPODMACHINE’SSTIFFNESSANALYSISTOGENERATEHIGHQUALITYPRODUCT,THEPARTNEEDSTOBEPLACEDATTHEMOSTDESIRABLEPOSITIONSOTHATTHEMACHINECANPOSSESSTHEHIGHESTSTIFFNESSANDACCURACYWHILEGENERATINGTHEPARTTHEALGORITHMSDERIVEDIN15TOFINDTHERELATIONSHIPBETWEENTHEMACHINE’SSTRUCTURAL/THERMALERRORSANDITSACCURACYDISTRIBUTIONBASEDONTHEMACHINE’SSTRUCTURALCHARACTERISTICSANDMACHINE’STEMPERATUREGRADIENTPROFILESAREADOPTEDFORSEARCHINGTHENEAROPTIMALPARTPOSITIONINGANDORIENTATIONINPRACTICE,THEHEXAPODMACHINE’SDYNAMICSANDCONTROLSYSTEMSHOULDALSOBECONSIDEREDFORNEAROPTIMALPARTPOSITIONINGSEARCHESHOWEVER,DUETOTHEPROBLEM’SCOMPLEXITYANDTOLIMITATIONSONTHESCOPEOFTHISRESEARCH,WEWILLNOTDISCUSSTHOSETOPICSHERE1312WORKSPACEANALYSISTHEWORKSPACEISTHEWORKINGVOLUMEOFAMACHINEWITHSPECIFICTOOLSANDFEASIBLESPINDLEPOSITIONANDORIENTATIONINORDERTODETERMINETHEUSABLEWORKSPACEOFTHEHEXAPODMACHINE,ADERIVEDKINEMATICMODEL15CANBEAPPLIEDTODETERMINETHESTRUTLENGTH,THEJOINTROTATIONANGLEANDMOBILEPLATFORMPOSITIONANDORIENTATIONTWOCONSTRAINTSARETAKENINTOACCOUNTINTHISWORKSPACEANALYSISFIRST,THEMACHINE’SSTRUTLENGTHLIMITATIONSMAXIMUMLENGTHDEFINETHELOWERBOUNDOFTHEWORKSPACEFIG1HEXAPODMACHINEWORKSPACEANALYSISFLOWCHARTSECOND,THEMACHINE’SSPHERICALJOINTROTATIONALLIMITATIONSDEFINETHEUPPERBOUNDOFTHEWORKSPACEALTHOUGHTHEMACHINE’SMINIMUMSTRUTLENGTHLIMITATIONSHOULDALSOBETAKENINTOCONSIDERATION,THISCONSTRAINTISOVERRIDDENBYTHESPHERICALJOINTROTATIONALLIMITATIONINDETERMININGTHEMACHINE’SUPPERWORKSPACEANALGORITHMFORTHEDETERMINATIONOFHEXAPODWORKSPACEFORASPECIFICPLATFORMORIENTATIONISSHOWNINFIG1DIFFERENTPLATFORMORIENTATIONSHAVEDIVERSEMACHINEWORKSPACEENVELOPESBYUPDATINGTHEORIENTATIONINFORMATION,THEWORKSPACEENVELOPFORDIFFERENTMACHINEPLATFORMORIENTATIONSCANBEDETERMINEDINFIGS2AND3,THEORIENTATIONSAROUNDTHE132FIG2WORKSPACEENVELOPEWITHSPINDLEORIENTATIONANGLE0˚0˚0˚FIG3WORKSPACEENVELOPEWITHSPINDLEORIENTATIONANGLE−30˚0˚0˚YANDZAXESS,ΒANDΓ,AREKEPTCONSTANT;ONLYTHEORIENTATIONANGLEAROUNDTHEXAXIS,Α,ISCHANGEDASTHEORIENTATIONANGLEAROUNDTHEXAXISINCREASES,THEWORKSPACEISTILTEDANDTHEZDIMENSIONOFTHEWORKSPACEENVELOPEISDECREASEDTHELARGERTHEORIENTATIONANGLE,THEMORESEVERETHEWORKSPACETILTINGTHEWORKSPACEANALYSISRESULTSSHOWTHATASIMILARPHENOMENONOCCURSWHENTHEORIENTATIONANGLEAROUNDTHEYAXIS,Β,ISCHANGED,BUTWITHDIFFERENTTILTINGDIRECTIONSINCETHEPLATFORMORIENTATIONANGLEAROUNDTHEZAXIS,Γ,COINCIDESWITHTHESPINDLEROTATINGDIRECTION,THEEFFECTOFΓISSUPERIMPOSEDONSPINDLEROTATIONANDTHUSNOTTAKENINTOCONSIDERATIONINWORKSPACEENVELOPEANALYSISTHENOPSMADOPTSTHEWORKSPACEANALYSISTODETERMINEWHETHERORNOTTHEMACHININGSURFACESAREWITHINTHEHEXAPODWORKSPACETOENSURETHEEFFICIENCYOFTHEALGORITHM,THEFOLLOWINGTWOCONSTRAINTSARETESTEDFORALLTHESELECTEDPOINTSONTHESURFACETOBEMACHINED1THEHEXAPODMAXIMUMSTRUTLENGTHCONSTRAINT2THEHEXAPODMAXIMUMJOINTANGLEROTATIONCONSTRAINTIFALLTHESELECTEDPOINTSONTHEMACHININGSURFACESSATISFYTHEABOVETWOCONSTRAINTS,STRUCTURALSTIFFNESSANDMACHINEACCURACYWILLTHENBEANALYSEDTOIDENTIFYTHENEAROPTIMALPARTSETUPLOCATIONANDORIENTATION3STIFFNESSANALYSISFORAPARALLELMECHANISM,THEREUSUALLYISACLOSEDFORMSOLUTIONFORTHEINVERSEKINEMATICSTHEINVERSEKINEMATICSFORTHEHEXAPODMACHINECOULDBEUSEDTOCALCULATETHESIXSTRUTLENGTHBASEDONTHEPLATFORMPOSITIONANDORIENTATIONINFORMATION16THISCANBEEXPRESSEDASFOLLOWSLIFIX,Y,Z,Α,Β,Γ1THEAPPLICATIONOFTHECHAINRULEYIELDSDIFFERENTIALSOFLII1,2,,6ASFUNCTIONSOFTHEDIFFERENTIALSOFX,Y,Z,Α,Β,ΓΔLI∂FI∂XΔX∂FI∂YΔY∂FI∂ZΔZ∂FI∂ΑΔΑ∂FI∂ΒΔΒ∂FI∂ΓΔΓ2DIVIDINGBOTHSIDESOFEQ1BYTHEDIFFERENTIALTIMEELEMENTΔTANDEXPRESSINGITINMATRIXFORMATYIELDS˙L1˙L2˙L3˙L4˙L5˙L6∂F1∂X∂F1∂Y∂F1∂Z∂F1∂Α∂F1∂Β∂F1∂Γ∂F2∂X∂F2∂Y∂F2∂Z∂F2∂Α∂F2∂Β∂F2∂Γ∂F6∂X∂F6∂Y∂F6∂Z∂F6∂Α∂F6∂Β∂F6∂Γ˙X˙Y˙Z˙Α˙Β˙Γ3NOTETHESTANDARDJOCOBIANEXPRESSION,˙VJ˙LBYLETTING˙LJ−1˙V,THEINVERSEJOCOBIANMATRIX,J−1,FACILITATESTHEMAPPINGOFTHECARTESIANSPACEVELOCITYVECTORVINTOTHESTRUTDISPLACEMENTRATEVECTORAPPLYINGTHEPRINCIPLEOFVIRTUALWORKTOANARBITRARYMECHANISMALLOWSONETOEQUATEWORKDONEINCARTESIANSPACETERMSTOWORKDONEINCONFIGURATIONSPACETERMSSPECIFICALLY,WORKINCARTESIANTERMSISASSOCIATEDWITHACARTESIANFORCE/TORQUEVECTOR,F,APPLIEDATAMECHANISM’STOOLFRAMEANDACTINGTHROUGHANINFINITESIMALCARTESIANDISPLACEMENT,ΔVWORKINCONFIGURATIONSPACETERMSISASSOCIATEDWITHACONFIGURATIONSPACEFORCE/TORQUEVECTOR,F,APPLIEDATAMECHANISM’SJOINTSANDACTINGTHROUGHINFINITESIMALJOINTDISPLACEMENTS,ΔLTHESTIFFNESSOFTHEHEXAPODCANBEDETERMINEDUSINGMATRIXSTRUCTURALANALYSIS,WHERETHESTRUCTUREISCONSIDEREDTOBEACOMBINATIONOFELEMENTSANDNODESTHEDERIVATIONOFTHEHEXAPODSTIFFNESSMODELISBASEDONTHEFOLLOWINGASSUMPTIONS1THEONLYDEFORMATIONOFTHELINKSISINTHEAXIALDIRECTION2THEREISNOBENDINGORTWISTINGOFTHELINKS3THEREISNODEFORMATIONOFTHEJOINTSWORKISCALCULATEDASTHEDOTPRODUCTOFAFORCE/TORQUEVECTORWITHADISPLACEMENTVECTOR,FTΔVFTΔL,WHEREFTF1,F2,F3,F4,F5,F6ARETHEFORCESEXERTEDONEACHOFTHESIX133STRUTSANDFTFX,FY,FZ,MX,MY,MZARETHEFORCESANDMOMENTSACTINGATTHECENTREOFGRAVITYOFTHEPLATFORMNOTETHATΔVJΔL,SOFTJΔLFTΔL⇒FTJFTTRANSFORMINGBOTHSIDESOFTHEEQUATIONYIELDSFTJTF⇒FJTFONECOULDCONCLUDETHAT‘ACTUATING’AMECHANISMWITHAFORCE/TORQUEVECTOR,F,APPLIEDATTHETOOLISEQUIVALENTTOACTUATINGTHATMECHANISMWITHAFORCE/TORQUEVECTOR,F,APPLIEDATTHEJOINTS,WHENTHESAMEAMOUNTOFVIRTUALWORKISDONEINEITHERCASETHERELATIONSHIPBETWEENANAPPLIEDFORCEFATTHETOOLANDTHERESULTINGAXIALFORCESINTHESTRUTFCANBEDEFINEDASFJ−TFGIVENPUREAXIALLOADING,ΕΔLI/LIΣ/EFI/AE⇒FIAE/LIΔLI,WHEREEISTHEELASTICMODULUSOFTHESTRUTMATERIALANDAISTHECROSSSECTIONALAREAOFTHESTRUTINMATRIXFORMAT,FAE/L1000000AE/L2000000AE/L3000000AE/L4000000AE/L5000000AE/L6ΔL4ORFKSΔL,WHERETHEMATRIXISIDENTICALTOTHESTRUTSPACESTIFFNESSMATRIX,KSNOTETHATΔLJ−1ΔV,SOFKSJ−1ΔVANDFJ−TKSJ−1ΔVLETKCJ−TKSJ−1;THENFKCΔV,WHEREKCISTHECARTESIANSPACESTIFFNESSMATRIXBYSETTINGUPANEIGENVALUEPROBLEM,THEPRINCIPLESTIFFNESSAXES,ΗI,ANDPRINCIPLESTIFFNESS,ΚI,CANBEFOUNDASFOLLOWSFKCΔVΚIΔV5KC−ΚII6ΔV06|KC−ΚII6|07HERE,ΗIISINTHEDIRECTIONOFΔVWHERETHEABOVECONDITIONHOLDSTHEPRINCIPLESTIFFNESSΚIWILLCHANGEASPLATFORMORIENTATIONANDPOSITIONCHANGETHEHIGHERTHEMACHINE’SSTRUCTURALSTIFFNESS,THEBETTERTHEPART’SQUALITYANDACCURACY4STRUCTURALERRORDETECTIONMODELASMENTIONEDEARLIER,THEHEXAPODMACHINESTRUCTUREISNOTPERFECT,ANDSTRUCTURALIMPERFECTIONANDASSEMBLYERRORSEXISTTHESTRUCTURALANDASSEMBLYERRORSARENOTDISTRIBUTEDEVENLYAMONGTHEHEXAPODJOINTSANDSTRUTSTHISUNEVENNESSCAUSESDIVERSEACCURACYLEVELSATDIFFERENTPLATFORMPOSITIONSANDORIENTATIONSAFTERAMACHINEISASSEMBLED,ITISDIFFICULTTOMEASURETHEMACHINESTRUCTURALANDASSEMBLYERRORBYUSINGINSTRUMENTSORSENSORSDIRECTLYHOWEVER,THEMACHINEPLATFORM’SORIENTATIONANDPOSITIONCANBEPRECISELYMEASUREDBYUSINGANEXTERNALINSTRUMENTSUCHASA5DLASERINTERFEROMETERSYSTEMORALASERTRACKERSYSTEMAMODELISTHENNEEDEDTOREVERSEIDENTIFYTHEMACHINESTRUCTURALERRORSBASEDONTHEMEASUREDPLATFORMPOSITIONANDORIENTATIONERRORSTHEHEXAPODNOMINALINVERSEKINEMATICSISDERIVEDAS15ΛTMLMTPTRPPBN−TSM;M1,2,,6;NINTM1/28DIFFERENTIATINGTHEEQUATION,SINCEALLTHEVECTORSAREWITHRESPECTTOTHETABLECOORDINATESYSTEM,THESUPERSCRIPTOFTCANBEOMITTEDΔΛMLMΛMΔLMΔPΔRPPBNRPPΔBN−ΔM9TOSIMPLIFYTHECALCULATION,THEROTATIONERRORMATRIXCANBEWRITTENASΔRPΔ˜ΩRP,WHEREΔΩΔΑ,ΔΒ,ΔΓTISTHEORIENTATIONERRORVECTOR,RPISTHENOMINALORIENTATIONMATRIX,ANDΔ˜ΩISDEFINEDASΔ
编号:201311062140153284    类型:共享资源    大小:847.78KB    格式:PDF    上传时间:2013-11-06
  
1
关 键 词:
外文翻译 外文资料 外文文献翻译
  人人文库网所有资源均是用户自行上传分享,仅供网友学习交流,未经上传用户书面授权,请勿作他用。
关于本文
本文标题:外文资料--A near-optimal part setup algorithm for 5-axis machining using a parallel.pdf
链接地址:http://www.renrendoc.com/p-93284.html

当前资源信息

5.0
 
(3人评价)
浏览:79次
admin上传于2013-11-06

官方联系方式

客服手机:17625900360   
2:不支持迅雷下载,请使用浏览器下载   
3:不支持QQ浏览器下载,请用其他浏览器   
4:下载后的文档和图纸-无水印   
5:文档经过压缩,下载后原文更清晰   

精品推荐

相关阅读

人人文库
关于我们 - 网站声明 - 网站地图 - 资源地图 - 友情链接 - 网站客服客服 - 联系我们

网站客服QQ:2846424093    人人文库上传用户QQ群:460291265   

[email protected] 2016-2018  renrendoc.com 网站版权所有   南天在线技术支持

经营许可证编号:苏ICP备12009002号-5