Unit 11 Rapid Prototyping and Manufacturing Technologies.ppt

Unit11RapidPrototypingandManufacturingTechnologies IntroductionManufacturingcommunityisfacingtwoimportantchallengingtasks 1 Substantialreductionofproductdevelopmenttime and 2 Improvementonflexibilityformanufacturingmulti varietyandsmallbatch sizeproducts Computer aideddesignandmanufacturinghavesignificantlyimprovedthetraditionalproductiondesignandmanufacturing However thereareanumberofobstaclesintrueintegrationofcomputer aideddesignwithcomputer aidedmanufacturingforrapiddevelopmentofnewproducts Tosubstantiallyshortenthetimefordevelopingpatterns moulds andprototypes somemanufacturingenterpriseshavestartedtouserapid 社团 团体 大量的 可观的 障碍 母模 模具 样件 原型 prototyping RP methodsforcomplexpatternsmakingandcomponentprototyping Overthepastfewyears avarietyofnewrapidmanufacturingtechnologies generallycalledRapidPrototypingandManufacturing RPthetechnologiesdevelopedincludestereolithography SL selectivelasersintering SLS fuseddepositionmodeling FDM laminatedobjectmanufacturing LOM andthreedimensionalprinting 3DPrinting ThesetechnologiesarecapableofdirectlygeneratingphysicalobjectsfromCADdatabases Theyhaveacommonimportantfeature theprototypepartisproducedbyaddingmaterialsratherthanremovingmaterials thatis apartisfirstmodeledbyageometricmodelersuchasasolidmodeler andthenismathematicallysectioned sliced intoaseriesofparallelcross sectionpieces Foreachpiece thecuringorbindingpathsaregenerated Thesecuringorbindingpathsaredirectlyusedtoinstructthemachineforproducingthepartby 快速原型技术 光固化成型 激光 烧结 熔结 分层实体制造 几何建模软件 切片 切片 横截面 烤 粘合 熔融沉积成型 三维打印成型技术 solidifyingorbindingalineofmaterial Afteralayerisbuilt anewlayerisbuiltonthepreviousoneinthesameway Thus themodelisbuiltlayerbylayerfromthebottomtotop RPProcessesAsmentionedearlier thereareseveraltechnologiesavailableformodelproductionbasedontheprincipleof growing or additive manufacturing Themajordifferencesamongthesetechnologiesareintwoaspects 1 Materialsused and 2 Partbuildingtechniques Thefollowingsectionswillexplainindetailtheserapidprototypingtechnologieswithrespecttotheabovetwoaspects 1 StereolithographyStereolithographyapparatus SLA wasinventedbyCharleHullof3DSystemsInc itisthefirstcommerciallyavailablerapidprototypeandisconsideredasthe 使变硬 使成为固体 光固化成型机 mostwidelyusedprototypingmachine Thematerialusedisliquidphoto curableresin acrylate Undertheinitiationofphotons smallmolecules monomers arepolymerizedintolargemolecules Basedonthisprinciple thepartisbuiltinavatofliquidresinasshowninFig11 1 TheSLAmachinecreatestheprototypebytracinglayercross sectionsonthesurfaceoftheliquidphotopolymerpoolwithalaserbeam UnlikethecontouringorzigzagcuttermovementusedinCNCmachining thebeamtracesinparallellines ThelaserbeamisdeflectedhorizontallyinXandYaxesbygalvanometer drivenmirrorssothatitmovesacrossthesurfaceoftheresintoproduceasolidpattern Afteralayerisbuilt theelevatordropsauser specifieddistanceandanewcoatingofliquidresincoversthesolidifiedlayer Awiperhelpsspreadtheviscouspolymeroverforbuildingthenextlayer Thelaserdrawsanewlayeronthetopofthepreviousone Inthisway themodelisbuiltlayerbylayerfrom 树脂 丙烯酸 启动 光子 分子 单体 聚合 描摹 光聚合物 使偏离 偏斜 电流计 检流计 升降机 刮板 粘稠的 聚合物 大桶 大缸 光敏的 bottomtotop thereareseveralfeaturesworthyofmentioningofSLA 1 Material Therearefivecomerciallyavailablephotopolymers Allofthemareakindofacrylate 2 Support Becauseamodeliscreatedinliquid theoverhangingregionsofthepart unsupportedbelow maysagorfloatawayduringthebuildingprocess Theprototypethusneedssomepredesignedsupportuntilitiscuredorsolidified Theseadditionalfeaturesarebuiltonthemodelpartsandhavetobetrimmedafterthemodelbuildingiscompleted 3 Modelaccuracyandperformance Theaccuracyachievedisabout0 14 oftheoveralldimensionanddeteriorateswithlargersizesbutnomorethan0 5 Thelayerthicknessisbetween0 004 and0 03 Presently theSLAmachines 悬吊的 下沉 下陷 功能 部件 修剪 变坏 恶化 厚度 性能 光聚合物 丙烯酸 madeby3DSystemsInc arethemostaccuratemachinesamongtheRP Msystems 2 Selectivelasersintering SLS SLSusesacarbondioxidelasertosintersuccessivelayersofpowderinsteadofliquid InSLSprocesses athinlayerofpowderisappliedbyarotatingrollermechanismontotheworkplace Thepowdermaterialispreheatedtoatemperatureslightlybelowitsmeltingpoint Thelaserbeamtracesthecross sectiononthepowdersurfacetoheatupthepowdertothesinteringtemperaturesothatthepowderscannedbythelaserisbonded Thepowderthatisnotscannedbythelaserwillremaininplacetoserveasthesupporttothenextlayerofpowder whichaidsinreducingdistortion Whenalayerofthecross sectioniscompleted therollerlevelsanotherlayerofpowderoverthesinteredoneforthenextpass 二氧化碳 连续的 粉末 滚子 碾子 预热 熔点 扫描 使粘合 变形 弄平 Exercises TranslatethefollowingwordsintoEnglish 快速原型制造技术 模具 原型 样件 光固化成型 母模 几何建模软件 树脂 光子 分子 聚合物 RapidPrototypingandManufacturingTechnology mould prototype stereolithography pattern geometricmodeler resin photon molecule polymer 粉末 二氧化碳 熔点 powder carbondioxide meltingpoint TranslatethefollowingwordsintoChinese substa