主講人：趙慧、楊國星TianjinLightIndustryVocationalTechnicalCollege1.DimensioningthepartdrawingPartIDimensionalDatumsPARTIDimensionalDatumPointLineSurfaceThestartingpointformeasuringthedimensionsofapartduringdesign,manufacturing,andinspectioniscalledtheDimensionalDatum.TheDatumPoint

designdatumprocessdatumDimensionalDatuma.DesignDatumTypesofDimensionalDatums

01

Fromthedesignperspective,adesigndatumisselectedtomeetthestructuralandperformancerequirementsofthepartwhenitisinstalledinamachineorcomponent.D---DesignDatumintheWidthDirectionC--DesignDatumintheLengthDirectionB--DesignDatumintheVerticalDirectionDimensionalDatumb.ProcessDatum

TypesofDimensionalDatums

01AxialProcessDatumChuckDatumProcessDatum車刀

Fromtheperspectiveofthemanufacturingprocess,aprocessdatumisselectedtofacilitatethemachiningandmeasurementofthepart.Thesearespecificreferencepointschosentoassistinthemanufacturingandmeasurementprocessofthecomponent.DimensionalDatumSelectionofDimensionalDatums

02Thedesigndatumandtheprocessdatumshould,asfaraspossible,coincideinordertoreducedimensionalerrorsandensureproductquality.SelectionPrinciplesMostpartshavedimensionaldatumsinthreedirections:length,width,andheight.However,forpurelyrotationalbodies,onlytwodirectionsofdimensionaldatumsareused:radialandaxial.Three-PointDatums

Apartmayhavetwoormoredatumsinonedirection.Typically,thereisonlyoneprimarydatum,andtheothersaresecondaryorauxiliarydatums.Themostimportantgeometricfeaturesofthepartshouldbeselectedastheprimarydatum.PrimaryandSecondaryDatumsPartIIIssuestoConsiderWhenProperlyAnnotatingDimensionsPARTIIIssuestoConsiderWhenProperlyAnnotatingDimensionsDirectlyannotatefunctionaldimensions

01Thefunctionaldimensionsofapart,alsoknownastheprimarydimensions,refertothedimensionsthataffectthemachinespecifications,performance,workaccuracy,andtheprecisepositioningofthepartwithinanassembly,aswellasdimensionsthatrequirefits.Thesedimensionsshouldbedirectlyannotatedandnotderivedbycalculation.SlotFitsUnreasonableReasonableIssuestoConsiderWhenProperlyAnnotatingDimensionsGenerally,closeddimensionchainsshouldbeavoided.

02Closeddimensionchain

Theleastimportantdimensioninthedimensionchainshouldnotbemarked.IncorrectCorrectIssuestoConsiderWhenProperlyAnnotatingDimensionsConsiderationofeaseandfeasibilityofmeasurement

03DifficulttomeasureEasytomeasureIssuestoConsiderWhenProperlyAnnotatingDimensionsDimensionsfromthesameprocessshouldbegroupedtogetherforannotation.03PartIIICommonHoleDimensioningMethodsonPartsPARTIIICommonHoleDimensioningonPartsCommonHoleDimensioningonPartsRecessedHoleStraightHoleCountersunkHole

"6×φ7"meansthatthereare6holes,eachwithadiameterofφ7.Thediameterofthelargeendoftheconicalpartisφ13,andtheconeangleis90°.CounterboreHoleFortherecessedplaneφ20,thedepthdoesnotneedtobemarked.Duringprocessing,therecessedareaisgenerallymachineduntilnoburrsarepresent.Foursmallcounterboredholeswithadiameterofφ6.4,andalargeholediameterofφ12,depthof4.5.DescriptionSideAnnotationMethodGeneralAnnotationMethodStructuralTypesCommonHoleDimensioningonPartsSummaryofthisLectureDimensioningDatumsIssuestoConsiderforProperDimensioningCommonHoleDimensioningonPartsThinkingQuestionPleasecompletethedimensioningofthepartdrawing.主講人：趙慧、楊國星TianjinLightIndustryVocationalTechnicalCollege2.ReadingandInterpretingTechnicalDrawingsofPartsIntroductionThenameofthepart,material,anddrawingscaleUnderstandingthedrawingIdentifyingthedimensionsandpositionsofvariouspartsofthecomponentUnderstandingthemeaningsofvarioussymbols,codesonthedrawing,aswellastheprocessingmethodsandtechnicalrequirementsofthepart.

PartIMethodsandStepsforReadingDrawingsPARTIMethodsandStepsforReadingDrawings01ReviewtheTitleBlockUnderstandthebasicinformationsuchasthepart’sname,material,anddrawingscale.Relateittotheclassificationoftypicalpartstoformaninitialunderstandingofthepart.02

AnalyzetheViewsAnalyzetheviewstounderstandtheinternalandexternalstructuralshapesofthepart,whichisthekeyfocuswhenreadingadrawing.AnalyzetheviewrepresentationschemeAnalyzetheprojectionsandvisualizethestructureandshapeofthepart.Followtheseprinciples:Startwiththeprimary,thenthesecondaryfeatures;Startwiththeoverallstructure,thenthedetails;Startwiththesimplerparts,thenthemorecomplexones.MethodsandStepsforReadingDrawings03AnalyzeDimensionsandTechnical

RequirementsAccordingtothepart’sstructure,identifythedimensionalreferencesinthe

length,width,andheightdirections.04

SummarizeandConcludeIntegratethepart’sstructuralshapes,dimensionannotations,andtechnicalrequirementstofullyunderstandthepart—thismeanstrulycomprehendingthepartdrawing.PartIIReadingPartDrawingsPARTIIReadingPartDrawingsCheckingtheTitleBlock

01Thenameofthepartispumpbody,classifiedasabox-typepart.ThematerialisHT150,andthedrawingscaleis1:2.ReadingPartDrawingsAnalyzingtheViews

02Identifythefrontviewandanalyzetheprojectionrelationshipsbetweentheviewsandtheexpressionmethodsused.Thefrontviewisafullsectionalview;thetopviewisapartialsectionalview;theleftviewshowstheexternalshape.ThepumpbodyU-shapedcylindricalshellwithaninternalcylindricalcavityusedtohouseotherparts.Twotriangularmountingplateslocatedatthefrontandrearofthepumpbody.Twocylindricalthreadedoilinletandoutletports,locatedontherightsideandrearsideofthepumpbody,respectively.ReadingPartDrawingsAnalyzingDimensionsandTechnicalRequirements

03LengthReferenceHeightReferenceWidthReferenceFirst,identifythedimensionalreferencesforthelength,width,andheightdirections,thendeterminethemaindimensions.Thelengthreferenceistheendfaceofthemountingplate.Thewidthreferenceisthefront-to-rearsymmetryplaneofthepumpbody.Theheightreferenceisthetopendfaceofthepumpbody.Thedimensions47±0.1and60±0.2arethemaindimensionsandmustbestrictlyensuredduringmachining.ThedimensionsoftheinletandoutletportsareM14×1.5-7HandM33×1.5-7H,bothbeingfine-pitchstandardthreads.ThesurfaceroughnessRavaluesoftheendfacesare3.2μmand6.3μm,respectively,whicharerelativelyhighrequirementstoensuretightexternalconnectionsandpreventoilleakage.ReadingPartDrawingsSummarizingandConcluding

04Throughtheanalysiscarriedoutintheprevioussteps,adetailedunderstandingofthepumpbodypart’sstructuralshapeanddimensionshasbeenachieved.Additionally,acomprehensiveunderstandingofthematerialsusedformanufacturingthispartandalltherelatedtechnicalrequirementshasbeenobtained.Bysynthesizingandsummarizingthisinformation,acompleteoverallconceptofthepumpbodypartcanbeformed.Furthermore,itallowsfordeeperanalysisoftherationalityofthepart’sstructureandmanufacturingprocess,theappropriatenessoftherepresentationmethods,thecorrectnessofthedimensioning,andwhetheranyerrorsoccurredduringthedrawinginterpretation,inordertobetterunderstandthetechnicaldrawing.SummaryofThisLectureReviewtheTitleBlockAnalyzetheViewsanalyzetheDimensionsandTechnicalRequirementsSummarizeandConcludeThinkingQuestionPleasecompletetheinterpretationoftheright-sideflangeaccordingtothemethodforreadingpartdrawings.主講人：趙慧、楊國星TianjinLightIndustryVocationalTechnicalCollege3.SelectionoftherepresentationmethodofthepartPartIIntroductionPARTIIntroductionPartIITheFunctionandContentofPartDrawingsPARTIITheFunctionandContentofPartDrawingsWhenmanufacturingmachines,allpartsmustfirstbeproduced.Partsarethebasicunitsthatmakeupamachineorcomponent.Apartdrawingisatechnicaldiagramusedtorepresentthestructuralshape,size,andtechnicalrequirementsofapart.Itisanimportanttechnicaldocumentthatdirectlyguidesthemanufacturingandinspectionofparts.

Duringtheproductionprocess,partdrawingsareusedforproductionpreparation,processing,manufacturing,andinspection.TheFunctionandContentofPartDrawingsSetofViews:Acompleteandclearrepresentationofthepart'sstructureandshape.OverallDimensions:Representtheshape,size,andrelativepositionsofvariouspartsofthecomponent.TechnicalRequirements:Indicateorspecifythetechnicalperformancerequirementsthatthepartshouldmeetduringitsuse,manufacture,andinspection.TitleBlock:Includesinformationsuchasthepartname,material,drawingnumber,scale,drafter,reviewer,andotherrelevantdetails.PartIIIMethodsofRepresentingPartPARTIIIMethodsofRepresentingPartAnalyzetheStructuralShapeFunctionManufacturingMethodDeterminingtheMethodandStepsforPartRepresentationAnalyzethePartChoosetheFrontViewSelectOther

ViewsMethodsofRepresentingPartsSelectionoftheFrontViewShapeFeaturesProcessingPositionWorkingPositionofthePartNaturalPlacementofthePartMethodsofRepresentingPartsSelectionoftheFrontViewPrincipleofShapeFeaturesWhichdirectionshouldbechosenasthemainviewdirection?MethodsofRepresentingPartsSelectionoftheFrontViewWhenthepartisbeingmachined,itmustbefixedandclampedinaspecificpositionforprocessing.Whenchoosingthefrontview,itshouldideallyalignwiththepart'smachiningpositiontofacilitateviewingformanufacturing.WorkpieceRotationLatheProcessingoftheShaftMethodsofRepresentingPartsSelectionoftheFrontView(2)PrincipleofProcessingPositionMethodsofRepresentingPartsSelectionoftheFrontView(3)PrincipleofWorkingPosition

Partsareinstalledonmachinesinspecificworkingpositions.Theadvantageofaligningthefrontviewwiththeworkingpositionisthatitfacilitatescomparisonwiththeassemblydrawingforbothviewinganddrafting.

Forpartslikesupports,housings,etc.,whichhavevaryingmachiningmethodsandpositions,theworkingpositionistypicallyusedasthereference.Themainviewprojectiondirectionshouldalignwiththepart’sworkingpositionforeasycomparisonwiththeassemblydrawing.MethodsofRepresentingPartsSelectionoftheFrontView(4)PrincipleofNaturalPlacementIfthepartisamovingcomponent,withanunfixedworkingpositionormultiplemachiningstagesandvariableprocessingpositions,themainviewcanbedrawnbasedonthepart’snaturallystableplacement.MethodsofRepresentingPartsSelectionofOther

Views？AnalyzebasedonthespecificsituationAfterthefrontviewisdetermined,additionalviewsshouldbeselectedtofullyandclearlyrepresentthestructuralshapeandrelativepositionsofthepart’scomponents.Dependingontheinternalandexternalstructureofthepart,othernecessaryviews,suchassectionalviewsorcutawayviews,shouldbechosentodepictspecificstructuralaspectsofthepart.Thenumberofviewsshouldbeminimizedtofacilitatedrawingandreadingthedrawings.Forapart,oncethefrontviewisdetermined,howmanyadditionalviewsareneededtoclearlyexpressit?Question:Conclusion:SummaryofThisLectureTheFonctionandContentofPartDrawingsMethodsofRepresentingPartsReflectionQuestionPleasethinkabouttherepresentationschemeforthishousingpart.主講人：趙慧、楊國星TianjinLightIndustryVocationalTechnicalCollege4.ProcessstructureofthepartIntroductionThestructuralshapeofapartisprimarilydeterminedbyitsfunction,position,anditsrelationshipwithotherpartswithinthemachine(orassembly).Atthesametime,itisalsonecessarytoconsidertheconvenienceofprocessing,manufacturingandassembly.Somestructuresonpartsdesignedtomeettheprocessneedsofprocessing,manufacturing,assemblyandmeasurementarecalledtheprocessstructureofparts.CastingProcessStructureMainContentMachiningProcessStructurePartICastingProcessStructurePARTICastingProcessStructureDraftAngleIncastingproduction,tofacilitatetheremovalofthewoodenpatternfromthesandmold,acertainangleistypicallydesignedinthedirectionofthepattern'sremoval.Thisangleisknownasthedraftangle.Thecastingalsohasacorrespondingdraftangle.Thedraftanglemaynotbeshownorindicatedonthedrawing,but,ifnecessary,itcanbespecifiedinthetechnicalrequirements.CastingProcessStructureDraftAngleTopreventsandfromfallingoffatthesharpcornersofthesandmoldwhenremovingthepattern,andtoavoiddefectssuchascracksandshrinkageholesatthesharpcornersofthecasting,castingfilletsareappliedattheintersectionsofallsurfacesofthecasting.Shrinkage

cavityCracksUnreasonableCastingFilletReasonableCastingProcessStructureCastingFilletTheradiusofthecastingfilletisgenerallynotindicatedonthedrawing,butisspecifiedinthetechnicalrequirements.Ifacastingfilletisremovedbymachining,thesurfaceshouldbedrawnasasharpcorner.MachinedtoaSharpCornerCastingProcessStructureCastingWallThicknessDuringthepouringprocessofthecasting,inordertopreventdefectssuchasshrinkagecavitiesandcrackscausedbyunevencoolingratesduetoirregularwallthickness,itisrequiredthatthecastingwallthicknessbeuniformoradoptagraduallytransitioningstructure.UnreasonableReasonablePartIIMachiningProcessStructurePARTIIMachiningProcessStructure///ChamferandFilletToremoveburrs,sharpedges,andfacilitateassembly,theendsofshaftsandholes(ortheintersectionsoffacesandsurfacesofparts)aretypicallymachinedintoachamfer.Topreventcrackscausedbystressconcentration,filletsareoftenappliedatshaftshoulders,creatingasmoothtransition.Whenthechamferorfilletdimensionsaresmall,theymay