机械形位公差的中文说明

1.1GeometricalProductsSpecificationsofWeldsI.BriefIntroductionofTolerancesofFormandPosition1.Byexistentialstates:theoreticalandactualfeatures2.Bystructuralfeatures:profileandcentralfeatures3.Byposition:tolerancedfeaturesanddatums4.Byfunctionalrelations:singleandrelatedfeaturesTolerancesofFormandPositionstudiesgeometricalspecificationsofgeometricalcomponentsofapart,thatispoints,linesandsurfaces.ToleranceCharacteristicsSymbolsDatumneededFormFormStraightnessNoFlatnessNoRoundnessNoCylindricityNoFormorlocationProfileProfileanylineYesorNoProfileanysurfaceYesorNoLocationOrientationParallelismYesPerpendicularityYesAngularityYesLocationPositionYesorNoConcentricity/CoaxialityYesSymmetryYesRun-outCircularrun-outYesTotalrun-outYes1.2Symbolsforgeometricalcharacteristics1.3Tolerancedfeatures1.Toleranceframe（1）Therequirementsareshowninarectangularframewhichisdividedintotwoormorecompartments.Thesecompartmentscontain,fromlefttorightorfromuptodown,inthefollowingorderthesymbolforthegeometricalcharacteristic,thetolerancevalue,datum(nodatumfortolerancesofform)andaleaderline.（2）Thetolerancevalueintheunitusedforlineardimensions:Thisvalueisprecededbythesymbol“”；orby“S”ifthetolerancezoneisspherical.Whenthetoleranceappliestomorethanonefeaturethisshallbeindicatedabovethetoleranceframebythenumberoffeaturesfollowedbythesymbol“×”.(3)Ifitisnecessarytospecifymorethanonegeometricalcharacteristicforafeature,therequirementsmaybegivenintoleranceframedoneundertheotherforconvenience.2.TheleaderlineandtolerancedfeaturesThetoleranceframeshallbeconnectedtothetolerancedfeaturebyaleaderlinewithanarrowheadstartingfromeithersideoftheframeandperpendiculartotheframe.Leadingtothetolerancedfeature,theleaderlinecouldbendbutnotmorethantwice.Whenthetolerancereferstothelineorsurface,thearrowheadshallbeplacedontheoutlineofthefeatureoranextensionoftheoutline(butclearlyseparatedfromthedimensionline);thearrowheadmaybeplacedonareferencelineusingaleaderlinetopointtothesurface(seefollowingexamples).Theleaderlineshallbeasanextensionofthedimensionlinewhenthetolerancereferstothemedianlineormediansurfaceorapointdefinedbythefeaturesodimensioned(seefollowingexamples).Individualtolerancezonesofthesamevalueappliedtoseveralseparatefeaturesmaybespecifiedinthefollowingway.3.DatumsAdatumrelatedtoatolerancedfeatureshallbedesignatedbyadatumletter.Acapitallettershallbeenclosedinadatumframeandconnectedtoafilledoropendatumtriangletoidentifythedatum(seethefollowingexample);thesameletterwhichdefinesthedatumshallalsobeindicatedinthetoleranceframe.Thereisnodifferenceinthemeaningbetweenafilledandanopendatumtriangle.Acommondatumestablishedbytwofeaturesisidentifiedbytwocapitallettersseparatedbyahyphen;whereadatumsystemisestablishedbytwoorthreefeatures,i.e.multipledatums,thecapitallettersforidentifyingthedatumsareindicatedinanorderofpriority,fromlefttoright,inseparatecompartments(seethefollowingexamples)。Thedatumtrianglewiththedatumlettershallbeplacedontheoutlineofthefeatureoranextensionoftheoutline(butclearlyseparatedfromthedimensionline)whenthedatumisthelineorsurfaceshown;thedatumtrianglemaybeplacedonareferencelineusingaleaderlinetopointtothesurface.Thedatumtrianglewiththedatumlettershallbeplacedasanextensionofthedimensionlinewhenthedatumistheaxisormedianplaneorapointdefinedbythefeaturesodimensioned(seethefollowingexamples).Ifthereisinsufficientspacefortwoarrowheads,oneofthemmaybereplacedbythedatumtriangle(seethefollowingexample).4.Theoreticallyexactdimensions(TED)TEDaredimensionsdeterminingthetheoreticallyexactlocation,orientationorprofile(orangle).Theyarealsoindicatedbydimensionsoranglesenclosedinaframe.TEDshowanidealstatusoftolerancedfeaturesordatumsandthereforeshallnotbetoleranced(seethefollowingexamples).5.Restrictivespecificationsrestrictedvaluearestrictedpartofafeature1.4TolerancezonesAtolerancezonehasfourfeatures:form,dimension,locationanddirection.1.FormofatolerancezoneFormofatolerancezoneisanidealformlimitingthechangesoftolerancedfeatures.Itisdeterminedbytheidealformoftolerancedfeaturesandfeaturesofatolerance.Normalformsofatolerancezoneareshownasfollowings:2.DimensionsoftolerancezonesThewidthordiameterofanidealcontainedzone.3.DirectionoftolerancezonesTheorientationoftolerances.Asfarasorientationandlocationtolerancesareconcerned,thedirectionofatolerancezoneisindicatedbythearrowheadasapartoftheleaderlineconnectedwiththetoleranceframe.Thedirectionofaformtolerancezone,inaddition,dependsontheactualstatusofthetolerancedfeatures.Thedirectionsofleaderlinesofstraightnessandflatnesstolerancezonesarethesamebutthedirectionofthetolerancezonesaredifferent.4.LocationoftolerancezonesThelocationoftolerancezonesrelativetothatofthetolerancefeatures.Therearetwokindsoflocations:fixedandfloatinglocations.Ifthelocationofatolerancezonechangesinaccordancewithchangesinforms,orientationsandlocationsoftolerancedfeatures,itisafloatingtolerancezone,otherwise,itisafixed.Thedifferencesinformsandlocationslimitingparts.Itisthealloweddeviationsinform,orientationandlocationoftheactualfeatures.Therearethreetypeso