機械形位公差的中文說明

1.1GeometricalProductsSpecificationsofWeldsI.BriefIntroductionofTolerancesofFormandPosition1.Byexistentialstates:theoreticalandactualfeatures2.Bystructuralfeatures:procentralfeatures3.Byposition:tolerancedfeaturesanddatums4.Byfunctionalrelations:singleandrelatedfeaturesTolerancesofFormandPositionstudiesgeometricalspecificationsofgeometricalcomponentsofapart,thatispoints,linesandsurfaces.11.2Symbolsforgeometricalcharacteristics21.3Tolerancedfeatures1.Toleranceframe（1）Therequirementsareshowninarectangularframewhichisdividedintotwoormorecompartments.Thesecompartmentscontain,fromlefttorightorfromuptodown,inthefollowingorderthesymbolforthegeometricalcharacteristic,thetolerancevalue,datum(nodatumfortolerancesofform)andaleaderline.

（2）Thetolerancevalueintheunitusedforlineardimensions:Thisvalueisprecededbythesymbol“”；orby“S”ifthetolerancezoneisspherical.Whenthetoleranceappliestomorethanonefeaturethisshallbeindicatedabovethetoleranceframebythenumberoffeaturesfollowedbythesymbol“×”.3

(3)Ifitisnecessarytospecifymorethanonegeometricalcharacteristicforafeature,therequirementsmaybegivenintoleranceframedoneundertheotherforconvenience.42.Theleaderlineandtolerancedfeatures

Thetoleranceframeshallbeconnectedtothetolerancedfeaturebyaleaderlinewithanarrowheadstartingfromeithersideoftheframeandperpendiculartotheframe.Leadingtothetolerancedfeature,theleaderlinecouldbendbutnotmorethantwice.Whenthetolerancereferstothelineorsurface,thearrowheadshallbeplacedontheoutlineofthefeatureoranextensionoftheoutline(butclearlyseparatedfromthedimensionline);thearrowheadmaybeplacedonareferencelineusingaleaderlinetopointtothesurface(seefollowingexamples).

5

Theleaderlineshallbeasanextensionofthedimensionlinewhenthetolerancereferstothemedianlineormediansurfaceorapointdefinedbythefeaturesodimensioned(seefollowingexamples).6

Individualtolerancezonesofthesamevalueappliedtoseveralseparatefeaturesmaybespecifiedinthefollowingway.73.Datums

Adatumrelatedtoatolerancedfeatureshallbedesignatedbyadatumletter.Acapitallettershallbeenclosedinadatumframeandconnectedtoafilledoropendatumtriangletoidentifythedatum(seethefollowingexample);thesameletterwhichdefinesthedatumshallalsobeindicatedinthetoleranceframe.Thereisnodifferenceinthemeaningbetweenafilledandanopendatumtriangle.8

Acommondatumestablishedbytwofeaturesisidentifiedbytwocapitallettersseparatedbyahyphen;whereadatumsystemisestablishedbytwoorthreefeatures,i.e.multipledatums,thecapitallettersforidentifyingthedatumsareindicatedinanorderofpriority,fromlefttoright,inseparatecompartments(seethefollowingexamples)。9Thedatumtrianglewiththedatumlettershallbeplacedontheoutlineofthefeatureoranextensionoftheoutline(butclearlyseparatedfromthedimensionline)whenthedatumisthelineorsurfaceshown;thedatumtrianglemaybeplacedonareferencelineusingaleaderlinetopointtothesurface.

Thedatumtrianglewiththedatumlettershallbeplacedasanextensionofthedimensionlinewhenthedatumistheaxisormedianplaneorapointdefinedbythefeaturesodimensioned(seethefollowingexamples).Ifthereisinsufficientspacefortwoarrowheads,oneofthemmaybereplacedbythedatumtriangle(seethefollowingexample).10

4.Theoreticallyexactdimensions(TED)

TEDaredimensionsdeterminingthetheoreticallyexactlocation,orientationorprofile(orangle).Theyarealsoindicatedbydimensionsoranglesenclosedinaframe.TEDshowanidealstatusoftolerancedfeaturesordatumsandthereforeshallnotbetoleranced(seethefollowingexamples).5.Restrictivespecificationsrestrictedvalue

arestrictedpartofafeature11121.4TolerancezonesAtolerancezonehasfourfeatures:form,dimension,locationanddirection.1.FormofatolerancezoneFormofatolerancezoneisanidealformlimitingthechangesoftolerancedfeatures.Itisdeterminedbytheidealformoftolerancedfeaturesandfeaturesofatolerance.Normalformsofatolerancezoneareshownasfollowings:132.Dimensionsoftolerancezones

Thewidthordiameterofanidealcontainedzone.

3.Directionoftolerancezones

Theorientationoftolerances.Asfarasorientationandlocationtolerancesareconcerned,thedirectionofatolerancezoneisindicatedbythearrowheadasapartoftheleaderlineconnectedwiththetoleranceframe.Thedirectionofaformtolerancezone,inaddition,dependsontheactualstatusofthetolerancedfeatures.Thedirectionsofleaderlinesofstraightnessandflatnesstolerancezonesarethesamebutthedirectionofthetolerancezonesaredifferent.144.Locationoftolerancezones

Thelocationoftolerancezonesrelativetothatofthetolerancefeatures.Therearetwokindsoflocations:fixedandfloatinglocations.Ifthelocationofatolerancezonechangesinaccordancewithchangesinforms,orientationsandlocationsoftolerancedfeatures,itisafloatingtolerancezone,otherwise,itisafixed.15 Thedifferencesinformsandlocationslimitingparts.Itisthealloweddeviationsinform,orientationandlocationoftheactualfeatures. Therearethreetypesoftolerances:form,orientationandlocationtolerances.2.1formtolerancesFormtolerancesincludestraightness,flatness,roundness,cylindricity,proofalineandproofasurfaceaswell.1.straightnesstolerance

Thedeviationsinformslimitingactuallines.Accordingtothefunctionsofparts,straightnesstolerancescouldbedividedintothreetypes：straightnesstolerancesofalineinasurface,ofalinewithspecifieddirectionandofalinewithnospecifieddirections.a.straightnesstolerancesofalineinasurface

Thetolerancezoneisthearealimitedbytwoparallelstraightlinesadistancetapart.

II.Tolerancesofformsandlocations16b.straightnesswithspecifieddirection

Thetolerancezoneisthearealimitedbytwoparallelsurfacesadistancetapart.

c.straightnesswithnospecifieddirectionIfthetolerancevalueisprecededbythesymbolΦ，thetolerancezoneislimitedbyacylinderofdiametert.

172.FlatnesstoleranceThedeviationsinformslimitingactualsurfacesandlimitingthestraightnesstolerancesofactualsurfaces.Thetolerancezoneisthearealimitedbytwoparallelsurfacesadistancetapart.183.Roundnesstolerance

Onetoleranceitemlimitingthedeviationofroundnessinsectionformsofactualparts.Thetolerancezoneisthearealimitedbytwoconcentriccircleswithadifferenceinradiioftinonecross-section.194.cylindricity

Onetoleranceitemlimitingthechangesofacylinder’sforms.Itcouldlimitthedeviationsofbothcross-sectionandlongitudinalsectionofacylinder.thetolerancezoneislimitedbytwocoaxialcylinderswithadifferenceinradiioft.Conclusions：Toleranceofformappliesonlytodeviationsinformsofsinglefeatureanddoesnotneedadatum,therefore,itisnotaffectedbyitsdirectionorlocation.Besides,astheiridealfeaturesarenotspecifiedbydimensions,thelocationofthetolerancezoneisfloating,thatis,itwillchangeinaccordancewiththeactualformsofparts.202.2Prozone

Aprobelongstoformorlocationtolerances.Whenadatumisneeded,itisaformtolerance,otherwise,itisalocationtolerance.Procanalsobedividedintotwotypes:proofalineandproofasurface.

1.Proofaline

Limitingproofplanecurvesorofthesectionsofcurvedsurfaces.Thetolerancezoneislimitedbytwolinesenvelopingcirclesofdiametert.212.Proofasurface

Limitingtheprocurvedsurfaces.Thetolerancezoneislimitedbytwosurfacesenvelopingsphereofdiametert,thecentersofwhicharesituatedonasurfacehavingthetheoreticallyezactgeometricalform(andidealposition).222.3LocationtolerancesAlocationtoleranceshowsthevariationsindirectionand/orlocationofafeatureasrelatedtoadatum.Locationtolerancescanalsobecategorizedintothreetypes:orientation,locationandrun-outtolerance.Orientationtolerance

Aorientationtoleranceshowstheallowedvariationindirectionofafeatureasrelatedtoadatum.Orientationtolerancesincludeparallelism,perpendicularity,andangularity,eachofwhichcouldbefurtherdividedintofourtypes:toleranceofalinerelatedtoadatumline,toleranceofalinerelatedtoadatumsurface,toleranceofasurfacerelatedtoadatumlineandtoleranceofasurfacerelatedtoadatumsurface.23①line-lineIftwolinesareinthesamespecifieddirection,theparallelismtolerancezoneislimitedbytwoparallelplanesadistancetapartandparalleltothedatum.a.Parallelism24

Iftwolinesareintwodifferentspecifieddirections,theparallelismtolerancezoneislimitedbyaquadrangular,thatis,twopairsofparallelplanesadistancet1andt2respectivelyapartandperpendiculartoeachother.Theplanesareparalleltothedatumaxis.

25Ifthetwolinesareinarbitrarydirections,theparallelismtolerancezoneislimitedbyacylinderofdiametert,paralleltothedatum.26②toleranceofalinerelatedtoadatumsurface

Thetolerancezoneislimitedbytwoparallelplanesadistancetapartandparalleltothedatumsurface.

③toleranceofasurfacerelatedtoadatumsurfaceThetolerancezoneislimitedbytwoparallelplanesadistancetapartandparalleltothedatumline.27

④toleranceofasurfacerelatedtothesurfaceThetolerancezoneislimitedbytwoparallelplanesadistancetapartandparalleltothedatumsurface.28b.perpendicularity

Perpendicularitytolerancelimitingtheverticalchangesoftolerancedfeaturesrelatedtothedatum.Thetolerancezonecouldbetwoparallelplanes,aquadrangular(twopairsofparallelplanesperpendiculartoeachother),acylinderandsoon.

①perpendicularitytoleranceofalinerelatedtoadatumlineThetolerancezoneislimitedbytwoparallelplanesadistancetapartandperpendiculartothedatumline.29Thelineandthesurfaceinthesamespecifieddirection—thetolerancezoneislimitedbytwoparallelplanesadistancetapartandperpendiculartothedatumsurface.②toleranceofalinerelatedtoadatumsurface30Thelineandthedatumsurfaceareintwodifferentdirections—thetolerancezoneislimitedbytwopairsofparallelplanesadistanceoft1andt2respectivelyapartandperpendiculartoeachother.Theselinesarealsoperpendiculartothedatumsurface.31Thelineandthedatumsurfaceareinarbitrarydirections—thetolerancezoneislimitedbyacylinderwithdiametertandperpendiculartothedatumsurface.32③toleranceofasurfacetoadatumlineThetolerancezoneislimitedbytwoparallelplanesadistancetapartandperpendiculartothedatumline.33④toleranceofasurfacerelatedtoadatumsurfaceThetolerancezoneislimitedbytwoparallelplanesadistancetapartandperpendiculartothedatumsurface.34c.AngularityAnangularitytolerancelimitstheangularvariationsofthetolerancedfeaturesinaspecifieddirectionasrelatedtoadatum.Thetolerancezonecouldbelimitedbytwoparallelplanes,aquadrangle(twopairsofparallelplanesperpendiculartoeachother),acylinderandsoon.Angularitytoleranceofasurfacerelatedtoadatumsurface—thetolerancezoneislimitedbytwoparallelplanedadistancetapartandinclinedataspecifiedangletothedatumsurface.Toleranceofasurfacerelatedtoadatumline—thetolerancezoneislimitedbytwoparallelplanesadistancetapartandinclinedataspecifiedangletothedatumline.35Conclusions:Orientationtolerancezonehasaspecifieddirectionasrelatedtothedatumbutitslocationisfloating.Itcouldlimitthedeviationsindirectionandformoftolerancedfeatures.Forexample,theparallelismtolerancecouldlimitboththeparalleldeviationoftolerancedfeaturesasrelatedtothedatumandtheflatnessdeviationoftolerancedfeatures.362.LocationtoleranceAlocationtoleranceshowstheallowedvariationsinlocationoftolerancedfeaturesasrelatedtothedatum.Thelocationtolerancezoneisanarealimitingthelocationvariationsoftolerancedfeaturesasrelatedtothedatum,andtherefore,itisspecifiedinlocation.

Locationtolerancesconsistofcoaxiality,symmetryandlocation.37a.CoaxialityCoaxialityisalocationtoleranceshowingwhethertheaxialoftolercancedfeaturesandthedatumaxialareinthesameaxial.Inotherwords,theideallocationoftheaxialoftolerancedfeaturesshouldbethesameasthatofthedatumaxial.Thetolerancezoneislimitedbyacylinderwithadiametertandtheaxialofwhichisthesameasthatofthedatum.

38b.Symmetry

symmetryisthetoleranceshowingwhetherthetolerancedfeatures(amedianplaneorcenterline)arecoplanarwiththedatum(amedianplaneorcenterline).Inotherwords,theidealpositionofthetolerancedfeaturesandthedatumshouldbecoplanar.Thetoleranceofasurfacerelatedtoadatumlineandthatrelatedtoadatumsurfacearethetwotypesofsymmetrytolerances.39

Showninthefollowingexampleisthesymmetrytoleranceofasurfacerelatedtoadatumsurface.Thetolerancezoneislimitedbytwoparallelplanesadistancetapartwhicharesymmetricallydisposedaboutthedatummedianplane.Theactualsurfaceshouldbecontainedbetweentwoparallelplanes0.08apartwhicharesymmetricallydisposedaboutthedatummedianplaneA.Shownintheaboveisthesymmetrytoleranceofasurfacerelatedtoadatumline.Thetolerancezoneislimitedbytwoparallelplanesadistancetapartwhicharesymmetricallydisposedaboutthedatumaxis.Themedianplaneofthekeyslotshownintheaboveshouldbecontainedbetweentwoparallelplanesadistance0.1mmapartwhicharesymmetricallydisposedabouttheplaneofthedatumaxis.40c.Locationtolerance

Alocationtoleranceshowsthedeviationsoftheactualpositionofthetolerancedfeaturesasrelatedtotheidealposition.Theidealpositioniscomprehensivelydeterminedbytheoreticallyexactdimensionanddatum.Thetolerancedfeaturesforalocationtolerancecouldbepoints,linesandsurfacesandtheformsofitszonemaybeacircle,asphere,acylinder,twoparallelplanesoraquadrangle(twopairsofparallelplaneswhichareperpendiculartoeachother).

Shownontheleftisthelocationtoleranceofaline.Itstolerancezoneislimitedbyacylinderofdiametert.TheaxialofthetolerancezoneshouldbeintheidealpositionwhichisfixedbytheoreticallyexactdimensionswithrespecttothedatumA,BandC.Theaxialoftheexamplepartshallbewithinacylindricalzoneofdiameter0.08,theaxialofwhichcoincideswiththetheoreticallyexactpositionoftheconsideredholewithrespecttodatumplanesC,BandA.41

Showninthefollowingexampleisthelocationtoleranceofasurface,whosezoneislimitedbytwoparallelplanesadistancetapartandsymmetricallydisposedaboutthetheoreticallyexactpositionfixedbyTEDwithrespecttothreedatums.Intheexample,theactualsurfaceshallbecontainedbetweentwoparallelplanes0.05apartthataresymmetricallydisposedaboutthetheoreticallyexactpositionofthesurface,withrespecttodatumplaneAanddatumaxisB.42Conclusions:ThelocationtolerancezoneisfixedbyTEDwithrespecttodatums,i.e.itspositionisspecifiedandfixed.Thelocationtolerancezonecouldlimitthepositionoftolerancedfeaturesandothertolerancesindirectionandform.Asshownintheaboveexample,neithertheflatnesstolerancenorangularitytoleranceoftheplanewillgoexceed0.05.433.Run-outtoleranceArun-outtolerance,definedaccordingtothedetectionmethods,showstheallowedvariationsofrunoutoftheactualsurfaceinthenormaldirectionwhilethetolerancedfeaturesarerotatingonthedatumaxis.Therunoutamountisdifferencebetweenthemaximunandminimumreadoutintheindicatingguage.Runouttolerancescouldbedividedintocircularrunoutandtotalrunouttolerancesinaccordancewithwhetherthemeasuringheadoftheindicatingguagemovesasrelatedtotheactualsurface.44Radialcircularrun-outtolerance

Thetolerancezoneislimitedwithinanycross-sectionperpendiculartothedatumaxisbytwoconcentriccircleswithadifferenceinradiioft,thecentersofwhichcoincidewiththedatum.a.CircularrunoutCircularrunouttoleranceisthemaximumallowedreadoutatanyextractedsurfaceindicatedinthenon-movableguagewhiletheextractedpartrotatesonthedatumaxis.Normally,run-outmeansthatpartmakesafullrotationonthedatumaxisandcouldalsolimitpartofthecircle.Circularrunouttolerancesappliestodifferentmeasuringpositionsandthereforetheycouldbefurtherdividedintoradial,axialandslantcircularrun-outtolerancesaccordingtodifferentmeasurementsurfaces.

45Axialcircularrun-outtolerancesThemeasuringdirectionofanaxialcircularrunouttoleranceisparalleltothedatumaxisandthemeasurementsectionisacylindricalsection,theaxisofwhichcoincideswiththatofthedatum.Itstolerancezoneislimitedtoanycylindricalsectionbytwocircleswithadistancetapartlyinginthecylindricalsection,theaxisofwhichcoincideswiththedatum.

46Slantcircularrun-outtolerances

Themeasuringdirectionofaslantcirc