公差与互换性国际标准07Chapter 4 roughness.docx
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公差与互换性国际标准07Chapter4roughness
Chapter4
Roughness
4.1Generaltermsanddefinitions
•surfaceprofile:
Profilethatresultsfromtheintersectionoftherealsurfacebyaspecifiedplane.
•samplinglengthlr:
LengthinthedirectionoftheX-axisusedforidentifyingtheirregularitiescharacterizingtheprofileunderevaluation.
•evaluationlengthln:
LengthinthedirectionoftheX-axisusedforassessingtheprofileunderevaluation.Ingeneral,evaluationlengthequalfivesamplinglength.
•profilepeak:
Anoutwardlydirected(frommaterialtosurroundingmedium)portionoftheassessedprofileconnectingtwoadjacentpointsoftheintersectionoftheprofilewiththeX-axis.
•profilevalley:
Aninwardlydirected(fromsurroundingmediumtomaterial)portionoftheassessedprofileconnectingtwoadjacentpointsoftheintersectionoftheprofilewiththeX-axis.
•ordinatevalueZ(x):
Heightoftheassessedprofileatanypositionx.
•profilepeakheightZp:
DistancebetweentheX-axisandthehighestpointoftheprofilepeak.RpisthelargestprofilepeakheightZpwithinasamplinglength.
•profilevalleydepthZv:
DistancebetweentheX-axisandthelowestpointoftheprofilevalley.RvisthelargestprofilevalleydepthZvwithinasamplinglength.
•profileelementwidthXs:
LengthoftheX-axissegmentintersectingwiththeprofileelement.
4.2Evaluationparameter
Amplitudeparameters
•ArithmeticalmeandeviationoftheassessedprofileRa:
ArithmeticmeanoftheabsoluteordinatevaluesZ(x)withinsamplinglength.
•MaximumheightofprofileRz:
SumofheightofthelargestprofilepeakheightZpandthelargestprofilevalleydepthZvwithinasamplinglength.
Spacingparameters
•MeanwidthoftheprofileelementsRSm:
MeanvalueoftheprofileelementwidthsXswithinasamplinglength.
4.3Graphicalsymbolsfortheindicationofsurfacetexture
Basicgraphicalsymbol
Thebasicgraphicalsymbolshallconsistoftwostraightlinesofunequallengthinclinedatapproximately60°tothelinerepresentingtheconsideredsurface,asshowninFigure4-1.ThebasicgraphicalsymbolinFigure4-1shouldnotbeusedalone(withoutcomplementaryinformation).
Expandedgraphicalsymbols
•Removalofmaterialrequired:
Ifremovalofmaterial—forexample,bymachining—isrequiredforobtainingthespecifiedsurface,abarshallbeaddedtothebasicgraphicalsymbol,asshowninFigure4-2.TheexpandedgraphicalsymbolinFigure4-2shouldnotbeusedalone(withoutcomplementaryinformation).
•Removalofmaterialnotpermitted:
Ifremovalofmaterialisnotpermittedforobtainingthespecifiedsurface,acircleshallbeaddedtothebasicgraphicalsymbol,asshowninFigure4-3.
Completegraphicalsymbol
•Whencomplementaryrequirementsforsurfacetexturecharacteristicshavetobeindicated,alineshallbeaddedtothelongerarmofanyofthegraphicalsymbolsillustratedinFigures4-1to4-3,asshowninFigure4-4.
•Foruseinthewrittentextof—forexample,reportsorcontracts—thetextualindicationforFigure4-4,a)isAPA1),forb)itisMRR2)andforc)NMR3).
Marks:
✧Anyprocessallowed.
✧Materialremovalrequired.
✧Nomaterialremoved.
4.4Compositionofcompletegraphicalsymbolforsurfacetexture
General
Inordertoensurethatasurfacetexturerequirementisunambiguous,itmaybenecessary,inadditiontotheindicationofbothasurfacetextureparameteranditsnumericalvalue,tospecifyadditionalrequirements(e.g.transmissionbandorsamplinglength,manufacturingprocess,surfacelayanditsorientationandpossiblemachiningallowances).Itmaybenecessarytosetuprequirementsforseveraldifferentsurfacetextureparametersinorderthatthesurfacerequirementsensureunambiguousfunctionalpropertiesofthesurface.
Rulesforcomparisonofthemeasuredvalueswiththetolerancelimits
•Thesurfacetextureoftheworkpieceunderinspectioncanappearhomogeneousorbequitedifferentovervariousareas.
•Thiscanbeseenbyvisualexaminationofthesurface.
•Incaseswherethesurfacetextureappearshomogeneous,parametervaluesdeterminedovertheentiresurfaceshallbeusedforcomparisonwiththerequirementsspecifiedonthedrawingsorinthetechnicalproductdocumentation.
•Ifthereareseparateareaswithobviouslydifferentsurfacetexture,theparametervalueswhicharedeterminedoneachareashallbeusedseparatelyforcomparisonwiththerequirementsspecifiedonthedrawingsorinthetechnicalproductdocumentation.
•Forrequirementsspecifiedbytheupperlimitoftheparameter,thoseseparateareasofthesurfaceshallbeusedwhichappeartohavethemaximumparametervalue.
The16%-rule
•Forrequirementsspecifiedbytheupperlimitofaparameter,thesurfaceisconsideredacceptableifnotmorethan16%ofallthemeasuredvaluesoftheselectedparameter,baseduponanevaluationlength,exceedthevaluespecifiedonthedrawingsorinthetechnicalproductdocumentation.
•Forrequirementsspecifiedbythelowerlimitofasurfaceparameter,thesurfaceisconsideredacceptableifnotmorethan16%ofallthemeasuredvaluesoftheselectedparameter,baseduponanevaluationlength,arelessthanthevaluespecifiedonthedrawingsorinthetechnicalproductdocumentation.
•Todesignatetheupperandthelowerlimitsoftheparameter,thesymboloftheparametershallbeusedwithoutthe“max.”index.
Themax.-rule
•Forrequirementsspecifiedbythemaximumvalueoftheparameterduringinspection,noneofthemeasuredvaluesoftheparameterovertheentiresurfaceunderinspectionshallexceedthevaluespecifiedonthedrawingsorinthetechnicalproductdocumentation.
•Todesignatethemaximumpermissiblevalueoftheparameter,the“max.”indexhastobeaddedtothesymboloftheparameter(forexampleRz1max.).
Positionofcomplementarysurfacetexturerequirements
•ThemandatorypositionsofthevarioussurfacetexturerequirementsinthecompletegraphicalsymbolareshowninFigure4-5.
•Thecomplementarysurfacetexturerequirementsintheformof
—surfacetextureparameters,
—numericalvalues,and
—transmissionband/samplinglength,
shallbelocatedatthespecificpositionsinthecompletegraphicalsymbolinaccordancewiththefollowing.
a)Positiona—Singlesurfacetexturerequirement
Indicatethesurfacetextureparameterdesignation,thenumericallimitvalueandthetransmissionband/samplinglength.Toavoidmisinterpretation,adoublespace(doubleblank)shallbeinsertedbetweentheparameterdesignationandthelimitvalue.
Generally,thetransmissionbandorsamplinglengthshallbeindicatedfollowedbyanobliquestroke(/),followedbythesurfacetextureparameterdesignation,followedbyitsnumericalvalueusingonetextstring.
Example1
0.0025-0.8/Rz6.8(examplewithtransmissionbandindicated)
Example2
-0.8/Rz6.8(examplewithonlysamplinglengthindicated)
Especiallyforthemotifmethod,thetransmissionbandshallbeindicated,followedbyanobliquestroke(/),followedbythevalueoftheevaluationlength,followedbyanotherobliquestroke,followedbythesurfacetextureparameterdesignation,followedbyitsnumericalvalue.
b)Positionaandb—Twoormoresurfacetexturerequirements
Indicatethefirstsurfacetexturerequirementatposition“a”asina).Indicatethesecondsurfacetexturerequirementatposition“b”.Ifathirdrequirementormoreistobeindicated,thegraphicalsymbolistobeenlargedaccordinglyintheverticaldirection,tomakeroomformorelines.Theposition“a”and“b”aretobemovedupwardswhenthesymbolisenlarged.
c)Positionc—Manufacturingmethod
Indicatethemanufacturingmethod,treatment,coatingsorotherrequirementsforthemanufacturingprocessetc.Toproducethesurface,forexample,turned,ground,plated.
Thesurfacetextureparametervalueofanactualsurfaceisstronglyinfluencedbythedetailedformoftheprofilecurve.Aparameterdesignation,parametervalueandtransmissionband—indicatedsolelyasasurfacetexturerequirement—donotthereforenecessarilyresultinanunambiguousfunctionofthesurface.Itisconsequentlynecessaryinalmostallcasestostatethemanufacturingprocess,asthisprocesstosomeextentresultsinaparticulardetailedformoftheprofilecurve.
Theremayalsobeotherreasonsforfindingitappropriatetoindicatetheprocess.
ThemanufacturingprocessofthespecifiedsurfacecanbepresentedastextandaddedtothecompletesymbolasshowninFigures4-6and4-7.
✧Positiond—Surfacelayandorientation
Indicatethesymboloftherequiredsurfacelayandtheorientation,ifany,ofthesurfacelay,forexample,“=”,“X”,“M”.
Thesurfacelayanddirectionofthelayemanatingfromthemanufacturingprocess(e.g.tracesleftbytools)maybeindicatedinthecompletesymbolbyusingthesymbolsshowninTable4-1andillustratedbytheexampleinFigure4-8.Theindicationofsurfacelaybythedefinedsymbols(e.g.theperpendicularitysymbolinFigure4-8)isnotapplicabletotextualindications.
Thedirectionoflayisthedirectionoftheprevailingsurfacepattern,whichisusuallydeterminedbythemanufacturingprocessused.
ThesymbolsinTable4.1indicatethelayanddirectionoflayinrelationtothedrawingplanecontainingthesurfacetexturerequirement.
Table4.1Indicationofsurfacelay
Graphical
symbol
Interpretationandexample
Paralleltoplaneofprojectionofviewinwhichsymbolisused
Perpendiculartoplaneofprojectionofviewinwhichsymbolisused
X
Crossedintwoobliquedirectionsrelativetoplaneofprojectionofviewinwhichs