联轴器强度计算公式.
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December19991312
3.2.9LineShaftCouplings Inordertoreducetheeffectofgalvanicactionbetweentwounlikematerials,lineshaftsectionssh allbeconnectedbyleft-
handthreadedcouplingsorkeywaycouplings,composedofamaterialsimilarorsuperiortothos eofthelineshafts.Couplingthreadsshallbenontaperedandtendtotightenduringpumpoperatio n.CalculationsshallbesubmittedtoFMApprovalsaspartofthedrawingreviewprocess.Them aximumcombinedshearstressinthecouplingshallnotexceed20percentofthetensileyieldstre ngthorbemorethan12percentoftheultimatetensilestrengthofthecouplingmaterial.Thefollo wingformulaforcalculatingthecombinedshearstressistakenfromANSI/AWWAE101,‘‘A WWAStandardforVerticalTurbinePumps–LineShaftandSubmersibleTypes’’. EnglishS=Metric√2f
π(D2-d2)2+321,000P
N(D3-d3)2S=1×106√2f
π(D2-d2)2+46,835P
N(D3-d3)2
Where:S–combinedshearstress,psi(kPa)
f–
totalaxialthrust,includingtheweightoftheshaftandallrotatingpartssupportedbyit,pounds(n ewtons)
N–ratedspeed,r/min
D–outsidediameterofthecoupling,in.(mm)
d–insidediameterofthecouplingattherootofthethreads,in.(mm)
P–power,horsepower(watts)
3.2.10ShaftSeals Theshaftsealshalladequatelysafeguardagainstexcessivewaterleakageoutofthepumpwhens uctionpressureisaboveatmospheric.
Note:Mechanicalseals,intheirpresentstateofdesign,arenotacceptableduetopotentialforda mageduetostickingofthesliding
surfacesafterprolongedperiodsofnon-operation,andotherunfavorablewearcharacteristics.
3.2.11LineShaftBearings
A.WaterLubricatedPumps Inordertoinsureadequatecenteringofthelineshaftwithinthecolumn,bearingsshallbespaced nomorethan10ft(3.1m)apart.Thesebearingsshallbelubricatedbythepumpedwater.
B.OilLubricatedPumps
Thelineshaftbearingswhichareanintegralpartofthecouplingsfortheshaft-enclosingtubeshallbespacednomorethan5ft(1.5m)apart.Thesebearingsshallbelubricatedb ytheoilwithintheshaft-
enclosingtube.CalculationsshallbesubmittedtoFMApprovalsaspartofthedrawingreviewpr ocess.
Toprovideadequatedurability,anti-frictionbearingsshallhavethefollowingfeatures: •Aminimumcalculatedliferatingofnotlessthan5000hoursatmaximumload;•Arrangementtofloataxiallyo noneorbothends;and, •Lubricationbythepumpedwaterinopenlineshafts,orlubricationbytheoilwithintheenclosed lineshafts.FMAPPROVALS9