AGMA-91FTM10-1991.pdf
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1、91 FTM 10 v DynamicMeasurementsof Gear Tooth Frictionand Load by: B. Rebbechi,F. B. Oswald and D. P. Townsend NASA,Lewis ResearchCenter _A V , AmericanGear ManufacturersAssociation :_TECHNICAL PAPER Copyright American Gear Manufacturers Association Provided by IHS under license with AGMA Licensee=IH
2、S Employees/1111111001, User=Wing, Bernie Not for Resale, 04/18/2007 11:53:51 MDTNo reproduction or networking permitted without license from IHS -,-,- Dynamic Measurementsof Gear Tooth Friction and Load B. Rebbechi, F. B. Oswald and D. Townsend NASA, Lewis Research Center TheStatements andopinionsc
3、ontainedherein arethoseoftheauthorandshouldnotbeconstruedasan officialactionor opinion ofthe American GearManufacturers Association. ABSTRACT: A program to experimentallyand theoretically study fundamentalmechanisms of gear dynamic behavior is being conductedat the NASA Lewis Research Centerin suppo
4、rtof ajoint research program between NASA and the U. S. Army. Thispaperpresentstheresults ofdynamictooth-fillet straingage measurementsfromtheNASA gear-noiserig, andit inlroduces atechniqueforusingthese measurementsto separate thenormalandtangential(friction) components of the load at the tooth cont
5、act-_- Copyright 1991 American Gear ManufacturersAssociation 1500 King Slreet, Suite 201 Alexandria,Virginia, 22314 October,1991 ISBN:1-55589-607-3 Copyright American Gear Manufacturers Association Provided by IHS under license with AGMA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for R
6、esale, 04/18/2007 11:53:51 MDTNo reproduction or networking permitted without license from IHS -,-,- DynamicMeasurementsofGearToothFriction andLoad BrianRebbechl,FredB.Oswald,and DennisP.Townsend NationalAeronauticsandSpace Administration LewisResearchCenter Cleveland,Ohio44135 i.INTRODUCTIONproblem
7、s.AndersonandLowenthal4 com- putedoveralllossesduetofrictionand _Thedynamicforcesatthepointoffoundgoodagreementbetweentheoretical toothcontactareofconsiderableinterestpredictionsandexperimentaldata.Krantz tothedesignersofhigh-speed,light-andHandschuh5appliedasimilartech- weightgearing.Accuratepredic
8、tionoftheniquetoanepicyclicgearrig,obtaining dynamicloadscanassistinminimizingthegoodcorrelationatlowoiltemperatures, sizeandweightofatransmission.Inabutpoorercorrelationathigheroiltem- helicopterapplication,wherethetransmis-peratures.However,thistechniquecannot sionisasignificantfractionofvehiclede
9、tectthevariationinfrictionduringthe weight,suchareductionwouldbeanimpor-toothengagementcycle.Thereisalsothe tantfactorinoverallvehicleperformance,problemofseparatingthepowerlossdueto Aprogramtoexperimentallyandtheo-geartoothfrictionfrompowerlossesdue reticallystudyfundamentalmechanismsoftoothersourc
10、essuchasbearings,windage, geardynamicbehaviorisbeingundertakenandsoforth. attheNASALewisResearchCenterinsup-Extensivemeasurementsoflubrication portofajointresearchprogrambetweenconditionsatasliding-rollingcontact NASAandtheU.S.Army.Thispaperpre-havebeencarriedoutondiskmachines6 . sentstheresultsofdy
11、namictooth-filletTheseexperimentsareofconsiderablevalue straingagemeasurementsfromtheNASAinconfirmingtheexistenceofelastohydro- gear-noiserig,anditintroducesatech-dynamiclubricationandinidentifyingthe niqueforusingthesemeasurementstoseparateregimesoflubricationthatpre- separatethenormalandtangential
12、vailunderthevariousslide-to-roll (friction)componentsoftheloadattheratios.However,theusefulnessofthe toothcontact.Resolutionofthecontactmodesofbehaviorandfrictioncoefficients forceisdesirableforseveralreasons,inpredictinglubricationconditionsatan Twoofthesereasonsarethefollowing:actualtoothcontact,w
13、herethedegreeof (I)Aprimaryoutputofanalyticalslidingchangesthroughoutthetooth modelsofgeardynamicbehavioristypi-engagementcycle(typicalduration, callythenormalforceatthepointof250_sec),needstobeverified.Inthis contact(e.g.,Iand2).shortperiodoftime,largechangesoccur (2)Themeasurementofdynamicinthelub
14、ricanttemperature,shear,and frictionofmeshinggearsdoesnotappearviscosityatpressuresupto1.4GPa tohaveyetbeencarriedoutsuccessfully.(200000ibf-in._).Dyson7reported Aninterestingtrialwascarriedouttemperaturesupto400Candoscillatory AbyBenedictandKelly3,butitwasdis-shearratesuptol0 Tsec -IThesecon- conti
15、nuedbecauseofdynamicresponseditionscannotreadilybeproducedoutside ofanactualtoothmesh. VisitingscientistfromAustralian AeronauticalResearchLaboratory. Copyright American Gear Manufacturers Association Provided by IHS under license with AGMA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not fo
16、r Resale, 04/18/2007 11:53:51 MDTNo reproduction or networking permitted without license from IHS -,-,- Frictionatthetoothcontactistooth-rootfilletsonboththeloaded importantfordeterminingnotonlypower(tensile)andunloaded(compression)side lossandefficiency,butalsoforunder-oftwoadjacentteethontheoutput
17、 standinggear-toothscoringandwear.An(driven)gear(Fig.4).Tomeasuremaximum importantparameterinscoringisthefric-toothbendingstress,thegageswereplaced_ tioncoefficient3.Frictiongreatlyatthe30 tangencylocation9. affectstheheatinputtothelubricantStraingagesignalswereconditioned whenslidingvelocitiesarehi
18、gh.bytwomethods:forstaticcalibrationand Thisreportpresentsdynamic,gear-measurement,astraingage(Wheatstone) toothstrainmeasurementsfromlow-contact-bridgewasused;fordynamicmeasurements, ratiospurgearstestedintheNASAgear-thestraingageswereconnectedviaaslip- noiserlg.Thetechniqueusedtoconvertringassembl
19、ytoasetofconstant-current thesestrainmeasurementsintonormalandstraingageamplifiers. tangential(friction)toothloadsisA4-channel,14-bitdigitaldata described.Plotsofnormalandtangentialacquisitionsystemwasusedtorecordthe forces,forbothstaticanddynamiccondi-dynamicstraindata.Sampleratesof20to tions,arepr
20、esentedforarepresentative50kHzperchannelwereused,dependingon rangeofloadsandspeeds.Thenormaltestgearspeed. forceanddynamicstraindatahavebeenAnopticalencoderwasmountedonthe usedtoverifyageardynamicscodeininputshafttomeasurerollangleandhence anotherrelatedreport8.determineloadlocation;thepositionof th
21、eencoderwasadjustedsoitwouldpro- 2.APPARATUSduce1pulse/revolutionataknownroll angle. 2.1TestFacility 3.TESTPROCEDURE ThesetestswereconductedintheNASA Lewisgear-noiserig(Fig.i).Thisrig3.1Calibration comprisesasimplegearboxpoweredbya 150-kW(200-hp)variablespeedelectricCalibrationofthestraingagesonthe
22、motor,withaneddy-currentdynamometerinstrumented(driven)gearwasconductedto thatloadstheoutputshaft.Thegearboxprovideamatrixofstrainoutputversus canbeoperatedatspeedsupto6000rpm.appliedload.Beforecommencingthestrain Therigwasbuilttocarryoutfundamentalgagecalibration,thegearsweredemagne- studiesofgearn
23、oiseandofdynamictized.Thisdemagnetizationreducedthe behaviorofgearsystems.ItwasdesignedapparentstrainresultingfromthegagesA toallowtestingofvariousconfigurationsmovingthroughthemagneticfieldofthe ofgears,bearings,dampers,andsupports,adjacentgear.Atnormalgearoperating Apoly-Vbeltdriveservedasaspeedsp
24、eeds,magneticeffectscaninducean increaserbetweenthemotorandinputerrorsignalinthegage. shaft.AsoftcouplingwasinstalledonForcalibration,theinstrumentedgear theinputshafttoreduceinputtorquewasmeshedwithaspecialgearwhoseadja- fluctuationscausedbyanonuniformityofcentteethhadbeengroundaway;thisper- thebel
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