StabilizationofhighfrequencychattervibrationinfneboringbyfrictiondamperEvitadhi*,TetsutaroHoshiAbstracFritondamperhasbeenfoundsuccesfultopreventhighfrequencychateroccurringatmorethan10,000Hz,andcusingproblmofrducdtoollinineboringopeation.Thenewdamperischarteridbysimplestructurethaconsistofadditionalmstcdtohemainvibratingstucturewithmalpicofpermanentmgnet.TheprincpleisstrightforrdinwhichCoulombndvisousfitonsdisipatevibrationenergyatheinteacbetethedamperaminbratingstructure.Thedamperdsnotuning,andisftiveathighfrequency.Thepaperfistntoducsatypicaldesignofthefrictondamperwithexpeimntalproofbycuttingteofiteftiveneinelimnatingthehighfequencychatrinfneboring,andsurinormaltoollieofthecuttidge.Toreticalandxperimentalnalysesrintroducedforunderstndingtfundamentalprincplndchartistcofthenewdampe.Thenewdampeiefctiveorboringtools,whichvibrateatfequencymorethan5,000Hz.Kywords:KKKHighfrequencychater；Fictondamper；Fineboring.1.IntuctoApreviousstudyreportdfineboringtoolsexhibitingchaterathighfrequency,morethan10,000Hz.Thefquencywasirtdentifdromthetmkltonthesurfac,thefurtherconfirmedincuttingtebydirectmasuremntusingthelaserdisplacemntmetr.Thatwasfoundatributabltobendingnaturalvibrationoftboringtool,slf-xcitedbycuttingprocesdynamicsthaincludetheregenertiveefct,heimaginarypartctofinnermodulation,andX-YLooping.Prventionofsuchhatrvibrtionsthetagetthepresnttudy.Efectivehatrpreventionduringcuttingoperationsmaybeachievedbyincreasingthedampingapaityofcuttingtoolsystem.Dampicpaitsgenerthrough(i)mco-lipatcertinnterfsincludedintheoolsystem,(i)slipathegrainboundarywithina1vibratingbodybymaterildamping(internalfricton),(i)frictonatninterfacbetwentheminvitindthemperstuctur.Studiesonvaiouskindofdampetoprventchaterbration,atoimprovetabilityofboringtoolorothercuttingoperationhabeenaidoutbymnyresarches.Prctialtypeofdampehavebeenconventionalyeitherdynamicorimpactdamper.Dynamidamperconsistofadditionalspring-masub-systm,andneedstuningofnaturalfrequencyofthesub-ystemtomchthaofthemintructure.Thedynamicdamperisusualdesignedtoincludenergydisipatonbyeitslidingorinternalfritonofthespringmateril.Impactdampeconsitofoneormoffremovibodies,andtincplmchanismistodisipatenergybytheimpactmngbodywithhemainstructure.Impatdampernedscrtainvelocityoeftivelyfunction,thuscannotbeppliedtoupprsvibrationtlowfrequency.Ahybriddesignofdynamicandimpatdampershasbeenrportedrcntly,andoundtobeefctivetouppresthelowfrequencyvibration.Itheprstudy,thedamperisrquirdtbefctiveatishighs10,000Hz,andithouldbedesignedwithinsizelimtaionoftheboringtooltoacommdatespaceforsetingtheoolinsert,chippocketandthedamperitself.Itisalprefrblthathedampernedsnotuning.Thedamperproposedintprenttudyconsitofapiceofmasatchedtohemainstructurebymanentmagnet.Tobjectiveoftheprsnttudyistonalyzethefectivenesandcharateristcoftheproposddamperineveingchatervibrationthaocurthighfrequency.oachievetheobjcti,uttitshavebeenconductedinboringoperationanaloguestonehavinghighfrequencyctrproblmitheplant,swelstheoreticalndexperimentalnalysesofnegydisipatonoftheoposeddamper.2.BongtostdantheproedaprstuceTheboringtoolunderstudythaoriginalyhaproblemofhighfrquencychaterconsitofa13mmdiametand20mmlongcantilevrdstlbarintegralwithabasflange.Amaldimetrhol,5.5mm,isprepardthendofthetoacommdatthedampermsofwhichdiametrmaybe5mmorls.Tpositontholeislectdinradilorientationom1,becusthehighfrequencyvibratiduetoX-Yloopinghasbeknowntooccurdominantlyintorientationom2asdepictedWhentoolisrotatedinboringoperation,thedamperispushedtohewloftheholbytcentifugalforc,butisfretomoveintorientationoftvibrationom2.Acapisprovidedtoprotethedampeomchipsremovedduringtheopertion.Thefctivenesoftdampehasbeentsedfortheoolashownithefigure,as2welasotherboringtoolsthavebeenprparedforcomparison.Oneoftcompariontoolshathesamdiamtr13mm,butextnded10mmbeyondthecuttingedge,andgeneratectervibrtiontbout5,000Hz.Othercomparisonsare16mmdiamtrcntilevetypeboringtools,deignedwithgreatrlength(L)todimt(D)ratiosthaexhibithatratlowerfquencie.Bsictructureofthenewictondamperisthecombinationofamsandpermanentmagnet,whihanchorstmastohemaintuctureonafltsurfceparletohediectionofvibration.Themgnetmybeeitrintegralorspartdwithhemas.Athirdmmber,aspacer,mybeinsertdtwnthepemnemgnetandtmintructurewhosepurposeitoontolmagnitudeofmagneticforce.Efctivenesofthefrictondampersinsuppresinghighfrequencyhatersbenvaluated.3.MthodxpinTvalidatehefectivenesofthedamperinviewofcontrollingthechater,andtoasurenormaltoolwarndurfaceroughnesgeneratd,uttitesvebenpeformedwithhe13mmdimetboringtoolotateditinproductionit.Inthiscae,theboringtoolismountedonthemainspindleofhorizontalmchiningcentrviatingadwhosefunctiontoadjustrdilpositontheooltipforautomtiontoloftheholediametrinproduction.Ringtypeworkpiecshavebeenprparedwhoseinnersurfaceistobemachinedbytherotatiboritool.RingsarmdeofSCM420Haloytel,hardenedt313to332Brinnelhadnesith25mmoutedimter,14.720.05mminnerdiamt,and15mmlength.Amilngchuckclampstheringonaspecialydesignedfixturewithsufficentstifnes.Thestndardonditiforcuttingtesieto130m/mincuttingped,0.03mm/revfedrate,0.14mmdepthof,andusinocuttingfluid.Anetiedgeisprpadforchstofcuttingtesinwhichorkpiesareontinuouslymachid.Thecuttingtesirepeatdwieforachboringtoolsystmwithndithoutthedamper.oolinsrtmarilusfortheboringtoolisTCermtnon-coated,ithaxilrakengle-5,radilkengle-15,andnoseradius0.4mm.Formsuringvibrationofthe16mmdiametrtool,anothersetupwasprepardwithhetoolheldtaionary,ndusedtomachineoutsurfceoftotatingriorkpic.Inthissetup,toolisclampebymilnghucktagedonabasepltonthemachinetableofverticalmhiningentr.Theriworkpiecismountendrotatedbytmspindl.34.Analysiofrictondamperchanism4.1TheoreticalnalysisDuringthedevelopmentofchater,oncethevibrationreachesertainthresholdamplitude,tdamperwilstarliding,trforintroducingfitontheintrfacebetwenthedampermasndthemintucture.Theictondisipateshevibratienegy,ndpreventthechaterfomgrowingbeyondthreholdamplitude.4.2ExperimentalnalysisInordetoscertainvalidityofthewotheoreticalmodelsasumingCoulombandviscousfrictonpetively,vibrationaminstructuremlhabeenmonitoredwithawithoutthedamrmastched,ndexcitdextnalybyanelctro-dynamicxcitr.cantileverdstelbem16mmdiamtr,havingsimlarcuttingdgedesignithheoriginalboringtooland170mmlength,hasbeenusdtheminstructurewhosecondderbendimodewsxcitdaround5,700Hzfrequency.Thevibrationthendofthebeamisdetecdbymicroizecleomtrpickup.Adamperwithnintegralmgnetistcdontopofthemainstucturvialnedanddriedntfaceslsoildinterfac.Rndomexcitaonisfrtpplietoideiythenaturalfrequencyoftheminstructure.ThensinusoidalitiaidatvariablemplitudeoftheinputdynamicforcFatfrequencyZfinelytunedroundthenatu