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外文翻译切削刀具.doc

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外文翻译切削刀具.doc

英文原文CUTTINGTOOLSWhenselectingcuttingtoolsforajob,thefirstthingtoconsideriswhattypeofoperationneedstobeperformed.Hereisaquickdescriptionofthebasiccuttingtoolsmostoftenusedinmillingoperations.DRILLAdrillisusedtocreatearound,cylindricalholeinaworkpiece.Drilledholescanbethroughholesorblindholes.Ablindholeisnotcutentirelythroughaworkpiece.Quiteoften,anengineeringblueprintwillspecifyadrilledholetobedrilledtofulldiameterdepth.Thismeansthattheholediametermustbeaspecifieddepthwithoutregardtotheangledtipofthedrill.Whenyoumeasureyourtoollengthoffset,youaremeasuringthelengthofthedrillanditstip.SohowdeepdoyoudrilltheholesothatthefulldiameterdepthiscorrectWell,youneedtoknowhowlongthedrillpointis.TIPThelengthofthedrillpointisdeterminedbythetoolpointangleandthedrilldiameter.Youcancalculatethelengthofthedrillpointbymultiplyingthedrilldiameterbyaconstantthevalueoftheconstantdependsonthedrillpointanglemoststandardhighspeedsteeldrillshaveatoolpointangleof118degrees.Foradrillpointangleof118degrees135degrees141degreesMultiplythedrilldiameterby0.30.2070.177Usingtheseconstantsallowsyoutocalculatethedrillpointlengthwithinafewthousandthsofaninch.CENTERDRILLAcenterdrillisasmalldrillwithapilotpoint.Itisusedtocreateasmallholewithtaperedwalls.Whenaholeslocationmustbeheldtoaclosetolerance,useacenterdrillfirstandthenuseatwistdrilltofinishthehole.Thetaperedwallsofthecenterdrilledholewillkeepthetwistdrillstraightwhenitbeginstodrillintotheworkpiece.TIPManymachinistsusethisruleofthumbIfthetoleranceofthediameterofacenterdrilledholeisnotcritical,drillasdeepasyouwantthisdiametertobe.Withastandard,60degreecenterdrillbelow0.375inchdiameter,theholediameterproducedwillbeclosetothedepthyoudrilled.Withlargercenterdrills–0.375inchandabove–thedepthtodiameterratiobecomeslarger,soyoucouldbeoffbyasmuchas0.080to0.100inch.REAMERAreamerisdesignedtoremoveasmallamountofmaterialfromadrilledhole.Thereamercanholdveryclosetoleranceonthediameterofahole,andgiveasuperiorsurfacefinish.Theholemustbedrilledfirst,leaving0.005to0.015inchofstockonthewallsoftheholeforthereamertoremove.TIPTheidealsituationforholesizeaccuracyandlocationwhenreamingistoprocesstheholewiththefollowingstepstheholeisfirstdrilled,thenbored,thenreamed.TIPStockallowanceforareamedholewilldependonthesizeofthehole.Ageneralruleisforholeslessthan1/2forholesgreaterthan1/2stockoflessthan0.0150ondiameterstockof0.030ondiameterThetypeofworkpiecematerialandthemethodusedtocreatetheholewillaffectthestockallowance.TIPAreamerproducesthebest,mostuniformsurfacefinishwhenitisfedintoandoutoftheholeusingtheG85borein,boreoutcannedcycle.ManypeopletrytosavetimebyusingtheG81drillcannedcycle,whichwillfeedintoaholeandrapidout.ItisquickerthanG85,butwillusuallyleaveahelicalswirlmarkonthecylindricalsurfaceofthehole.Althoughthisswirlmarkisonlyacosmeticflawanddoesntaffectthesizeofthehole,theappearanceoftheholemayberejectedbysomecustomers.TAPAtapisusedtocreatescrewthreadsinsideofadrilledhole.NOTEGreatcaremustbetakenwhenusingamillingmachinetoperformatappingoperation.TIPIfyouareusingamachinewithrigidtapping,feedrateininchesperminutethreadpitchxrevolutionsperminute.Also,youshouldnevertapmorethan1.5xthetapsmajordiameter.Threadedconnectionswillnotincreaseinstrengthifthecontactlengthismorethan1.5timesthediameterofthefastener.Ifyouneedthreadsthataredeeper,machinetapthemfirstandhandtapthemtofinisheddepth.Ifyoutapdeeperthan1.5xtheholediameter,yourchancesofbreakingthetapincreasedramatically.Chipcontrolbecomesaproblem.Whentappingblindholes,alwaysdrillasdeepaspossibletoavoidpackingchipsbelowthetap.Usingaspiralflutetapwillbringthechipsup,outofthehole.Tofurtherreducetappingheadaches,makesureallholestobetappedarefreeofchips,anduseatappingfluidspecificallydesignedforthetypeofmaterialyouarecutting.TIPTapdrillsizeisthesizeoftheholerequiredforaspecifictap.For75effectivethreadstheformulathatwilldeterminethecorrectdrillsizeisD–1/N,whereDmajordiameterofthetapandNnumberofthreadsperinchAtappedholewith75ofthreaddepthhasonly5lessstrengththan100threadandtakesonly1/3ofthecuttingforceofa100thread.ENDMILLAnendmillisshapedsimilartoadrill,butwithaflatbottom.Itisusedprimarilytocutwiththesideofthetooltocontourtheshapeofaworkpiece.TIPProgramminganendmilltocutcontourorpockettoolpathsusingcuttercompensationG41andG42allowsyoumuchmoreflexibilityinadjustingthesizeofmachinedfeatures.Usingcuttercompensationallowsyoutoadjusttheamountofstockremoval.Asanendmillwears,minoroffsetadjustmentsallowyoutomakeeverypartthesamesize.Youmayalsouseadifferentsizeendandhavethemachinecutthesamepartfeaturesaswiththeendmilloriginallyprogrammedforthattoolpath.BULLENDMILLAbullendmillisthesameasaregularendmillexceptthatthereisaradiusonthecornerwheretheflutesmeetthebottomoftheendmill.Thisradiuscanbeanysizeuptoonehalfofthetoolsdiameter.TIPBullendmillsareeffectiveforproducingacornerradiusbetweenawallandaflooronagivenpartfeature.Theyalsoaddtothestrengthofanendmill.Whenmachininghard,toughtocutmaterials,thesharpcornersonastandardendmilltendtochipandwearfasterthananendmillwithacornerradius.Theradiusonabullendmillprovidesamoregradualshearingentryintotheworkpiece.BALLENDMILLAballendmillisabullendmillwherethecornerradiusisexactly1/2thetoolsdiameter.Thisgivesthetoolasphericalshapeatthetip.Itcanbeusedtocutwithsideofthetoollikeanendmill.TIPTheprimarypurposeofaballendmillistomachineloftedsurfaces.Thesphericalshapeofthetoolisabletomovealonganyundulatingsurfaceandcutanywherealongthecuttersballend.Asaballcanrolloverasurface,aballendmillcanbeusedtocutanysuchsurface.INSERTENDMILLAninsertendmillisthesameasastandardendmillbutwithreplaceablecarbideinserts.TIPInsertendmillsaredesignedtoremovemetalathigherratesthansolidcarbide.Theycomeinalargerangeofdiametersandareabletocutatadeeperdepthofcut.Thisisfantasticbut,whenusingthesecutters,itisagoodideatocalculatethehorsepowerrequiredtomakeacut.PieceofcakeonyourHaascontrolThereisabuttononthefrontlabeledHELP/CALC.PressthisbuttononcetogettheHelpmenu,pressitagaintogettheCalculatorfunctions.UsethePAGEUP/PAGEDOWNkeystoscrollbetweenthreepagesTrigonometryHelp,CircularInterpolationHelp,andMillingHelp.Eachoneofthesepageshasasimplecalculatorintheupperlefthandcorner.OntheMillingHelppage,youcansolvethreeequations1.SFMcutterdiameterin.RPM3.14159/122.Chiploadin.feedin.permin./RPM/offlutes3.Feedin.permin.RPM/threadpitchWithallthreeequations,youmayenterallbutoneofthevaluesandthecontrolwillcomputeanddisplaytheremainingvalue.Tocalculatethehorsepowerrequiredforacut,youmustentervaluesforRPM,feedrate,numberofflutes,depthofcut,widthofcut,andchooseamaterialfromthemenu.Ifyouchangeanyoftheabovevalues,thecalculatorwillautomaticallyupdatetherequiredhorsepowerforthecutyouintend.Thenextthingtoconsiderwhenchoosingcuttingtoolsforajobiswhatmaterialyouaregoingtocut.Themostcommonmaterialscutinthemetalworkingindustrycanbedividedintotwocategoriesnonferrousandferrous.Nonferrousmaterialsincludealuminumandaluminumalloys,copperandcopperalloys,magnesiumalloys,nickelandnickelalloys,titaniumandtitaniumalloys.Commonferrousmaterialsincludecarbonsteel,alloysteel,stainlesssteel,toolsteel,andferrouscastmetalslikeiron.Nonferrousmetalsaresofterandeasiertocut,withtheexceptionofnickelandtitanium.Ferrousmetals,ontheotherhand,aregenerallyharderincompositionandtoughertocut.Cuttingtoolmaterialisoneofthebiggestdecisionsyoullhavetomakewhenchoosingacuttingtool.Mostallofthecuttersdescribedaboveareavailableinthreebasicmaterialshighspeedsteel,solidcarbide,andcarbideinsertstyle.Almostallofthebasiccuttingtoolmaterialscanbeusedtocutalmostallmaterials.Itreallyboilsdowntoperformance.Highspeedsteelcuttingtoolshaveveryhightoughnessbutlackwearresistance.Carbide,ontheotherhand,hasaveryhighwearresistancebutchipsandbreakseasily.Carbidewillalwaysbeabletocutmaterialsathigherspeedsandfeeds,butismoreexpensive.Carbideinsertcuttingtoolsareveryusefulinhighproductionsituationsbecausetheinsertsaredesignedwithmultiplecuttingedgesoneachinsert.Whentheybecomewornout,youindextheinsertstothenextcuttingedge,andwhenallcuttingedgesareused,youonlyreplacetheinsertsandnotthewholetool.TIPIfyouareusingahighspeedsteeldrill,alwaysuseacenterdrilltogettheholestarted.Thendrillthehole.Thiswillensurethatthedrilledholeisinthecorrectlocation.Ifyouareusingacarbidedrill,itisnotnecessarytocenterdrillfirstbecausecarbidedrillsaregroundwithaselfcenteringtip.Usingacarbidedrilltodrillaholethatisalreadycenterdrilledwilldamagethedrill.Theoutercuttingedgeswillcontactthetaperedwallsbeforethetipofthedrillbeginstocut.Thiswillshocktheoutercuttingedgesandcausethedrilltochip.Carbidedrillsmustbegintocutatthetipbeforetheoutercuttingedges.Eachoneofthesecuttingtoolmaterialsisavailablewithavarietyofdifferentcoatingstoenhancetheirperformance.ThethreecoatingsmostwidelyusetodayaretitaniumnitrideTiN,titaniumcarbonitrideTiCN,andtitaniumaluminumnitrideTiAlN.TiNcoatingiseasilyrecognizedbyitsgoldcolor.TheadvantagesofTiNcoatingareincreasedsurfacehardness,increasedtoollife,betterwearresistanceandhigherlubricity,whichdecreasesfrictionandreducesedgebuildup.TiNcoatingismostlyrecommendedformachininglowalloysteelandstainlesssteel.TiCNcoatingisgraycoloredcomparedtoTiN,andevenharder.Itsadvantagesareincreasedcuttingspeedandfeeds40to60highercomparedtoTiN,highermetalremovalrates,andsuperiorwearresistance.TiCNcoatingsarerecommendedformachiningallmaterialtypes.TiAlNcoatingappearsgrayorblackandisprimarilyusedtocoatcarbide.Itcanworkatveryhightemperatures,upto800degreesCelsius,whichmakesitidealforhighspeedmachiningwithoutcoolant.Pressurizedairisrecommendedtoremovechipsfromthecuttingzone.Itworkswellonhardenedsteels,titaniumandnickelalloys,aswellasabrasivematerialslikecastironandhighsiliconaluminum.Whenselectingendmilltools,thenumberofflutes,orcuttingedges,isanimportantfactor.Themoreflutesanendmillhas,thesmaller,orshallower,theflutesare.Thesolidcentersectionofanendmillisapproximately52oftheendmillsdiameteronatwofluteendmill.Thecentersectionofathreefluteendmillis56ofitsdiameter,andanendmillwithfourormorefluteshasacentersectionthatis61ofitsdiameter.Thismeansthatthemoreflutesanendmillhas,themorerigiditwillbeinthecut.Twofluteendmillsarerecommendedforsoft,gummymaterialssuchasaluminumandcopper.Fourfluteendmillsarerecommendedforharder,toughersteelmaterials.中文译文切削刀具

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