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英文原文CUTTINGTOOLSWhenselectingcuttingtoolsforajob,thefirstthingtoconsideriswhattypeofoperationneedstobeperformed.Hereisaquickdescriptionofthebasiccuttingtoolsmostoftenusedinmillingoperations.DRILLAdrillisusedtocreatearound,cylindricalholeinaworkpiece.Drilledholescanbe"throughholes"or"blindholes".A"blindhole"isnotcutentirelythroughaworkpiece.Quiteoften,anengineeringblueprintwillspecifyadrilledholetobedrilledto"fulldiameterdepth."Thismeansthattheholediametermustbeaspecifieddepthwithoutregardtotheangledtipofthedrill.Whenyoumeasureyourtoollengthoffset,youaremeasuringthelengthofthedrillanditstip.Sohowdeepdoyoudrilltheholesothatthefulldiameterdepthiscorrect?Well,youneedtoknowhowlongthedrillpointis.TIP:Thelengthofthedrillpointisdeterminedbythetoolpointangleandthedrilldiameter.Youcancalculatethelengthofthedrillpointbymultiplyingthedrilldiameterbyaconstant；thevalueoftheconstantdependsonthedrillpointangle(moststandardhigh-speedsteeldrillshaveatoolpointangleof118degrees).Foradrillpointangleof:118degrees135degrees141degreesMultiplythedrilldiameterby:0.30.2070.177Usingtheseconstantsallowsyoutocalculatethedrillpointlengthwithinafewthousandthsofaninch.CENTERDRILLAcenterdrillisasmalldrillwithapilotpoint.Itisusedtocreateasmallholewithtaperedwalls.Whenaholeslocationmustbeheldtoaclosetolerance,useacenterdrillfirstandthenuseatwistdrilltofinishthehole.Thetaperedwallsofthecenter-drilledholewillkeepthetwistdrillstraightwhenitbeginstodrillintotheworkpiece.TIP:Manymachinistsusethisruleofthumb:Ifthetoleranceofthediameterofacenter-drilledholeisnotcritical,drillasdeepasyouwantthisdiametertobe.Withastandard,60-degreecenterdrillbelow0.375-inchdiameter,theholediameterproducedwillbeclosetothedepthyoudrilled.Withlargercenterdrills0.375inchandabovethedepth-to-diameterratiobecomeslarger,soyoucouldbeoffbyasmuchas0.080to0.100inch.REAMERAreamerisdesignedtoremoveasmallamountofmaterialfromadrilledhole.Thereamercanholdveryclosetoleranceonthediameterofahole,andgiveasuperiorsurfacefinish.Theholemustbedrilledfirst,leaving0.005to0.015inchofstockonthewallsoftheholeforthereamertoremove.TIP:Theidealsituationforholesizeaccuracyandlocationwhenreamingistoprocesstheholewiththefollowingsteps:theholeisfirstdrilled,thenbored,thenreamed.TIP:Stockallowanceforareamedholewilldependonthesizeofthehole.Ageneralruleis:forholeslessthan1/2"forholesgreaterthan1/2"stockoflessthan0.0150"ondiameterstockof0.030"ondiameterThetypeofworkpiecematerialandthemethodusedtocreatetheholewillaffectthestockallowance.TIP:Areamerproducesthebest,mostuniformsurfacefinishwhenitisfedintoandoutoftheholeusingtheG85(borein,boreout)cannedcycle.ManypeopletrytosavetimebyusingtheG81(drill)cannedcycle,whichwillfeedintoaholeandrapidout.ItisquickerthanG85,butwillusuallyleaveahelicalswirlmarkonthecylindricalsurfaceofthehole.Althoughthisswirlmarkisonlyacosmeticflawanddoesntaffectthesizeofthehole,theappearanceoftheholemayberejectedbysomecustomers.TAPAtapisusedtocreatescrewthreadsinsideofadrilledhole.NOTE:Greatcaremustbetakenwhenusingamillingmachinetoperformatappingoperation.TIP:Ifyouareusingamachinewithrigidtapping,feedrate(ininchesperminute)=threadpitchxrevolutionsperminute.Also,youshouldnevertapmorethan1.5xthetapsmajordiameter.Threadedconnectionswillnotincreaseinstrengthifthecontactlengthismorethan1.5timesthediameterofthefastener.Ifyouneedthreadsthataredeeper,machinetapthemfirstandhand-tapthemtofinisheddepth.Ifyoutapdeeperthan1.5xtheholediameter,yourchancesofbreakingthetapincreasedramatically.Chipcontrolbecomesaproblem.Whentappingblindholes,alwaysdrillasdeepaspossibletoavoidpackingchipsbelowthetap.Usingaspiralflutetapwillbringthechipsup,outofthehole.Tofurtherreducetappingheadaches,makesureallholestobetappedarefreeofchips,anduseatappingfluidspecificallydesignedforthetypeofmaterialyouarecutting.TIP:Tapdrillsizeisthesizeoftheholerequiredforaspecifictap.For75%effectivethreadstheformulathatwilldeterminethecorrectdrillsizeis:D1/N,whereD=majordiameterofthetapandN=numberofthreadsperinchAtappedholewith75%ofthreaddepthhasonly5%lessstrengththan100%threadandtakesonly1/3ofthecuttingforceofa100%thread.ENDMILLAnendmillisshapedsimilartoadrill,butwithaflatbottom.Itisusedprimarilytocutwiththesideofthetooltocontourtheshapeofaworkpiece.TIP:Programminganendmilltocutcontourorpockettoolpathsusingcuttercompensation(G41andG42)allowsyoumuchmoreflexibilityinadjustingthesizeofmachinedfeatures.Usingcuttercompensationallowsyoutoadjusttheamountofstockremoval.Asanendmillwears,minoroffsetadjustmentsallowyoutomakeeverypartthesamesize.Youmayalsouseadifferentsizeendandhavethemachinecutthesamepartfeaturesaswiththeendmilloriginallyprogrammedforthattoolpath.BULLENDMILLAbullendmillisthesameasaregularendmillexceptthatthereisaradiusonthecornerwheretheflutesmeetthebottomoftheendmill.Thisradiuscanbeanysizeuptoone-halfofthetoolsdiameter.TIP:Bullendmillsareeffectiveforproducingacornerradiusbetweenawallandaflooronagivenpartfeature.Theyalsoaddtothestrengthofanendmill.Whenmachininghard,toughtocutmaterials,thesharpcornersonastandardendmilltendtochipandwearfasterthananendmillwithacornerradius.Theradiusonabullendmillprovidesamoregradualshearingentryintotheworkpiece.BALLENDMILLAballendmillisabullendmillwherethecornerradiusisexactly1/2thetoolsdiameter.Thisgivesthetoolasphericalshapeatthetip.Itcanbeusedtocutwithsideofthetoollikeanendmill.TIP:Theprimarypurposeofaballendmillistomachineloftedsurfaces.Thesphericalshapeofthetoolisabletomovealonganyundulatingsurfaceandcutanywherealongthecutters"ballend."Asaballcanrolloverasurface,aballendmillcanbeusedtocutanysuchsurface.INSERTENDMILLAninsertendmillisthesameasastandardendmillbutwithreplaceablecarbideinserts.TIP:Insertendmillsaredesignedtoremovemetalathigherratesthansolidcarbide.Theycomeinalargerangeofdiametersandareabletocutatadeeperdepthofcut.Thisisfantasticbut,whenusingthesecutters,itisagoodideatocalculatethehorsepowerrequiredtomakeacut.PieceofcakeonyourHaascontrol:Thereisabuttononthefrontlabeled"HELP/CALC."PressthisbuttononcetogettheHelpmenu,pressitagaintogettheCalculatorfunctions.UsethePAGEUP/PAGEDOWNkeystoscrollbetweenthreepages:TrigonometryHelp,CircularInterpolationHelp,andMillingHelp.Eachoneofthesepageshasasimplecalculatorintheupperlefthandcorner.OntheMillingHelppage,youcansolvethreeequations:1.SFM=(cutterdiameterin.)*RPM*3.14159/122.(Chiploadin.)=(feedin.permin.)/RPM/#offlutes3.(Feedin.permin.)=RPM/(threadpitch)Withallthreeequations,youmayenterallbutoneofthevaluesandthecontrolwillcomputeanddisplaytheremainingvalue.Tocalculatethehorsepowerrequiredforacut,youmustentervaluesforRPM,feedrate,numberofflutes,depthofcut,widthofcut,andchooseamaterialfromthemenu.Ifyouchangeanyoftheabovevalues,thecalculatorwillautomaticallyupdatetherequiredhorsepowerforthecutyouintend.Thenextthingtoconsiderwhenchoosingcuttingtoolsforajobiswhatmaterialyouaregoingtocut.Themostcommonmaterialscutinthemetalworkingindustrycanbedividedintotwocategories:non-ferrousandferrous.Non-ferrousmaterialsincludealuminumandaluminumalloys,copperandcopperalloys,magnesiumalloys,nickelandnickelalloys,titaniumandtitaniumalloys.Commonferrousmaterialsincludecarbonsteel,alloysteel,stainlesssteel,toolsteel,andferrouscastmetalslikeiron.Non-ferrousmetalsaresofterandeasiertocut,withtheexceptionofnickelandtitanium.Ferrousmetals,ontheotherhand,aregenerallyharderincompositionandtoughertocut.Cuttingtoolmaterialisoneofthebiggestdecisionsyoullhavetomakewhenchoosingacuttingtool.Mostallofthecuttersdescribedaboveareavailableinthreebasicmaterials:high-speedsteel,solidcarbide,andcarbideinsertstyle.Almostallofthebasiccuttingtoolmaterialscanbeusedtocutalmostallmaterials.Itreallyboilsdowntoperformance.High-speedsteelcuttingtoolshaveveryhightoughnessbutlackwearresistance.Carbide,ontheotherhand,hasaveryhighwearresistancebutchipsandbreakseasily.Carbidewillalwaysbeabletocutmaterialsathigherspeedsandfeeds,butismoreexpensive.Carbideinsertcuttingtoolsareveryusefulinhigh-productionsituationsbecausetheinsertsaredesignedwithmultiplecuttingedgesoneachinsert.Whentheybecomewornout,youindextheinsertstothenextcuttingedge,andwhenallcuttingedgesareused,youonlyreplacetheinsertsandnotthewholetool.TIP:Ifyouareusingahigh-speedsteeldrill,alwaysuseacenterdrilltogettheholestarted.Thendrillthehole.Thiswillensurethatthedrilledholeisinthecorrectlocation.Ifyouareusingacarbidedrill,itisnotnecessarytocenterdrillfirstbecausecarbidedrillsaregroundwithaself-centeringtip.Usingacarbidedrilltodrillaholethatisalreadycenterdrilledwilldamagethedrill.Theoutercuttingedgeswillcontactthetaperedwallsbeforethetipofthedrillbeginstocut.Thiswillshocktheoutercuttingedgesandcausethedrilltochip.Carbidedrillsmustbegintocutatthetipbeforetheoutercuttingedges.Eachoneofthesecuttingtoolmaterialsisavailablewithavarietyofdifferentcoatingstoenhancetheirperformance.Thethreecoatingsmostwidelyusetodayaretitaniumnitride(TiN),titaniumcarbonitride(TiCN),andtitaniumaluminumnitride(TiAlN).TiNcoatingiseasilyrecognizedbyitsgoldcolor.TheadvantagesofTiNcoatingareincreasedsurfacehardness,increasedtoollife,betterwearresistanceandhigherlubricity,whichdecreasesfrictionandreducesedgebuild-up.TiNcoatingismostlyrecommendedformachininglowalloysteelandstainlesssteel.TiCNcoatingisgraycoloredcomparedtoTiN,andevenharder.Itsadvantagesareincreasedcuttingspeedandfeeds(40%to60%highercomparedtoTiN),highermetalremovalrates,andsuperiorwearresistance.TiCNcoatingsarerecommendedformachiningallmaterialtypes.TiAlNcoatingappearsgrayorblackandisprimarilyusedtocoatcarbide.Itcanworkatveryhightemperatures,upto800degreesCelsius,whichmakesitidealforhigh-speedmachiningwithoutcoolant.Pressurizedairisrecommendedtoremovechipsfromthecuttingzone.Itworkswellonhardenedsteels,titaniumandnickelalloys,aswellasabrasivematerialslikecastironandhighsiliconaluminum.Whenselectingendmilltools,thenumberofflutes,orcuttingedges,isanimportantfactor.Themoreflutesanendmillhas,thesmaller,orshallower,theflutesare.Thesolidcentersectionofanendmillisapproximately52%oftheendmillsdiameteronatwo-fluteendmill.Thecentersectionofathree-fluteendmillis56%ofitsdiameter,andanendmillwithfourormorefluteshasacentersectionthatis61%ofitsdiameter.Thismeansthatthemoreflutesanendmillhas,themorerigiditwillbeinthecut.Two-fluteendmillsarerecommendedforsoft,gummymaterialssuchasaluminumandcopper.Four-fluteendmillsarerecommendedforharder,toughersteelmaterials.中文译文切削刀具