机械工具的根本原则毕业课程设计外文文献翻译、中英文翻译、外文翻译

第0页共35页TCNO9524JOELBHUDSON,DENNISJREIMERWASHINGTON,DC,29OCTOBER1996ATTNATCLAO,801LEEAVENUE,FORTLEE,VIRGINIA238011713FUNDAMENTALSOFMACHINETOOLSCHAPTER4DRILLINGMACHINESGENERALINFORMATIONPURPOSETHISCHAPTERCONTAINSBASICINFORMATIONPERTAININGTODRILLINGMACHINESADRILLINGMACHINECOMESINMANYSHAPESANDSIZES,FROMSMALLHANDHELDPOWERDRILLSTOBENCHMOUNTEDANDFINALLYFLOORMOUNTEDMODELSTHEYCANPERFORMOPERATIONSOTHERTHANDRILLING,SUCHASCOUNTERSINKING,COUNTERBORING,REAMING,ANDTAPPINGLARGEORSMALLHOLESBECAUSETHEDRILLINGMACHINESCANPERFORMALLOFTHESEOPERATIONS,THISCHAPTERWILLALSOCOVERTHETYPESOFDRILLBITS,TOOK,ANDSHOPFORMULASFORSETTINGUPEACHOPERATIONSAFETYPLAYSACRITICALPARTINANYOPERATIONINVOLVINGPOWEREQUIPMENTTHISCHAPTERWILLCOVERPROCEDURESFORSERVICING,MAINTAINING,ANDSETTINGUPTHEWORK,PROPERMETHODSOFSELECTINGTOOLS,ANDWORKHOLDINGDEVICESTOGETTHEJOBDONESAFELYWITHOUTCAUSINGDAMAGETOTHEEQUIPMENT,YOURSELF,ORSOMEONENEARBYUSESADRILLINGMACHINE,CALLEDADRILLPRESS,ISUSEDTOCUTHOLESINTOORTHROUGHMETAL,WOOD,OROTHERMATERIALSFIGURE41DRILLINGMACHINESUSEADRILLINGTOOLTHATHASCUTTINGEDGESATITSPOINTTHISCUTTINGTOOLISHELDINTHEDRILLPRESSBYACHUCKORMORSETAPERANDISROTATEDANDFEDINTOTHEWORKATVARIABLESPEEDSDRILLINGMACHINESMAYBEUSEDTOPERFORMOTHEROPERATIONSTHEYCANPERFORMCOUNTERSINKING,BORING,COUNTERBORING,SPOTFACING,REAMING,ANDTAPPINGFIGURE42DRILLPRESSOPERATORSMUSTKNOWHOWTOSETUPTHEWORK,SETSPEEDANDFEED,ANDPROVIDEFORCOOLANTTOGETANACCEPTABLEFINISHEDPRODUCTTHESIZEORCAPACITYOFTHE第1页共35页DRILLINGMACHINEISUSUALLYDETERMINEDBYTHELARGESTPIECEOFSTOCKTHATCANBECENTERDRILLEDFIGURE43FORINSTANCE,A15INCHDRILLINGMACHINECANCENTERDRILLA30INCHDIAMETERPIECEOFSTOCKOTHERWAYSTODETERMINETHESIZEOFTHEDRILLPRESSAREBYTHELARGESTHOLETHATCANBEDRILLED,THEDISTANCEBETWEENTHESPINDLEANDCOLUMN,ANDTHEVERTICALDISTANCEBETWEENTHEWORKTABLEANDSPINDLE第2页共35页CHARACTERISTICSALLDRILLINGMACHINESHAVETHEFOLLOWINGCONSTRUCTIONCHARACTERISTICSFIGURE44ASPINDLESLEEVEORQUILLCOLUMN,HEAD,WORKTABLE,ANDBASETHESPINDLEHOLDSTHEDRILLORCUTTINGTOOLSANDREVOLVESINAFIXEDPOSITIONINASLEEVEINMOSTDRILLINGMACHINES,THESPINDLEISVERTICALANDTHEWORKISSUPPORTEDONAHORIZONTALTABLETHESLEEVEORQUILLASSEMBLYDOESNOTREVOLVEBUTMAYSLIDEINITSBEARINGINADIRECTIONPARALLELTOITSAXISWHENTHESLEEVECARRYINGTHESPINDLEWITHACUTTINGTOOLISLOWERED,THECUTTINGTOOLISFEDINTOTHEWORKANDWHENITISMOVEDUPWARD,THECUTTINGTOOLISWITHDRAWNFROMTHEWORKFEEDPRESSUREAPPLIEDTOTHESLEEVEBYHANDORPOWERCAUSESTHEREVOLVINGDRILLTOCUTITSWAYINTOTHEWORKAFEWTHOUSANDTHSOFANINCHPERREVOLUTION第3页共35页THECOLUMNOFMOSTDRILLPRESSESISCIRCULARANDBUILTRUGGEDANDSOLIDTHECOLUMNSUPPORTSTHEHEADANDTHESLEEVEORQUILLASSEMBLYTHEHEADOFTHEDRILLPRESSISCOMPOSEDOFTHESLEEVE,SPINDLE,ELECTRICMOTOR,ANDFEEDMECHANISMTHEHEADISBOLTEDTOTHECOLUMNTHEWORKTABLEISSUPPORTEDONANARMMOUNTEDTOTHECOLUMNTHEWORKTABLECANBEADJUSTEDVERTICALLYTOACCOMMODATEDIFFERENTHEIGHTSOFWORKORITMAYBESWUNGCOMPLETELYOUTOFTHEWAYITMAYBETILTEDUPTO90INEITHERDIRECTION,TOALLOWFORLONGPIECESTOBEENDORANGLEDDRILLEDTHEBASEOFTHEDRILLINGMACHINESUPPORTSTHEENTIREMACHINEANDWHENBOLTEDTOTHEFLOOR,PROVIDESFORVIBRATIONFREEOPERATIONANDBESTMACHININGACCURACYTHETOPOFTHEBASEISSIMILARTOAWORKTABLEANDMAYBEEQUIPPEDWITHTSLOTSFORMOUNTINGWORKTOOLARGEFORTHETABLECAREOFDRILLINGMACHINESLUBRICATIONLUBRICATIONISIMPORTANTBECAUSEOFTHEHEATANDFRICTIONGENERATEDBYTHEMOVINGPARTSFOLLOWTHEMANUFACTURERSMANUALFORPROPERLUBRICATIONMETHODSCLEANEACHMACHINEAFTERUSECLEANTSLOTSGROOVESANDDIRTFROMBELTSANDPULLEYSREMOVECHIPSTOAVOIDDAMAGETOMOVINGPARTSWIPEALLSPINDLESANDSLEEVESFREEOFGRITTOAVOIDDAMAGINGTHEPRECISIONFITPUTALIGHTCOATOFOILONALLUNPAINTEDSURFACESTOPREVENTRUSTOPERATEALLMACHINESWITHCARETOAVOIDOVERWORKINGTHEELECTRICMOTORSPECIALCAREOPERATIONSUNDERADVERSECONDITIONSREQUIRESPECIALCAREIFMACHINESAREOPERATEDUNDEREXTREMELYDUSTYCONDITIONSOPERATEATTHESLOWESTSPEEDSTOAVOIDRAPIDABRASIVEWEARONTHEMOVINGPARTSANDLUBRICATETHEMACHINESMOREOFTENUNDEREXTREMECOLDCONDITIONS,STARTTHEMACHINESATASLOWSPEEDANDALLOWTHEPARTSANDLUBRICANTSTOWARMUPBEFOREINCREASINGTHESPEEDSMETALBECOMESVERYBRITTLEINEXTREMECOLDSODONOTSTRIKETHEMACHINESWITHHARDTOOLSEXTREMEHEATMAYCAUSETHEMOTORTOOVERHEATSOUSEINTERMITTENTORONANDOFF,OPERATIONSTOKEEPTHEMOTORRUNNINGCOOLTYPESOFDRILLINGMACHINESTHEREARETWOTYPESOFDRILLINGMACHINESUSEDBYMAINTENANCEPERSONNELFORREPAIRINGANDFABRICATINGNEEDEDPARTSHANDFEEDORPOWERFEEDOTHERTYPESOF第4页共35页DRILLINGMACHINES,SUCHASTHERADIALDRILLPRESSNUMERICALLYCONTROLLEDDRILLINGMACHINEMULTIPLESPINDLEDRILLINGMACHINE,GANGDRILLINGMACHINE,ANDTURRETDRILLPRESS,AREALLVARIATIONSOFTHEBASICHANDANDPOWERFEEDDRILLINGMACHINESTHEYAREDESIGNEDFORHIGHSPEEDPRODUCTIONANDINDUSTRIALSHOPSDRILLINGDEPTHISCONTROLLEDBYADEPTHSTOPMECHANISMLOCATEDONTHESIDEOFTHESPINDLETHEOPERATOROFTHEMACHINEMUSTUSEASENSEOFFEELWHILEFEEDINGTHECUTTINGTOOLINTOTHEWORKTHEOPERATORMUSTPAYATTENTIONANDBEALERTTOWHENTHEDRILLBREAKSTHROUGHTHEWORK,BECAUSEOFTHETENDENCYOFTHEDRILLTOGRABORSNAGTHEWORKPIECE,OFTHESEMACHINES,OPERATIONSTHATREQUIREDRILLINGSPEEDSLESSTHAN450REVOLUTIONSPERMINUTECANNOTBEPERFORMEDREAMING,COUNTERBORING,ANDCOUNTERSINKINGMAYREQUIRESLOWERSPEEDSTHANDRILLINGANDMAYNOTBEABLETOBEPERFORMEDFORALLMATERIALSONTHESEMACHINESHANDFEEDTHEHANDFEEDDRILLINGMACHINESFIGURE45ARETHESIMPLESTANDMOSTCOMMONTYPEOFDRILLINGMACHINESINUSETODAYTHESEARELIGHTDUTYMACHINESTHATAREHANDFEDBYTHEOPERATOR,USINGAFEEDHANDLESOTHATTHEOPERATORISABLETO“FEEL”THEACTIONOFTHECUTTINGTOOLASITCUTSTHROUGHTHEWORKPIECETHESEDRILLINGMACHINESCANBEBENCHORFLOORMOUNTEDTHEYAREDRIVENBYANELECTRICMOTORTHATTURNSADRIVEBELTONAMOTORPULLEYTHATCONNECTSTOTHESPINDLEPULLEYHANDFEEDMACHINESAREESSENTIALLYHIGHSPEEDMACHINESANDAREUSEDONSMALLWORKPLACESTHATREQUIREHOLES1/2INCHORSMALLERNORMALLY,THEHEADCANBEMOVEDUPANDDOWNONTHECOLUMNBYLOOSENINGTHELOCKINGBOLTSWHICHALLOWSTHEDRILLINGMACHINETODRILLDIFFERENTHEIGHTSOFWORKPOWERFEEDTHEPOWERFEEDDRILLINGMACHINESFIGURE46AREUSUALLYLARGERANDHEAVIERTHANTHEHANDFEEDTHEYAREEQUIPPEDWITHTHEABILITYTOFEEDTHECUTTINGTOOLINTOTHEWORKAUTOMATICALLY,ATAPRESETDEPTHOFCUTPERREVOLUTIONOFTHESPINDLE,USUALLYINTHOUSANDTHSOFANINCHPERREVOLUTIONTHESEMACHINESAREUSEDINMAINTENANCESHOPSFORMEDIUMDUTYWORK,ORWORKTHATUSESLARGEDRILLSTHATREQUIREPOWERFEEDSTHEPOWERFEEDCAPABILITYISNEEDEDFORDRILLSORCUTTINGTOOKTHATAREOVER1/2INCHINDIAMETER,BECAUSETHEYREQUIREMOREFORCETOCUTTHANTHATWHICHCANBEPROVIDEDBYUSINGHANDPRESSURETHESPEEDSAVAILABLEONPOWERFEEDMACHINESCANVARYFROMABOUT50RPMTOABOUT1,800RPMTHESLOWERSPEEDSALLOWFORSPECIALOPERATIONS,SUCHASCOUNTERBORING,COUNTERSINKING,ANDREAMING第5页共35页THESIZESOFTHESEMACHINESGENERALLYRANGEFROM17INCHTOA22INCHCENTERDRILLINGCAPACITY,ANDAREUSUALLYFLOORMOUNTEDTHEYCANHANDLEDRILLSUPTO2INCHESINDIAMETER,WHICHMOUNTINTOTAPEREDMORSESOCKETSLARGERWORKPLACESAREUSUALLYCLAMPEDDIRECTLYTOTHETABLEORBASEUSINGTBOLTSANDCLAMPS,WHILESMALLWORKPLACESAREHELDINAVISEADEPTHSTOPMECHANISMISLOCATEDONTHEHEAD,NEARTHESPINDLE,TOAIDINDRILLINGTOAPRECISEDEPTHSAFETYPRECAUTIONSDRILLINGMACHINESAFETYDRILLINGMACHINESAREONEOFTHEMOSTDANGEROUSHANDOPERATEDPIECESOFEQUIPMENTINTHESHOPAREAFOLLOWINGSAFETYPROCEDURESDURINGDRILLINGOPERATIONSWILLHELPELIMINATEACCIDENTS,LOSSOFTIME,ANDMATERIALSLISTEDBELOWKEEPALLLOOSECLOTHINGAWAYFROMTURNINGTOOLSARESAFETYPROCEDURESCOMMONTOMOSTTYPESOFDRILLINGACHINESFOUNDINTHEMACHINESHOPMAKESURETHATTHECUTTINGTOOLSARERUNNINGSTRAIGHTBEFORESTARTINGTHEOPERATIONDONOTSUPPORTTHEWORKPLACESBYHANDNEVERMAKEANYADJUSTMENTSWHILETHEMACHINEISOPERATINGNEVERCLEANAWAYCHIPSWITHYOURHANDUSEABRUSHNEVERPLACETOOLSOREQUIPMENTONTHEDRILLINGTABLESKEEPALLGUARDSINPLACEWHILEOPERATINGEASEUPONTHEFEEDASTHEDRILLBREAKSTHROUGHTHEWORKTOAVOIDDAMAGEDTOOLSORWORKPLACES第6页共35页REMOVEALLCHUCKKEYSANDWRENCHESBEFOREOPERATINGALWAYSWEAREYEPROTECTIONWHILEOPERATINGANYDRILLINGMACHINESTOOLSANDEQUIPMENTTWISTDRILLSTWISTDRILLSARETHEMOSTCOMMONCUTTINGTOOLSUSEDWITHDRILLINGMACHINESTWISTDRILLSAREDESIGNEDTOMAKEROUNDHOLESQUICKLYANDACCURATELYINALLMATERIALSTHEYARECALLEDTWISTDRILLSMAINLYBECAUSEOFTHEHELICALFLUTESORGROOVESTHATWINDAROUNDTHEBODYFROMTHEPOINTTOTHENECKOFTHEDRILLANDAPPEARTOBETWISTEDFIGURE47TWISTDRILLSARESIMPLYCONSTRUCTEDBUTDESIGNEDVERYTOUGHTOWITHSTANDTHEHIGHTORQUEOFTURNING,THEDOWNWARDPRESSUREONTHEDRILL,ANDTHEHIGHHEATGENERATEDBYFRICTIONTHEREARETWOCOMMONTYPESOFTWISTDRILLS,HIGHSPEEDSTEELDRILLS,ANDCARBIDETIPPEDDRILLSTHEMOSTCOMMONTYPEUSEDFORFIELDANDMAINTENANCESHOPWORKISTHEHIGHSPEEDSTEELTWISTDRILLBECAUSEOFITSLOWCOSTCARBIDETIPPEDMETALDRILLSAREUSEDINPRODUCTIONWORKWHERETHEDRILLMUSTREMAINSHARPFOREXTENDEDPERIODS,SUCHASINANUMERICALLYCONTROLLEDDRILLINGMACHINEOTHERTYPESOFDRILLSAVAILABLEARECARBIDETIPPEDMASONRYDRILLS,SOLIDCARBIDEDRILLS,TINCOATEDDRILLS,PARABOLICDRILLSANDSPLITPOINTDRILLSTWISTDRILLSARECLASSIFIEDASSTRAIGHTSHANKORTAPEREDSHANKFIGURE47STRAIGHTSHANKTWISTDRILLSAREUSUALLYL/2INCHORSMALLERANDTITINTOGEAREDDRILLCHUCKS,WHILETAPEREDSHANKDRILLSAREUSUALLYFORTHELARGERDRILLSTHAT第7页共35页NEEDMORESTRENGTHWHICHISPROVIDEDBYTHETAPERSOCKETCHUCKSCOMMONTWISTDRILLSIZESRANGEFROM00135WIREGAGESIZENO80TO3500INCHESINDIAMETERLARGERHOLESARECUTBYSPECIALDRILLSTHATARENOTCONSIDEREDASTWISTDRILLSTHESTANDARDSIZESUSEDINTHEUNITEDSTATESARETHEWIREGAGENUMBEREDDRILLS,LETTERDRILLS,FRACTIONALDRILLS,ANDMETRICDRILLSSEETABLE41,INAPPENDIXATWISTDRILLSCANALSOBECLASSIFIEDBYTHEDIAMETERANDLENGTHOFTHESHANKANDBYTHELENGTHOFTHEFLUTEDPORTIONOFTHETWISTDRILLWIREGAGETWISTDRILLSANDLETTERTWISTDRILLSAREGENERALLYUSEDWHEREOTHERTHANSTANDARDFRACTIONALSIZESAREREQUIRED,SUCHASDRILLINGHOLESFORTAPPINGINTHISCASE,THEDRILLEDHOLEFORMSTHEMINORDIAMETEROFTHETHREADTOBECUT,ANDTHEMAJORDIAMETERWHICHISCUTBYTAPPINGCORRESPONDSTOTHECOMMONFRACTIONALSIZEOFTHESCREWWIREGAGETWISTDRILLSRANGEFROMTHESMALLESTTOTHELARGESTSIZEFROMNO8000135INCHTONO102280INCHTHELARGERTHENUMBER,THESMALLERTHEDIAMETEROFTHEDRILLLETTERSIZETWISTSDRILLSRANGEFROMA0234INCHTOZ0413INCHASTHELETTERSPROGRESS,THEDIAMETERSBECOMELARGERFRACTIONALDRILLSRANGEFROM1/64TO13/4INCHESINL/64INCHUNITSFROM1/32TO21/4INCHESIN1/32INCHUNITS,ANDFROM1/16TO31/2INCHESIN1/16INCHUNITSMETRICTWISTDRILLSARERANGEDINTHREEWAYSMINIATURESET,STRAIGHTSHANK,ANDTAPERSHANKMINIATUREMETRICDRILLSETSRANGEFROM004MMTO099MMINUNITSOF001MMSTRAIGHTSHANKMETRICDRILLSRANGEFROM005MMTO200MMINUNITSFROM002MMTO005MMDEPENDINGONTHESIZEOFTHEDRILLTAPERSHANKDRILLSRANGEINSIZEFROM8MMTO80MMINUNITSFROM001MMTO005MMDEPENDINGONTHESIZEOFTHEDRILLTHEDRILLGAGEFIGURE48ISUSEDTOCHECKTHEDIAMETERSIZEOFATWISTDRILLTHEGAGECONSISTSOFAPLATEHAVINGASERIESOFHOLESTHESEHOLESCANBENUMBERED,LETTERED,FRACTIONAL,ORMETRICSIZEDTWISTDRILLSTHECUTTINGENDOFTHEDRILLISPLACEDINTOTHEHOLETOCHECKTHESIZEAMICROMETERCANALSOBEUSEDTOCHECKTHESIZEOFATWISTDRILLBYMEASURINGOVERTHEMARGINSOFTHEDRILLFIGURE49THESMALLERSIZESOFDRILLSARENOTUSUALLYMARKEDWITHTHEDRILLSIZEORWORNDRILLSMAYHAVETHEDRILLSIZERUBBEDOFF,THUSADRILLGAGEORMICROMETERMUSTBEUSEDTOCHECKTHESIZEITISIMPORTANTTOKNOWTHEPARTSOFTHETWISTDRILLFORPROPERIDENTIFICATIONANDSHARPENINGFIGURE47THEPOINTISTHEENTIRECONICALSHAPEDENDOFTHEDRILLCONTAININGTHECUTTINGEDGES第8页共35页ANDCHISELEDGETHEBODYISTHEPARTOFTHEDRILLTHATISFLUTEDANDRELIEVEDTHESHANKISTHEPARTTHATFITSINTOTHEHOLDINGDEVICE,WHETHERITISASTRAIGHTSHANKORATAPEREDSHANKTHECHISELEDGEISTHEPOINTATWHICHTHETWOLIPSMEETTHE第9页共35页CHISELEDGEACTSASACHISELWHENTHEDRILLISTURNINGANDCUTSINTOTHEWORKPIECETHECHISELEDGEMUSTALWAYSBECENTEREDEXACTLYONTHEDRILLSAXISFORACCURATECUTTINGACTIONTHECUTTINGEDGELIPSCUTLIKEKNIVESWHENFEDANDROTATEDINTOTHEWORKPIECETHELIPSARESHARPEDGESFORMEDBYGRINDINGTHEFLUTESTOACONICALPOINTTHEHEELISTHECONICALSHAPEDPORTIONOFTHEPOINTINBACKOFTHECUTTINGEDGELIPSTHEAMOUNTOFSLOPEGIVENTOTHEHEELINBACKOFTHEDRILLLIPSISCALLEDLIPCLEARANCETHISCLEARANCEISNECESSARYTOKEEPTHEHEELFROMRUBBINGTHEBOTTOMOFTHEHOLEBEINGDRILLEDRUBBINGWOULDPREVENTTHEDRILLFROMCUTTINGTHEFLUTEISTHEHELICALGROOVEONTHEDRILLITCARRIESOUTTHECHIPSANDADMITSCOOLANTTOTHECUTTINGEDGESTHEMARGINISTHENARROWSURFACEALONGTHEFLUTESTHATDETERMINESTHESIZEOFTHEDRILLANDKEEPSTHEDRILLALIGNEDTHEPORTIONOFTHEDRILLBODYTHATISRELIEVEDBEHINDTHEMARGINISKNOWNASTHEBODYCLEARANCETHEDIAMETEROFTHISPARTISLESSTHANTHATOFTHEMARGINANDPROVIDESCLEARANCESOTHATALLOFTHEBODYDOESNOTRUBAGAINSTTHESIDEOFTHEHOLEANDCAUSEFRICTIONTHEBODYCLEARANCEALSOPERMITSPASSAGEOFLUBRICANTSAROUNDTHEDRILLTHENARROWEDENDOFTHETAPEREDSHANKDRILLISCALLEDTHETANGTHETANGFITSTHESLOTINTHEINNERMOSTENDOFTHEDRILLSPINDLE,DRILLCHUCK,OROTHERDRILLHOLDINGDEVICEANDAIDSINDRIVINGTHETOOLITALSOPREVENTSTHEDRILLFROMSLIPPINGTHEWEBOFTHEDRILLISTHEMETALSECTIONSEPARATINGTHEFLUTESITRUNSTHELENGTHOFTHEBODYBETWEENTHEFLUTESTHEWEBGRADUALLYINCREASESINTHICKNESSTOWARDTHESHANK,INCREASINGTHERIGIDITYOFTHEDRILLANIMAGINARYLINETHROUGHTHECENTEROFTHEDRILLFROMENDTOENDISTHEAXISTHEDRILLMUSTROTATEEVENLYABOUTTHEAXISATALLTIMESSPECIALDRILLSSPECIALDRILLSARENEEDEDFORSOMEAPPLICATIONSTHATANORMALHIGHSPEEDINDUSTRIALOPERATIONSOTHERTYPESOFSPECIALDRILLSGENERALPURPOSEDRILLCANNOTACCOMPLISHQUICKLYORACCURATELYARELEFTHANDDRILL,SILVERANDDEMING,SPOTTING,SLOWSPIRAL,SPECIALDRILLSCANBETWISTDRILLTYPE,STRAIGHTFLUTEDTYPE,ORFASTSPIRAL,HALFROUND,DIE,FLAT,ANDCOREDRILLSTHEGENERALSPECIALFLUTEDSPECIALDRILLSCANBEKNOWNBYTHEJOBTHATTHEYPURPOSEHIGHSPEEDDRILL,WHICHISTHECOMMONTWISTDRILLUSEDAREDESIGNEDFOR,SUCHASAIRCRAFTLENGTHDRILLS,WHICHHAVEANFORMOSTFIELDANDMAINTENANCESHOPS,CANBEREGROUNDANDEXTENDEDSHANKSPECIALDRILLSAREUSUALLY第10页共35页USEDINADAPTEDFORMOSTSPECIALDRILLINGNEEDSSHARPENINGTWISTDRILLSTWISTDRILLSBECOMEDULLANDMUSTBERESHARPENEDTHEPREFERREDMETHODOFRESHARPENINGATWISTDRILLISWITHTHEDRILLGRINDINGMACHINE,BUTTHISMACHINEISNOTALWAYSAVAILABLEINFIELDANDMAINTENANCEUNITS,SOTHEOFFHANDMETHODOFDRILLSHARPENINGMUSTBEUSEDFIGURE410THEOFFHANDMETHODREQUIRESTHATTHEOPERATORHAVEAKNOWLEDGEOFTHEDRILLINGGEOMETRYFIGURE411ANDHOWTOCHANGEDRILLANGLESASNEEDEDFORANYDRILLINGJOBSEETABLE42INAPPENDIXATOOLSNEEDEDAREAUTILITYORBENCHGRINDERWITHADRESSEDWHEELANDADRILLPOINTGAGEFIGURE412ORPROTRACTORHEADONTHECOMBINATIONSQUARETHEDRILLPOINTGAGEISSETAT59ANDADJUSTEDALONGTHESTEELRULETOFITTHEDRILLTOBESHARPENEDTHECUTTINGLIPSMUSTBEOFTHESAMEANGLE,THELIPCLEARANCEANGLEMUSTBEWITHINASPECIFICDEGREERANGE,ANDTHECUTTINGLIPSMUSTBEOFANEQUALLENGTHTHEREARESEVERALBASICCHARACTERISTICSTHATALLTWISTDRILLSMUSTHAVETOCUTPROPERLYTHEFOLLOWINGWILLCOVERTHOSECHARACTERISTICS第11页共35页PRECHECKBEFORESHARPENINGATWISTDRILL,THEOPERATORMUSTCHECKTHECONDITIONOFTHEDRILLFORCHIPPEDANDCRACKEDLIPSOREDGESTHATMUSTBEGROUNDOFFDURINGTHESHARPENINGPROCESSTHEOPERATORMUSTALSOCHECKTHEREFERENCESFORTHEPROPERLIPANGLEANDLIPCLEARANCEANGLEFORTHEMATERIALTOBEDRILLEDAFTERSETTINGUPTHEBENCHGRINDERFOROFFHANDDRILLSHARPENING,THEOPERATORASSUMESACOMFORTABLESTANCEINFRONTOFTHEGRINDINGWHEELTOSHARPENTHETWISTDRILLTHESUGGESTEDMETHODISTOGRINDTHELIPANGLEFIRST,THENCONCENTRATEONGRINDINGTHELIPCLEARANCEANGLE,WHICHWILLTHENDETERMINETHELIPLENGTHTHEUSUALLIPANGLEISANINCLUDEDANGLEOF11859X2FIGURE413,WHICHISTHELIPANGLEOFGENERALPURPOSEDRILLSUSETHEDRILLPOINTGAGEFREQUENTLYTOCHECKLIPANGLEANDLIPLENGTHWHENGRINDING,DONOTALLOWTHEDRILLTOBECOMEOVERHEATEDOVERHEATINGWILLCAUSETHEDRILLEDGESTOBECOMEBLUEWHICHISANINDICATIONTHATTHEDRILLSTEMPERHASBEENLOSTTHEBLUEAREAMUSTBEGROUNDCOMPLETELYAWAYTOREESTABLISHTHEDRILLSTEMPERIFADRILLBECOMESTOOHOTDURINGSHARPENING,THELIPSCANCRACKWHENDIPPEDINTOCOLDWATERORCOOLANT第12页共35页DRILLPOINTWHENGRINDINGTHELIPANGLE,USETHEDRILLPOINTGAGEANDGRINDONELIPPERFECTLYSTRAIGHTANDATTHEREQUIREDANGLEUSUALLY590THENFLIPTHEDRILLOVERANDGRINDTHEOTHERLIPONCETHEANGLEISESTABLISHED,THENTHELIPCLEARANCEANGLEANDLIPLENGTHCANBEGROUNDIFBOTHLIPSARENOTSTRAIGHTANDOFTHESAMEANGLE,THENTHECHISELEDGEFIGURE414WILLNOTBEESTABLISHEDITISITIMPORTANTTOHAVEASHARPANDCENTEREDCHISELEDGEORTHEDRILLWILLNOTROTATEEXACTLYONITSCENTERANDTHEHOLEWILLBEOVERSIZEDIFTHEDRILLPOINTISTOOSTEEP,THEDRILLWILLREQUIREMOREPOWERANDCUTSLOWLYWHENTHEANGLESOFTHECUTTINGLIPSAREDIFFERENT,THENTHEDRILLWILLONLYHAVEONELIPCUTTINGASITREVOLVESTHEHOLEWILLBEOVERSIZEDANDTHEDRILLWILLWEARVERYRAPIDLYWHENBOTHTHEANGLESANDTHELENGTHOFTHEANGLESAREINCORRECT,THENEXCESSIVEWEARISPUTONBOTHTHEDRILLANDMACHINE,WHICHWILLRESULTINPOORWORKMANSHIPFIGURE415第13页共35页CLEARANCEANGLEWHENGRINDINGTHELIPCLEARANCEANGLE,FIGURE413,RELIEFMUSTBEGIVENTOBOTHCUTTINGEDGESALLOWINGTHEMTOENTERINTOTHEWORKPIECETODOTHECUTTINGGENERALPURPOSEDRILLSHAVEACLEARANCEOF8TO12THECHISELEDGEOFACORRECTLYGROUNDDRILLSHOULDBEATANANGLEOFABOUT45WITHTHELINEOFTHECUTTINGEDGESTHEANGLEOFTHECHISELEDGETOTHELIPSISAGUIDETOTHECLEARANCEFIGURE416TOOMUCHCLEARANCEWILLCAUSETHEDRILLTOBREAKDOWNBECAUSEOFINSUFFICIENTSUPPORTOFTHELIP,ANDTHEREWILLNOTBEENOUGHLIPTHICKNESSTOCARRYAWAYTHEGENERATEDHEATTOOLITTLECLEARANCEWILLRESULTINTHEDRILLHAVINGLITTLEORNOCUTTINGEDGES,ANDTHEINCREASEDPRESSUREREQUIREDTOFEEDITINTOTHEHOLEWILLCAUSETHEDRILLTOBREAKBYLOOKINGSTRAIGHTONTOTHECUTTINGTIPOFTHEDRILL,THEOPERATORCANSEEIFTHECHISELEDGEISCORRECTIFTHECHISELEDGEISCORRECTAT45TOTHELIPS,THENITISANINDICATIONTHATTHELIPCLEARANCEANGLEISCORRECTANINCORRECTCHISELEDGEISUSUALLY第14页共35页PRODUCEDBYHOLDINGTHEDRILLATANINCORRECTANGLETOTHEWHEELFIGURE417WHENGRINDINGAGOODGUIDEISTOHOLDTOTHEGROUND,ANDMAKESLIGHTADJUSTMENTSRAKEANGLETHEANGLEBETWEENTHEFLUTEANDTHEAXISTHEDRILLPARALLELOFTHEDRILLTHATFORMSTHECUTTINGEDGEISKNOWNASTHERAKEANGLEFIGURE41830BEINGTHEMOSTCOMMONDRILLSUSEDONARMORPLATEOROTHERVERYHARDMATERIALSNEEDAREDUCEDRAKEANGLETOINCREASETHESUPPORTBEHINDTHECUTTINGEDGESOFTMATERIALS,LIKEBRASSANDBRONZE,ALSOUSEAREDUCEDRAKEANGLETOPREVENTTHEDRILLFROMGRABBINGTHERAKEANGLEPARTIALLYGOVERNSTHETIGHTNESSWITHWHICHTHECHIPSCURLANDTHEAMOUNTOFSPACETHEYOCCUPYIFTHERAKEANGLEISTOOSMALL,THELIPSMAYBETOOTHINANDBREAKUNDERTHESTRAINOFDRILLINGTOOLARGEOFARAKEANGLEMAKESTHEDRILLCHATTERANDVIBRATEEXCESSIVELYTHEWEBOFADRILLISMADETHICKERTOWARDTHESHANKTOSTRENGTHENTHETOOLINSMALLERSIZEDRILLS,THEDIFFERENCEISNOTNOTICEABLE,BUTINLARGERDRILLS,WHENTHEPOINTISGROUNDBACKBYREPEATEDSHARPENING,THETHICKNESSOFTHEWEBBECOMESGREATERANDTHECHISELEDGEOFTHEDRILLBECOMESWIDERTHISCAUSESTHECHISELEDGETOSCRAPEONTHEBOTTOMOFTHEHOLEANDREQUIRESEXCESSIVEPRESSURETOBEAPPLIEDTOTHEDRILLTHISCANBECORRECTEDBYTHINNINGTHEWEBFIGURE419THEPOINTISGROUNDTHINNERONATHINGRINDINGWHEELWITHAROUNDEDFACETOFITINTOTHEFLUTEANEQUALAMOUNTOFMETALSHOULDBEGROUNDFROMEACHFLUTE第15页共35页DRILLGRINDINGMACHINESDRILLGRINDINGMACHINESFIGURE420MAKETHEACCURATEGRINDINGOFALLTYPESANDSIZESOFDRILLSANEASYJOBCOMPARATIVELYLITTLESKILLISREQUIREDTOSHARPENDRILLSWITHTHESEMACHINESWHILEFOLLOWINGTHEOPERATINGINSTRUCTIONS第16页共35页THEYAREPARTICULARLYVALUABLEWHENALARGENUMBEROFTHESAMEGENERALTYPEOFDRILLSISTOBESHARPENEDTWOBASICDESIGNSFORTHEBENCHTYPEDRILLGRINDINGMACHINESAREAVAILABLEBOTHPERFORMTHESAMEOPERATIONSBUTUSEDIFFERENTDRILLHOLDINGDEVICESTHECAPACITYOFTHESEMACHINESISSTATEDINTHE