机械制造技术基础课件-chapter4-section3(new)

4.3Holemakingmachinetoolandcuttingtool•Drillingmachine(钻床)•Boringmachine(镗床)•Broachingmachine(拉床)UsuallyusedholemakingmachinetoolsUsuallyusedholemakingcuttingtools•Twistdrill(麻花钻)and“massesdrill”(群钻)•Coredrill(扩孔钻)•Reamer(铰刀)•Boringcutter(镗刀)•Broachingcutter(拉刀)4.3.1DrillingmachinesDrillingmachinesandboringmachinescanbothenlargeandfinishcuttingofholesfromasmallfractionofamillimetretohundredsofmillimetresindiameter.Drillingmachinesareusedforroughdrillingholes.Maintypes:Vertical(立式）、Radial（摇臂）、Deepholedrills（深孔）.ThepictureshowsatypicalVerticalDrillingmachines.worktableBaseTheheadstockcolumn主轴箱立柱工作台底座RadialdrillpressMethodsofMachiningoperationsFig3.29扩孔鍃孔铰孔深孔钻4.3.1Drillingmachines4.3.2BoringmachineBoringistheoperationthatenlargesapre-existedinternalhole.Severalmachineshavebeendevelopedthatarespeciallyadaptedtoboringwork..Maintypesofboringmachines:Horizontalboringmachine、Jigboringmachinesandhighaccurateboringmachine鞍形工作台镗\钻\铣头镗杆支撑轴承Boringmachine(镗床)Performance:bigsize,highaccurate,differentsurfaces,highaccuraterelativeposition.Mainmotion:rotationoftheboringcutterfeedmotion:cutterorworkpieceJigboringmachine(坐标镗床）:Veryhighaccurateposition.positionaccuracyisbetween0.002~0.01mmDiamondboringmachinediamondboringcuttersused.JobsdonebyhorizontalboringmachineMethodofHorizontalboringmachineoperations4.3.3Drillingtools(1)TwistdrillTipangle—formedbytwoplanesparallelwiththetwomaincuttingedgesChiseledge—centeredgelinkingthetwomaincuttingedgesThemaingeometryfortwistdrillare:thehelicalangle(24~30)螺旋角,thetipangle2(118~130)锋角,rakeangle前角,reliefangle后角andChiseledgeangle横刃斜角Lipreliefangle钻缘后角Cuttingperformancesaffectedbygeometry•Helicalangle:itistheaxialrakeangle,βγfforstandardtwistdrillβ=18°~30°。drillbronzeorsoftcopper：β=10°~17°lightalloy,redcopper：β=35°~40°highstrengthsteel,castironβ=10°~15°AxialforceandmomentCuttingeasyStrengthandheatoffToollifeβTipangleCuttingedgelengthUnitcuttingedgeforceandaxialforceTipstrengthTwistmomentHeatoffToollife1OrdinaryTwistdrills（麻花钻）Themaingeometryfortwistdrillare:thehelicalangle(24~30),thetipangle2(118~130),rakeangle,reliefangleandwedgeinclinationangleDifferenttypesoftwistdrillsadapted2AdaptedtwistdrillsThequalityofsurfacemachinedbytwistdrillTheaccuracy:IT11-IT12Theroughness:50~12.5mTherangeofdiametermachined:0.1~80mmMaterial:2Adaptedtwistdrill——MassesDrillQuestion:whatarethemaindisadvantagesoftraditionaltwistdrill?Whatchangeshappenedon“qunzuan”Ordinarytwistdrill•三尖七刃锐当先，月牙弧槽分两边，外刃再开分屑槽，横刃磨低窄又尖。•(2)Centerdrill(中心钻）Centerdrillisusedtomachinethecenterholeofaworkpiece.Fig3.38showstwokindsofcenterdrilling.centerdrilling(3)Deepholedrilling(gundrilling,深孔钻)Definitionofdeephole:WhenL/disbetween5~20Method:lengthenthetwistdrillWhenL/Disbiggerthan20,Method:SpecializeddeepholedrillingmachineAccuracy:usuallyreachIT8-IT10,sometimesIT6-IT9(Specialdesign)Roughness:3.2~0.8mFluidinChipout(4)coredrill(IT10-IT11,Ra6.3~3.2)（扩孔钻）Accuracy:IT10-IT11Roughness:6.3~3.2mSize:10~80mmIntegraltypeCarbidetippedtypeRotationaltype(5)Counterboringdrill(锪钻）(6)Reamer(IT6~IT11,Ra1.6-0.2)铰刀FigstructureandgeometricalparametersofreamerWorkingpartneckshankCuttingpartGuidetapercalibratingpartIncludeCylindricalandconepartTheaccuracywithreamingcanreachIT6~IT8,theroughnesscanbe1.6~0.4m,suitableforfinishorsemi-finishmachiningDiscussion:Whycanthereamingmethodimprovethemachinedqualities?variousreamershandlefixedtype(手动式）handleadjustabletype（可调整手动式）shelltype（套式）Carbidetippedtype（镶硬质合金齿）variousreamers(7)boringtool（a）（b）（c）single-bladeboringtoolAdvantage:simple,easytomake,generalpurpose,oftenusedCanyoutellthedisadvantage?DoublebladeboringtoolMaterial:Floatingtype:why?Accuracy:IT6-IT7Roughness:canbe0.8mQuestion:comparedtosingletype,whatarethemainadvantagesofdoublebladeboringtool?Fig3.46examplesforvariousbroachingsurface(8)BroachingcutterDiscussion:couldyoutelltheadvantageofbroachingmethod?Whatisthedisadvantage?structureofholebroachingcutterDiscussion:whycanthebroachingmethodachievehighaccuracy?1－head(头部)；2－neck(颈部)；3－conetransition(过渡圆锥)；4－frondleadingpart(前导部)5－cuttingpart(切削部)；6－calibratingpart(校准部)；7－rearleadingpart(后导部)；8－tail(尾部)Broachinglayerbylayer(分层拉削）Broachingblockbyblock(分块式拉削）Broachingbymixingtwomethods(综合式）