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CuttiingToolGeometrgyShapeofcuttingtools,particularyntheangles,andtoolmaterialareveryimportantfactors.Anglesdeterminegreatiynotonlytoollifebutfinishqualityaswell.generalprinciplesuponwhichcuttingtoolanglesarebaseddonotdependontheparticulartool.basically,thesameconsiderationsholdturewhetheralathertool,amillingcutter,adrill,orevenagrindingwheelarebeingdesigned.Since,however,thelathe(turnign)tool,depictedinFig.Toolfeatureshavebeenidentifiedbymantnames.Thetechnicalliteratureisfullofconfusingterminology.Thusintheattempttoclearpexistingdisorganizedconceptionsandnomenclature,theAmericanSocietyofMechanicalEngineerspublishedASAStandardB5-22-1950.Whatfollowsisbasedonit.Asingle-pointtoolisacuttingtoolhavingonefaceandonecontinuouscuttingedge.ToolanglesidingtifiedinFig.18.2areasfollows:Toolangle1,onfrontview,istheback-rakeangle.Itistheanglebetweenthetoolfaceandalineparalleltothebaseoftheshankinalongitudinalplaneperpendiculartothetoolbase.Whenthisangleisdownwardfromfronttorearofthecuttingedge,therakeispositive；whenupwardfromfronttoback,therakeisnegative；Thisangleismostsgnnificantinthemachiningprocess,becauseitdirectlyaffectsthecuttingforce,finesh,andtoollife.Theside-rakeangle,numbered2,measurestheslopeofthefaceonacrossplaneperpendiclartothetoolbase.It,also,isanimportantangle,becauseitdirectschipflowtothesideofthetoolpostandpermitsthetooltofeedmoreeasilyintothework.Theend-reliefangleismeasuredbetweenalineperpendiculartothebaseandtheendflankimmediatelybelowtheendcuttingedge；itisnumbered3inthefigure.Itprovidesclearancebetweenworkandtoolsothatitscrtsurfacecanflowbywithminiumrubbingagainstthetool.Tosavetime,aportionoftheendflankofthetoolmaysometimesbeleftunground,havingbeenpreviouslyforgedtosize.Insuchcase,thisend-clearanceangle,numbered4,measuredtotheendflanksurfacebelowthegroundportion,wouldbelargerthanthereliefangle.Oftentheendcuttingedgeisobliquetotheflank.Thereliefangleisthenbestmeasuredinplanemormaltotheendcuttingedgeangle.Reliefalsoexpressedasviewedfromsideandendofthetool.Theside-reliefangle,indicatedas5,ismeasuredbetweenthesideflank,justbelowthetuttingedge,andalinethroughthecuttingedgeperpendiculartothebaseofthetool.Thisclearancepermitsthetooltoadvancemoresmoothlyintothtwork.Angle6istheend-cutting-edgeanglemeasuredbetweewtheendcuttingedgeandalineperpendiculartothesideofthetoolshank.fThisanglepreventsrubbingofthecutsurfaceandpermitslongertoollife.Theside-cutting-edgeangle,numbered7,istheanglebetweenthesideofthetoolshank.Thetruelengthofcurisalongthisedge.Thustheangledeterminesthedistributionofthecuttingforce.Thegreatertheangle,thelongerthetoollife；butthepossibilityofchatterincreases.Acompromisemust,asusual,bereached.Thenoseangle,number8,istheanglebetweenthetwocomponentcuttingidges.Ifthecornerisroundedoff,thearcsizeisdefinedbythenoseradius9.Theradiussizeinfluencesfinishandchatter.刀具的几何参数刀具的形状（特别是其角度）和材料是刀具的两个非常重要的因数。刀具的角度不仅在很大程度上决定可刀具的寿命《而且也在很大程度上决定了加工的表面的质量。刀具的角度设计有其一般性原则，它并不因某中特殊刀具而变。车刀，铣刀，钻头甚至是砂轮的设计，所要考虑的因素基本相同。刀具外形最易观察，我们即以此为例来讨论刀具的集合参数。刀具特征名目繁多，技术文献中术语使用也很混乱。为了澄清混乱的概念和术语，美国机械工程师协会颁布了ASA标准B5—22-1950，本文的术语即以此为依据。单尖刀具是指只有一个前刀面和一条连续切削刃的刀具各个角度含义如下：主视图中的角度I为背前角，它是在垂直于刀具基面的纵向剖面内的平行于基面的一条直线与前刀面之间的夹角。如该角后倾，则为正角，否则为负角。背面角对加工过程影响很大，它直接影响刀具的切削力，表面光洁度以及刀具耐用度。角度2为侧前角，它是刀具前刀面在垂直于刀具基面的横向剖面内的倾斜角。侧前角也是一个重要的几何角度，它能把切削引向刀架的一侧，并能使进给更加容易。端后角是刀具基面的垂线与紧靠端切削刃下的端后刀面之间的夹角。端后角保证了在工件和刀具之间的摩擦。为了节省磨刀时间，刀具端后刀面的一部分有时可以直接锻造成型，而不需要进行磨削。在这种情况下，从刃磨部位下面的端后刀面量出的后角比端后的角大。通常端切削刃与端后面是斜交的，因此，端后角最好是在与端切削刃相垂直的平面内进行测量。后角也可以从刀具的侧面和端面来观测。角度5为侧后角，它是紧靠切削刃下面的侧后刀面与通过切削刃并垂直与刀具基本面的直线之间的夹角。侧后角能使刀具较平稳的切入工件。角度6为端切削刃角，它是端切削刃和垂直与刀具柄侧面的直线之间的夹角。该角减少了刀具和已加工表面之间的摩擦，延长了刀具的使用寿命。角度7为侧切削刀角，它是侧切削刃和垂直于刀具柄侧面的直线之间的夹角。由于刀具切削长度是沿着此切削刃的，因此，侧切削刃角决定了切削力的分布。该角度越大，刀具寿命越长，但颤震的可能性也随之增加。设计时，这面反面的因素要兼顾。角度8是刀尖角，它是两条切削刃之间的夹角。刀尖采用圆弧过渡时，圆弧的尺寸对表面光洁度及颤振有影响。

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