机械制造专业本科毕业设计外文翻译

英文原文名FormingandDieDesign中文译名成形工艺及模具设计英文原文版出处：《模具设计与制造专业英语》刘建雄王家惠廖丕博主编北京大学出版社2006年3月第1版译文：金属加工是工程科学的一个分支,它的制造金属部件和结构通过塑性成形过程加工、焊接和铸造来完成。这局部着重于在金属冲压成形工艺及其模具设计加工。冲压主要用于薄板成形,它不仅可以用在金属成形,而且也可以用在非金属形成。在冲压成型,模具的作用下,内力变形发生在板上。当内力到达一定程度时，相应的塑性变形在空白区域发生。因此一定形状的变形局部，是生产规模的特性。冲压是通过冲模在压力机上对金属板料施加压力使其产生塑性别离或变形从而得到满足使用要求的加工方法，具有较高的生产效率。由于其操作简单易于实现冲压机械化和自动化。生产冲压件的模具可以用来生产复杂的局部，所以可以用于其他加工方法难以加工的工件。冲压件在使用中一般无需进一步加工。通常冲压过程中不需加热。因此，它不仅节约了材料，也节约了能量。此外，冲压件具有重量轻、刚度大的特点。生产中为满足冲压零件形状、尺寸、精度、批量、原材料性能等方面的要求，采用多种多样的冲压加工方法。概括起来冲压加工可以分为别离工序与成形工序两大类。别离工序是在冲压过程中使冲压件与板料沿一定的轮廓线相互别离的工序。对别离的横截面的外表质量必须满足一定的要求。成型工序包括弯曲、拉深、翻边、胀形、缩口、挤压、扩口等，是毛坯在不被破坏的条件下产生塑性变形，形成所要求的形状和尺寸精度的制件。冲压工艺广泛应用在表1-1列出。表1-1的冲压工艺分类及其特征1.2落料冲孔模冲裁冲裁是利用模具使板料的一局部另一局部沿一定的轮廓形状别离的冲压方法，包括落料、冲孔、切断、修边、切舌、剖切等工序，其中落料和冲孔是最根本的冲裁工序。落料和冲孔是金属片沿一封闭轮廓处别离的过程。经落料和冲孔板分为两局部。沿封闭轮廓处别离，且别离的目的是为了获得封闭轮廓形状以外内的局部〔即落下来的是工件〕那么为落料，如果是为了得到封闭轮廓形状以外的局部〔即落下的是废料，带孔的是工件〕那么为冲孔。落料和冲孔的模具结构是相同的，通常落料和冲孔的变形过程也是相同的。通过冲裁工艺，可以生产成品与半成品的变形过程。在图1-1垫环显示的情况下，得到的工件是Φ22毫米的圆叫落料，它的冲裁变形过程在中。冲裁变形过程冲裁时把板料固定在凹模上，凸模向下移动与板料接触并开始冲裁。由于凸、凹模之间存在间隙，凸模对凹模和板料的力主要集中在凸模的边缘。冲裁变形过程显示在图2中。如果模具间隙适宜，在凸模和凹模的作用下，变形过程经历三个阶段，即，弹性变形，塑性变形和断裂别离阶段1.弹性变形阶段在凸模压力下，材料首先产生弹性压缩，产生拉伸和弯曲变形，在这一阶段，内部应力不超过弹性极限而不发生塑性变形，卸载压力时变形恢复。2.塑性变形阶段凸模继续下压，当材料内的应力满足屈服准那么时便开始进入塑性变形阶段，在凸模和凹模的压力下，对胚料的外表进行压缩，由于凸模、凹模之间的间隙，使板料受到弯矩的的作用，产生弯曲变形，使凹模上的板料翘曲，两者的过渡处〔凸凹模刃口处〕形成圆角。当凸模挤入板料的深度增大，材料的塑性变形程度增大，变形区材料硬化加剧。当刃口附近的材料由于拉应力作用出现裂纹时，冲裁变形抗力到达最大值，塑性变形结束。3.断裂别离阶段凸模的继续下压，顶部和底部的裂缝逐渐延伸到金属板的内层，当上下裂纹重合时，板料便被剪断别离，完成冲裁。在冲裁过程中的断裂带的力量平衡图1-3所示；F1、F2是凸、凹模对板料的垂直作用力，F3、F4是凸凹模对板料的侧压力；。μF1、μF2是凸凹模断面与板料间的摩擦力，μF3、μF4μ是凸凹模侧面与板料间的摩擦力；F1和F2的μ方向与凸模和凹模之间的间隙有关。冲裁力的分析说明，F3和F4侧向压力必须小于垂直压力F1和F2；而裂纹扩展更容易发生在压力小的区域。因此，冲裁时初始裂纹发生在凹模的侧面。裂纹萌生和开展通过电子显微镜扫描说明，当凸模向下挤压的深度进入板料到达20%时，裂纹发生在凸模和凹模刃侧外表，然后在顶部和底部的裂纹迅速扩展，当两个裂纹重合，毛坯剪切和断裂过程结束。冲裁件质量冲裁件的质量主要是指割断面状况、尺寸精度和形状误差。工件的断面质量是决定冲裁工艺是否成功一个重要因素。如图，冲裁件断面可分为四个区域：蹋角带、光亮带、断裂带和毛刺。由于凸凹模刃口对板料进行塑性剪切而形成光亮带，由于同时受到模具侧面的挤压力该区域不仅光亮且与板平面垂直，是断面上质量最好的区域，当间隙适宜时，光亮带约占板料厚度的1/2~1/3。断裂带形成于冲裁变形的断裂阶段，是裂纹向板内部扩散的结果，是冲裁断面上质量最差的局部，不仅粗糙且带有斜度。蹋角带是由于刃口附近的材料产生拉伸弯曲的结果，材料塑性越好，蹋角带约大。毛刺形成于断裂别离阶段，形成的毛刺是细长的且附在工件上。影响断面质量的因素很多，四个区域的比例〔蹋角带、光亮带、断裂带和毛刺〕随冲裁条件的变化而变化，如工件材料、冲床、模具和设备等。图1-5显示影响冲裁件断面质量的主要因素，图1-6显示影响冲裁件的尺寸精度的因素。研究分析说明，凸模和凹模之间的间隙是影响外表质量和冲裁工件尺寸精度的重要因素，提高冲裁工件的外表质量，是研究间隙对机制的影响具有重要的意义，从而找到计算凸模和凹模之间间隙的最正确的方法。冲裁模总体结构设计1.冲裁模典型结构〔1〕单工序模单工序模也叫简单模，是指压力机的一次行程只完成一道冲压工序的模具。其结构简单〔见图1-7中所〕，所以它可以容易地制造，它是适用于小批量生产。〔2〕级进模压力机在一次行程下在不同工位完成多道工序的模具叫级进模，如图1-8所示。条料送进时，定位销2在冲孔之前定位，冲孔凸模4向下移动完成冲孔，产生工件8。当冲孔凸模返回时，凸模4上的板料通过卸料板6卸下废料7，胚料前进一个步距，然后开始第二个落料，重复以上步骤，板料的进距是通过定位销来控制的。〔3〕复合模复合模是只有一个工位，并在压力机的一次行程过程中完成两道或两道以上的冲压工序的模具称为复合模，如图1-9所示。该复合模的主要特点是有一个凸凹模。凸模1的外圆冲裁凸模切边，而内孔是拉深模。凸模1跟滑块向下移动，冲裁过程是通过冲压模1和冲裁模4来完成的，冲裁工件的拉深凸模2推开工件，然后拉深模向下移动进行拉深。推杆5和卸料板3卸下拉深件9时，滑块返回。复合模适用于大批量生产和高精度的冲裁。2.凸模和凹模凸模有三种国家标准的凸模，如图1-10，在工作中应确定凸模的尺寸。一种圆形凸模采用D=1.1~30.2毫米，B型为D=3~30.2毫米，快速变化的圆凸模为D=5~29毫米。固定在凸模固定板的圆形穿孔，孔底采用过渡配合H6为A和B类圆形凸模，基孔间隙配合H6为快速变化的圆形凸模。该凸模长度应该由模具结构确定。使用的固定卸料板和导料板〔见1-11〕，该冲头长度L：L=H1+H2+H3+H式中，H1是凸模固定板厚度；H2是卸料板的厚度；H3是导料板厚度；H是由凸修模量及凸模进入凹模的深度〔0.5~1毫米〕，一般去经验值〔10~20毫米〕包括模具闭合时凸模固定板与卸料板之间的平安距离。非标准凸模及其固定模式如图1-12所示，同一模具凸模之间的距离很小，铆接结构可用于圆形凸模图1-12〔a〕，一个结构通常用于小冲孔如图1-12〔b〕，快速更换式冲模一般用于易磨损的冲孔如图1-12〔c〕，；对非圆凸模，如果它的大小是大了一点，它可以直接通过螺栓固定在模套上，而不是通过固定板、销钉、螺栓、定位槽固定如图1-12〔d〕；如果凸模的工作局部是非圆形的，圆形台阶结构用于紧固局部，一个停止计应加如图1-12〔e〕。对于小的冲孔，也可以由低熔点合金固定在凸模固定板，无机环氧树脂胶粘剂，如图1-13所示。〔2〕凹模冲裁模的结构形式如图1-14。图1-14〔a〕和图1-14〔b〕为直壁切边模具。切削刃的强度很高，其工作局部的尺寸保持不变后修补和制造方便。它适用于冲压工件形状复杂或高公差要求的工件，但在这种情况下，工件废料易积累在切割边缘的孔内，因此增加材料的扩展性和反冲力使孔壁穿孔。切削刃的磨损形式呈倒锥形状，这可能会引起工件从孔开口跳到模具外表，造成操作困难。该图1-14〔a〕模型切削刃是适用于非圆工件，且图1-14〔b〕模型适用于圆形工件，使工件或废料需要被喷出的模具，或复合冲裁模。图1-14〔c〕和图1-14〔d〕为锥形切削刃模具，工件或废料容易落下。从模孔，工件或废料不会积累在切割边缘的孔内。摩擦和扩大的孔壁上施加力小，因此穿模以及模具修补操作量小。但是切削刃的强度低一点，切削刃的修补后的尺寸增加，但一般工件尺寸对模具寿命的影响小。用锥形切削刃模具适用于冲压形状简单的薄板工件和较低的公差要求的工件。冲裁工具根据冲裁原理相对于另一个导向型的工具，分为导料板、导料销、侧压装置。一个自由的冲裁工具的结构类似于图1-15中的显示。模具的剪冲裁元件不会遵循各自的引导；对模具的导向一般是由压力机滑块引导控制。一个质量好的冲压件和导向结构可以在引导下负载。冲裁工具在低本钱的根底上，设计简单冲裁模具。因此适合用于小批量的生产。这很难在模具初始设置时调整周围均匀的间隙，这可能会导致较大的磨损，特别是在小的厚度≤1毫米的板，间隙可以为0.01毫米。在一个引导工具设置的情况下〔图1-16〕落料冲模由导料板引导。建立加工位置误差可以防止。冲压的微弱导向效果由于轴承间隙和C型压力机角偏转通过引导冲减。对凸模导向的另一个优势是长臂弯曲阻力。导向板也被用作一个卸料板。一个冲裁单元作为一个导向性的原理可能会带来一些缺点。如果不采取适当措施，材料颗粒粘模或凸模会导致更快的磨损。同时对大型复杂模具精确制导孔加工困难，本钱更高。在案件的支柱引导冲裁模具〔图1-17〕的导向作用和剪切彼此分开。支柱引导使这个工具准确，与其他原理的减少刀具磨损相应的设计。不需要考虑轴承间隙误差，在设置支柱引导的高精度模具，设置工具简单、耗时少。支柱引导工具，如引导板的模具，可以有助于轴承负荷间隙和冲压的角偏转减少缺陷。根本支柱引导被视为工具来帮助建立和制造精确的工具。通常用支柱引导采取强侧推力引起的非中心加载的工具和倾斜运动的G型机不允许位移过大。因此，支柱引导不是不准确的按下引导替代和较小的刚性压力机。他们有不同的导柱，球轴承导轨负载下非常准确，他们之间会有小的摩擦，因此用快速开关的情况下，充分的润滑机器。导柱导向工具也可以配备为材料的活动导向板。导向板安装在立柱上，模具体一般是在工具上的弹簧支撑。该设计一般用于冲裁薄板冲裁片保证平整度。凸模可引导他直到它接触板料。这就要求在板的导向孔非常精确的制造有双导向，即在导柱导向工具和在导向板的凸模间导向。双向导柱一般是制造本钱比拟高。英文原文Chapter1StampingFormingandDieDesign1.1IntroductionMetalprocessingisabranchofengineeringscience,whichdealswiththemanufacturingofmetallicpartsandstructuresthroughtheprocessesofplasticforming,machining,weldingandcasting.Thispartfocusesonthestampingformingtechnologyanditsdiedesigninmetalprocessing.Stampingismainlyusedinsheetplateforming,whichcanbeusednotonlyinmetalforming,butalsoinnon-metalforming.Instampingforming,undertheactionofdies,theinnerforcedeformingtheplateoccursintheplate.Whentheinnerforcereachesacertaindegree,thecorrespondingplasticdeformationoccursintheblankorinsomeregionoftheblank.Thereforethepartwithcertainshape,sizeandcharacteristicisproduced.Stampingiscarriedoutbydiesandpress,andhasahighproductivity.Mechanizationandautomatizationforstampingcanberealizedconvenientlyowingtoitseasyoperation.Becausethestampingpartisproducedbydies,itcanbeusedtoproducethecomplexpartthatmaybemanufacturedwithdifficultybyotherprocesses.Thestampingpartcanbeusedgenerallywithoutfurthermachining.Usually,stampingprocesscanbedonewithoutheating.Therefore,notonlydoesitsavematerialbutalsoenergy.Moreover,thestampingparthasthecharacteristicsoflightweightandhighrigidity.Stampingprocessesvarywiththeshape,thesizeandtheaccuracydemands,theoutputofthepartandthematerial.Itcanbeclassifiedintotwocategories:cuttingprocessandformingprocess.Theobjectiveofcuttingprocessistoseparatethepartfromblankalongagivencontourlineinstamping.Thesurfacequalityofthecross-sectionoftheseparatedpartmustmeetacertaindemand.Informingprocesses,suchasbending,deepdrawing,localforming,bulging,flanging,necking,sizingandspinning,plasticdeformationoccursintheblankwithoutfractureandwrinkle,andthepartwiththerequiredshapeanddimensionalaccuracyisproduced.ThestampingprocesseswidelyusedarelistedinTable1-1.Table1-1ClassificationoftheStampingProcessesandTheirCharacteristics1.2BlankingandPunchingDies1.2.1Cuttingisashearingprocessthatonepartoftheblankiscutfromtheother.Itmainlyincludesblanking,punching,trimming,partingandshaving,wherepunchingandblankingarethemostwidelyused.Blankingandpunchingaretheprocessestoseparatesheetmetalalongaclosingoutline.Afterblankingandpunching,theplateisseparatedintotwoparts.Punchingistopunchaneededholeinablankorworkpiece,andthematerialpunchedfromtheblankisthewaste,thatis,thepartoutoftheclosingoutlineistheworkpiece,andthepartintheclosingoutlineisthewaste.Oppositely,blankingistopunchaworkpieceorblankwithneededshapeintheplate,thatis,thepartintheclosingoutlineistheworkpiece.Thepartoutoftheclosingoutlineisthewaste.Thedeformationprocessandthediestructureareidenticalinbothblankingandpunching.Conventionally,bothblankingandpunchingarecalledblanking.Throughblankingprocess,finalproductaswellassemifinishedproductforotherformingprocesscanbeproduced.InthecaseofthecushionringshowninFig.1-1,theprocesstomakethecircleofΦ22mmiscalledblanking,andthattomaketheinsideholeofBlankingDeformationProcessBlankingDeformationProcessAblankingprocessinvolvesplacingtheblankonthedie,movingthepunchdownwardtodeformandseparatetheblankwiththeedgesofthepunchanddie.AclearanceZisexistedbetweenthepunchanddie.Theforcesofthepunchanddieapplyingontheblankaremainlyconcentratingontheedgesofthepunchanddie.BlankingdeformationprocessisshowninFig.1-2.Undertheactionsofthepunchanddiewithsharpcuttingedgesandanappropriateclearance,deformationprocessundergoesthreestages,namely,elasticdeformation,plasticdeformationandfractureseparatingstages.1.ElasticDeformationStageWhenthepunchcontactstheblank,thematerialiscompressed,resultingintensileandbendingelasticdeformation.Inthisstage,theinnerstresshasn’texceededtheelasticlimitoftheblankyet.Thedeformationwouldrecoverifunloadingisoccurred.2.PlasticDeformationStageWhenthepunchpressesfurtherdownwardontheblank,theinnerstressoftheblankreachesitsyieldstrength,theplasticflowandslidingdeformationbegintooccur.Underthepressureofthepunchanddie,thesurfaceoftheblankissubjectedtocompression,duetotheclearancebetweenthepunchanddie,theblankissubjectedtotheactionsofbendingandtensionsimultaneously,thematerialbeneaththepunchisbended,andthatabovethedieiscurledupwards.Circularanglesareformedinregions①and②duetobendingandtension,andindentationsappearinregions③and④.Whilethepunchsqueezefurtherintotheblank,theplasticdeformationandtheworkhardeninginthedeformationzoneincreasefurther.Whentheinnerstressoftheblanknearthecuttingedgereachesthestrengthlimitofthematerial,theblankingforcereachesitsmaximumandthecracksoccurintheblank,resultinginthedamageofthematerialandtheendoftheplasticdeformationstage(seeFig.1-2).3.FractureSeparatingStageWiththepunchsqueezingintotheblankcontinuously,thecracksatthetopandbottomextendtotheinnerlayerofthesheetmetalgradually,whenthetwocracksmeet,theblankiscut,andthentheprocessoffractureisended.EquilibriumofforcesintheshearingzoneduringblankingisshowninFig.1-3;whereFlandF2aretheactingforcesofthepunchanddieperpendiculartotheblankrespectively;F3andF4arethelateralpressuresofthepunchanddieexertingontheblankrespectively;μF1,μF2arethefrictionsontheendsurfacesofthepunchanddieactingontheblankrespectively;μF3,μF4arethefrictionsonthelateralsurfacesofthepunchanddieactingontheblankrespectively.ThedirectionsofμF1andμF2varywiththeclearancebetweenthepunchanddie.AnalysisoftheblankingforcesshowsthatthelateralpressuresF3andF4mustbesmallerthantheperpendicularpressuresF1andF2;andthatthecracksoccurandextendmoreeasilyintheareaofsmallpressure.Therefore,theinitialcrackoccursonthesidesurfaceofthedie.Observationoncrackinitiatinganddevelopingwithscanningelectronicmicroscopeshowsthatwhenthedepthofpunchsqueezingdownwardintothematerialreaches20%oftheblankthickness,thecrackoccursonthesidesurfaceofthepunchanddieedges,andthenthecracksatthetopandbottomextendrapidly.Whenthetwocracksmeet,theblankisshearedandtheprocessoffractureisended.BlankingWorkpieceQualityThequalityoftheblankingworkpiecemainlyreferstothequalitiesofthecuttingcross-sectionandworkpiecesurface,shapetoleranceanddimensionalaccuracy.Thecuttingcross-sectionqualityoftheworkpieceisanimportantfactortodeterminewhethertheblankingprocessissucceededornot.AsshowninFig.1-4,thecuttingcross-sectioncanbedividedintofourregions:thesmoothshearedzone,fracturezone,rolloverzoneandburrzone.Whenthepunchedgecutsintotheblank,theplasticdeformationoccursduetoextrusionbetweenthematerialandthesideofthecuttingedge,resultingintheformingofthesmoothshearedzone.Duetothecharacteristicofextrusion,thesurfaceofthesmoothshearedzoneissmoothandperpendicular,andistheregionwithhighestaccuracyandqualitywithinthecuttingcross-sectionoftheblankingworkpiece.Thethicknessratioofthesmoothshearedzonetothecuttingcross-sectionisabout1/2～1/3.Thefracturezoneisformedinthefinalstageofblanking,it’stheareawhereblankiscutoff,andthefracturesurfaceisformedwiththecracksexpandingcontinuouslyundertensilestress.Thesurfaceofthefracturezoneisroughandinclined,andisnotperpendiculartotheblank.Therolloverzoneisformedwhenthediepressesintotheblank.Thematerialnearcuttingedgeisembroiledanddeformed.Thebettertheplasticityofthematerial,thelargerwouldbetherolloverzone.Theburrofthecuttingcross-sectionisformedwhenmicro-cracksoccurduringblanking.Theformedburristhenelongatedandremainsontheworkpiece.Therearemanyfactorsaffectingthequalityofthecuttingcross-section.Theproportionofthethicknessofthefourzones(smoothshearedzone,fracturezone,rolloverzoneandburrzone)varieswithblankingconditions,suchasworkpiecematerial,punchanddie,equipment,etc.Fig.1-5showsthemainfactorsthataffectthequalityofthecuttingcross-sectionofblankingworkpiece.Fig.1-6showsthosefactorsaffectingthedimensionalaccuracyofblankingworkpiece.Theresearchandanalysisshowthattheclearancebetweenthepunchanddieisthemostimportantfactoraffectingthesurfacequalityandthedimensionalaccuracyoftheblankingworkpiece.Toincreasethesurfacequalityoftheblankingworkpiece,itisimportanttostudytheclearanceinfluencemechanism,soastofindamethodforcalculatingtheoptimalclearancebetweenthepunchanddie.BlankingandPunchingDies1.TypicalStructureofBlankingDie(1)SimpleDieThediethatonlyoneprocessiscarriedoutinonepressstrokeiscalledsimpledie.Itsstructureissimple(seeFig.1-7),soitcanbeeasilymanufactured.Itisapplicabletosmallbatchproduction.(2)ProgressiveDieThediethatseveralblankingprocessesarecarriedoutatdifferentpositionsofthedieinonepressstrokeiscalledprogressivedie,asshowninFig.1-8.Intheoperation,thelocatingpin2aimsatthelocatingholespunchedpreviously,andthepunchmovesdownwardstopunchbypunch4andtoblankbypunch1,thustheworkpiece8isproduced.Whenthepunchreturns,thestripper6scrapestheblank7fromthepunch4,theblank7movesforwardonestepandthenthesecondblankingbegins.Abovestepsarerepeatedcontinually.Thestepdistanceoftheblankiscontrolledbyastoppin.(3)CompoundDieThediethatseveralprocessesarecarriedoutatthesamediepositioninonepressstrokeiscalledcompounddie,asshowninFig.1-9.Themaincharacteristicofthecompounddieisthatthepart1isboththepunchandthedie.Theoutsidecircleofthepunch-die1isthecuttingedgeoftheblankingpunch,whiletheinsideholeisadeepdrawingdie.Whentheslidemovesdownwardsalongwiththepunch-die1,theblankingprocessisdonefirstbythepunch-die1andtheblankingdie4,theblankedworkpieceispushedbydeepdrawingpunch2,andthenthedeepdrawingdiemovesdownwardstocarryoutdeepdrawingoperation.Theejector5andthestripper3pushthedeepdrawnworkpiece9outofthediewhentheslidereturns.Thecompounddieissuitableformassproductionandhighaccuracyblanking.2.PunchandDie(1)PunchTherearethreekindsofstandardpuncheswithcircularformintheNationalStandard,asshowninFig.1-10.Whichkindofpunchshouldbeselectedisdeterminedbythedimensiondintheworkingportion.Atypecircularpunchisadoptedford=1.1~30.2mm,Btypeford=3.0~30.2mm,quick-changecircularpunchford=5~29mm.Tofixthecircularpunchonthepunchplate,thehole-basetransitionfith6isadoptedforAandBtypesofcircularpunches,andthehole-baseclearancefith6forthequick-changecircularpunch.ThelengthLofpunchshouldbedeterminedbythediestructure.Whenusingthefixedstripperandstockguide(seeFig.1-11),thelengthLofpunchis:L=H1+H2+H3+Hwhere,H1isthethicknessofthefasteningplateinmm;H2isthethicknessofthestripperinmm;H3isthethicknessofthestockguideinmm;Histheadditionallengthmainlydeterminedbythedepthofpunchenteringintothedie(0.5~1mm),thetotalwearingrepairingamount(10~15mm)andthesafedistancebetweenthestripperandpunchplatewhenthedieisintheshutstate(15~20mm).Thenon-standardpunchesandtheirfasteningpatternsareshowninFig.1-12.Whenthedistancebetweenpunchesinthesamedieisverysmall,arivetingstructurecanbeusedforthecircularpunch(Fig.1-12(a));ajacketstructureisusuallyusedforthesmallholepunching(Fig.1-12(b));thequick-changetypeisusedforthesmallpunchwhichisvulnerabletodamageduringblanking(Fig.1-12(c));forthenon-circularpunch,ifitssizeisabitlarge,itcanbefastenedtothediebolsterdirectlybybolts,pinsorboltsandlocationgrooveinsteadofthefasteningplate(Fig.1-12(d));iftheworkingportionofpunchisnon-circular,acircularstepstructureisusedinthefasteningportion,andastopgaugeshouldbeadded(Fig.1-12(e)).Forthesmallpunch,itcanalsobefastenedtothepunchplatebylow-meltingalloy,inorganicorepoxyresinadhesive,asshowninFig.1-13.(2)DieThepatternsofthediecuttingedgeareillustratedinFig.1-14.Fig.1-14(a)andFig.1-14(b)arethedieswiththestraightwallcuttingedge.Thestrengthofthecuttingedgeishigh,thedimensionofitsworkingportionkeepsunchangedaftermendinganditsmanufactureisconvenient.Itissuitableforstampingtheworkpieceswithcomplexshapeorhightolerancedemand.Butthewasteortheworkpieceinsuchcircumstancesispronetobeaccumulatedinsidetheholeofthecuttingedge,soincreasingtheexpandingforce,theejectingforceandthewearingofholewall.Theworncuttingedgeformstheshapeofinversecone,whichmayinducetheworkpiecejumpingfromtheopening-mouthoftheholetothesurfaceofthedie,andcausedifficultyinoperation.TheFig.1-14(a)typecuttingedgeofdieissuitableforthenon-circularworkpiece,andFig.1-14(b)typeissuitableforthecircularworkpiece,thediewhichtheworkpieceorwasteneedstobeejected,orthecompoundblankingdie.Fig.1-14(c)andFig.1-14(d)showthediewithconicalshapecuttingedge.Theworkpieceorwasteiseasytofalldownfromthediehole.Theworkpieceorwastewouldn’taccumulateeasilyinsidetheholeofthecuttingedge.Thefrictionandexpandingforceexertingontheholewallaresmall,thereforethewearingofthedieaswellasthemendingamountofthedieperoperationaresmall.Butthestrengthofcuttingedgeisabitlower.Thedimensionofcuttingedgeincreasesaftermending,butingeneralitsinfluenceontheworkpiecedimensionandthedielifeisweak.Thedieswithconicalshapecuttingedgesaresuitableforstampingthinworkpieceswithsimpleshapeandlowtolerancedemand.BlankingToolsDependingonthetypeofguidancefortheshearingelementswithrespecttooneanother,thetoolsaredividedintofree,plate-guided,andpillar-guidedblankingtooling.ThestructureofafreeblankingtoolissimilartotheoneshowninFig.1-15.Theshearingelementsofthetoolingarenotguidedwithrespecttooneanother;theguidanceofthetoolingisgenerallycontrolledbythepressramguides.Foragood-qualitypressanditsramguides,thetoolscanbeexpectedtobewellguidedunderload.Thefreeblankingtoolisthecheapesttypeofblankingtoolingbasedonthesimplicityofdesign.Itisthereforeusedforsmallerbatchsizes.Itisdifficulttoadjusttheclearanceallarounduniformlyatthetimeofinitialsetupofthetooling.Thiscanleadtolargerwear,especiallyforsmallthicknessass≤1mm,whentheclearancecanbeassmallas0.01mm.Inthecaseofaplate-guidedtoolsetup(Fig.1-16)theblankingpunchisguidedbytheguideplate.Insettingupthetoolingapositionalerrorcanthusbeavoided.TheeffectsofpoorguidanceofthepressguidesduetobearingclearancesandtheangulardeflectionofC-framepressesarereducedbyguidingthepunch.Anotheradvantageofpunchguidanceistheresistanceoflongpunchestobuckling.Theguideplateisalsousedasastripper.Theuseofablankingelementasaguidingelementmayposesomedisadvantages.Ifpropermeasuresarenottaken,thematerialpar