機械制造專業(yè)本科畢業(yè)設(shè)計外文翻譯

英文原文名FormingandDieDesign中文譯名成形工藝及模具設(shè)計英文原文版出處：《模具設(shè)計與制造專業(yè)英語》劉建雄王家惠廖丕博主編北京大學(xué)出版社2006年3月第1版譯文：金屬加工是工程科學(xué)的一個分支,它的制造金屬部件和結(jié)構(gòu)通過塑性成形過程加工、焊接和鑄造來完成。這局部著重于在金屬沖壓成形工藝及其模具設(shè)計加工。沖壓主要用于薄板成形,它不僅可以用在金屬成形,而且也可以用在非金屬形成。在沖壓成型,模具的作用下,內(nèi)力變形發(fā)生在板上。當(dāng)內(nèi)力到達一定程度時，相應(yīng)的塑性變形在空白區(qū)域發(fā)生。因此一定形狀的變形局部，是生產(chǎn)規(guī)模的特性。沖壓是通過沖模在壓力機上對金屬板料施加壓力使其產(chǎn)生塑性別離或變形從而得到滿足使用要求的加工方法，具有較高的生產(chǎn)效率。由于其操作簡單易于實現(xiàn)沖壓機械化和自動化。生產(chǎn)沖壓件的模具可以用來生產(chǎn)復(fù)雜的局部，所以可以用于其他加工方法難以加工的工件。沖壓件在使用中一般無需進一步加工。通常沖壓過程中不需加熱。因此，它不僅節(jié)約了材料，也節(jié)約了能量。此外，沖壓件具有重量輕、剛度大的特點。生產(chǎn)中為滿足沖壓零件形狀、尺寸、精度、批量、原材料性能等方面的要求，采用多種多樣的沖壓加工方法。概括起來沖壓加工可以分為別離工序與成形工序兩大類。別離工序是在沖壓過程中使沖壓件與板料沿一定的輪廓線相互別離的工序。對別離的橫截面的外表質(zhì)量必須滿足一定的要求。成型工序包括彎曲、拉深、翻邊、脹形、縮口、擠壓、擴口等，是毛坯在不被破壞的條件下產(chǎn)生塑性變形，形成所要求的形狀和尺寸精度的制件。沖壓工藝廣泛應(yīng)用在表1-1列出。表1-1的沖壓工藝分類及其特征1.2落料沖孔模沖裁沖裁是利用模具使板料的一局部另一局部沿一定的輪廓形狀別離的沖壓方法，包括落料、沖孔、切斷、修邊、切舌、剖切等工序，其中落料和沖孔是最根本的沖裁工序。落料和沖孔是金屬片沿一封閉輪廓處別離的過程。經(jīng)落料和沖孔板分為兩局部。沿封閉輪廓處別離，且別離的目的是為了獲得封閉輪廓形狀以外內(nèi)的局部〔即落下來的是工件〕那么為落料，如果是為了得到封閉輪廓形狀以外的局部〔即落下的是廢料，帶孔的是工件〕那么為沖孔。落料和沖孔的模具結(jié)構(gòu)是相同的，通常落料和沖孔的變形過程也是相同的。通過沖裁工藝，可以生產(chǎn)成品與半成品的變形過程。在圖1-1墊環(huán)顯示的情況下，得到的工件是Φ22毫米的圓叫落料，它的沖裁變形過程在中。沖裁變形過程沖裁時把板料固定在凹模上，凸模向下移動與板料接觸并開始沖裁。由于凸、凹模之間存在間隙，凸模對凹模和板料的力主要集中在凸模的邊緣。沖裁變形過程顯示在圖2中。如果模具間隙適宜，在凸模和凹模的作用下，變形過程經(jīng)歷三個階段，即，彈性變形，塑性變形和斷裂別離階段1.彈性變形階段在凸模壓力下，材料首先產(chǎn)生彈性壓縮，產(chǎn)生拉伸和彎曲變形，在這一階段，內(nèi)部應(yīng)力不超過彈性極限而不發(fā)生塑性變形，卸載壓力時變形恢復(fù)。2.塑性變形階段凸模繼續(xù)下壓，當(dāng)材料內(nèi)的應(yīng)力滿足屈服準那么時便開始進入塑性變形階段，在凸模和凹模的壓力下，對胚料的外表進行壓縮，由于凸模、凹模之間的間隙，使板料受到彎矩的的作用，產(chǎn)生彎曲變形，使凹模上的板料翹曲，兩者的過渡處〔凸凹模刃口處〕形成圓角。當(dāng)凸模擠入板料的深度增大，材料的塑性變形程度增大，變形區(qū)材料硬化加劇。當(dāng)刃口附近的材料由于拉應(yīng)力作用出現(xiàn)裂紋時，沖裁變形抗力到達最大值，塑性變形結(jié)束。3.斷裂別離階段凸模的繼續(xù)下壓，頂部和底部的裂縫逐漸延伸到金屬板的內(nèi)層，當(dāng)上下裂紋重合時，板料便被剪斷別離，完成沖裁。在沖裁過程中的斷裂帶的力量平衡圖1-3所示；F1、F2是凸、凹模對板料的垂直作用力，F(xiàn)3、F4是凸凹模對板料的側(cè)壓力；。μF1、μF2是凸凹模斷面與板料間的摩擦力，μF3、μF4μ是凸凹模側(cè)面與板料間的摩擦力；F1和F2的μ方向與凸模和凹模之間的間隙有關(guān)。沖裁力的分析說明，F(xiàn)3和F4側(cè)向壓力必須小于垂直壓力F1和F2；而裂紋擴展更容易發(fā)生在壓力小的區(qū)域。因此，沖裁時初始裂紋發(fā)生在凹模的側(cè)面。裂紋萌生和開展通過電子顯微鏡掃描說明，當(dāng)凸模向下擠壓的深度進入板料到達20%時，裂紋發(fā)生在凸模和凹模刃側(cè)外表，然后在頂部和底部的裂紋迅速擴展，當(dāng)兩個裂紋重合，毛坯剪切和斷裂過程結(jié)束。沖裁件質(zhì)量沖裁件的質(zhì)量主要是指割斷面狀況、尺寸精度和形狀誤差。工件的斷面質(zhì)量是決定沖裁工藝是否成功一個重要因素。如圖，沖裁件斷面可分為四個區(qū)域：蹋角帶、光亮帶、斷裂帶和毛刺。由于凸凹模刃口對板料進行塑性剪切而形成光亮帶，由于同時受到模具側(cè)面的擠壓力該區(qū)域不僅光亮且與板平面垂直，是斷面上質(zhì)量最好的區(qū)域，當(dāng)間隙適宜時，光亮帶約占板料厚度的1/2~1/3。斷裂帶形成于沖裁變形的斷裂階段，是裂紋向板內(nèi)部擴散的結(jié)果，是沖裁斷面上質(zhì)量最差的局部，不僅粗糙且?guī)в行倍?。蹋角帶是由于刃口附近的材料產(chǎn)生拉伸彎曲的結(jié)果，材料塑性越好，蹋角帶約大。毛刺形成于斷裂別離階段，形成的毛刺是細長的且附在工件上。影響斷面質(zhì)量的因素很多，四個區(qū)域的比例〔蹋角帶、光亮帶、斷裂帶和毛刺〕隨沖裁條件的變化而變化，如工件材料、沖床、模具和設(shè)備等。圖1-5顯示影響沖裁件斷面質(zhì)量的主要因素，圖1-6顯示影響沖裁件的尺寸精度的因素。研究分析說明，凸模和凹模之間的間隙是影響外表質(zhì)量和沖裁工件尺寸精度的重要因素，提高沖裁工件的外表質(zhì)量，是研究間隙對機制的影響具有重要的意義，從而找到計算凸模和凹模之間間隙的最正確的方法。沖裁?？傮w結(jié)構(gòu)設(shè)計1.沖裁模典型結(jié)構(gòu)〔1〕單工序模單工序模也叫簡單模，是指壓力機的一次行程只完成一道沖壓工序的模具。其結(jié)構(gòu)簡單〔見圖1-7中所〕，所以它可以容易地制造，它是適用于小批量生產(chǎn)。〔2〕級進模壓力機在一次行程下在不同工位完成多道工序的模具叫級進模，如圖1-8所示。條料送進時，定位銷2在沖孔之前定位，沖孔凸模4向下移動完成沖孔，產(chǎn)生工件8。當(dāng)沖孔凸模返回時，凸模4上的板料通過卸料板6卸下廢料7，胚料前進一個步距，然后開始第二個落料，重復(fù)以上步驟，板料的進距是通過定位銷來控制的。〔3〕復(fù)合模復(fù)合模是只有一個工位，并在壓力機的一次行程過程中完成兩道或兩道以上的沖壓工序的模具稱為復(fù)合模，如圖1-9所示。該復(fù)合模的主要特點是有一個凸凹模。凸模1的外圓沖裁凸模切邊，而內(nèi)孔是拉深模。凸模1跟滑塊向下移動，沖裁過程是通過沖壓模1和沖裁模4來完成的，沖裁工件的拉深凸模2推開工件，然后拉深模向下移動進行拉深。推桿5和卸料板3卸下拉深件9時，滑塊返回。復(fù)合模適用于大批量生產(chǎn)和高精度的沖裁。2.凸模和凹模凸模有三種國家標準的凸模，如圖1-10，在工作中應(yīng)確定凸模的尺寸。一種圓形凸模采用D=1.1~30.2毫米，B型為D=3~30.2毫米，快速變化的圓凸模為D=5~29毫米。固定在凸模固定板的圓形穿孔，孔底采用過渡配合H6為A和B類圓形凸模，基孔間隙配合H6為快速變化的圓形凸模。該凸模長度應(yīng)該由模具結(jié)構(gòu)確定。使用的固定卸料板和導(dǎo)料板〔見1-11〕，該沖頭長度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是導(dǎo)料板厚度；H是由凸修模量及凸模進入凹模的深度〔0.5~1毫米〕，一般去經(jīng)驗值〔10~20毫米〕包括模具閉合時凸模固定板與卸料板之間的平安距離。非標準凸模及其固定模式如圖1-12所示，同一模具凸模之間的距離很小，鉚接結(jié)構(gòu)可用于圓形凸模圖1-12〔a〕，一個結(jié)構(gòu)通常用于小沖孔如圖1-12〔b〕，快速更換式?jīng)_模一般用于易磨損的沖孔如圖1-12〔c〕，；對非圓凸模，如果它的大小是大了一點，它可以直接通過螺栓固定在模套上，而不是通過固定板、銷釘、螺栓、定位槽固定如圖1-12〔d〕；如果凸模的工作局部是非圓形的，圓形臺階結(jié)構(gòu)用于緊固局部，一個停止計應(yīng)加如圖1-12〔e〕。對于小的沖孔，也可以由低熔點合金固定在凸模固定板，無機環(huán)氧樹脂膠粘劑，如圖1-13所示?！?〕凹模沖裁模的結(jié)構(gòu)形式如圖1-14。圖1-14〔a〕和圖1-14〔b〕為直壁切邊模具。切削刃的強度很高，其工作局部的尺寸保持不變后修補和制造方便。它適用于沖壓工件形狀復(fù)雜或高公差要求的工件，但在這種情況下，工件廢料易積累在切割邊緣的孔內(nèi)，因此增加材料的擴展性和反沖力使孔壁穿孔。切削刃的磨損形式呈倒錐形狀，這可能會引起工件從孔開口跳到模具外表，造成操作困難。該圖1-14〔a〕模型切削刃是適用于非圓工件，且圖1-14〔b〕模型適用于圓形工件，使工件或廢料需要被噴出的模具，或復(fù)合沖裁模。圖1-14〔c〕和圖1-14〔d〕為錐形切削刃模具，工件或廢料容易落下。從?？?，工件或廢料不會積累在切割邊緣的孔內(nèi)。摩擦和擴大的孔壁上施加力小，因此穿模以及模具修補操作量小。但是切削刃的強度低一點，切削刃的修補后的尺寸增加，但一般工件尺寸對模具壽命的影響小。用錐形切削刃模具適用于沖壓形狀簡單的薄板工件和較低的公差要求的工件。沖裁工具根據(jù)沖裁原理相對于另一個導(dǎo)向型的工具，分為導(dǎo)料板、導(dǎo)料銷、側(cè)壓裝置。一個自由的沖裁工具的結(jié)構(gòu)類似于圖1-15中的顯示。模具的剪沖裁元件不會遵循各自的引導(dǎo)；對模具的導(dǎo)向一般是由壓力機滑塊引導(dǎo)控制。一個質(zhì)量好的沖壓件和導(dǎo)向結(jié)構(gòu)可以在引導(dǎo)下負載。沖裁工具在低本錢的根底上，設(shè)計簡單沖裁模具。因此適合用于小批量的生產(chǎn)。這很難在模具初始設(shè)置時調(diào)整周圍均勻的間隙，這可能會導(dǎo)致較大的磨損，特別是在小的厚度≤1毫米的板，間隙可以為0.01毫米。在一個引導(dǎo)工具設(shè)置的情況下〔圖1-16〕落料沖模由導(dǎo)料板引導(dǎo)。建立加工位置誤差可以防止。沖壓的微弱導(dǎo)向效果由于軸承間隙和C型壓力機角偏轉(zhuǎn)通過引導(dǎo)沖減。對凸模導(dǎo)向的另一個優(yōu)勢是長臂彎曲阻力。導(dǎo)向板也被用作一個卸料板。一個沖裁單元作為一個導(dǎo)向性的原理可能會帶來一些缺點。如果不采取適當(dāng)措施，材料顆粒粘?；蛲鼓?dǎo)致更快的磨損。同時對大型復(fù)雜模具精確制導(dǎo)孔加工困難，本錢更高。在案件的支柱引導(dǎo)沖裁模具〔圖1-17〕的導(dǎo)向作用和剪切彼此分開。支柱引導(dǎo)使這個工具準確，與其他原理的減少刀具磨損相應(yīng)的設(shè)計。不需要考慮軸承間隙誤差，在設(shè)置支柱引導(dǎo)的高精度模具，設(shè)置工具簡單、耗時少。支柱引導(dǎo)工具，如引導(dǎo)板的模具，可以有助于軸承負荷間隙和沖壓的角偏轉(zhuǎn)減少缺陷。根本支柱引導(dǎo)被視為工具來幫助建立和制造精確的工具。通常用支柱引導(dǎo)采取強側(cè)推力引起的非中心加載的工具和傾斜運動的G型機不允許位移過大。因此，支柱引導(dǎo)不是不準確的按下引導(dǎo)替代和較小的剛性壓力機。他們有不同的導(dǎo)柱，球軸承導(dǎo)軌負載下非常準確，他們之間會有小的摩擦，因此用快速開關(guān)的情況下，充分的潤滑機器。導(dǎo)柱導(dǎo)向工具也可以配備為材料的活動導(dǎo)向板。導(dǎo)向板安裝在立柱上，模具體一般是在工具上的彈簧支撐。該設(shè)計一般用于沖裁薄板沖裁片保證平整度。凸?？梢龑?dǎo)他直到它接觸板料。這就要求在板的導(dǎo)向孔非常精確的制造有雙導(dǎo)向，即在導(dǎo)柱導(dǎo)向工具和在導(dǎo)向板的凸模間導(dǎo)向。雙向?qū)е话闶侵圃毂惧X比擬高。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