材控專業(yè)英語(yǔ)4.Plastic-forming process and dies

Chapter4PlasticFormingProcessandDiesChapter4PlasticFormingProcessandDies4.1ForgingWordsandterms:Die模具，凹模Seasoned適用的Unparalleled空前的，無(wú)比的Conveyance運(yùn)輸工具GrossNationalProduct國(guó)民生產(chǎn)總值Difficult-to-machinealloy難切削合金Forging鍛造，鍛件

forgeman

鍛工Augment增長(zhǎng)，發(fā)展

cryogenic低溫的Nationaldefence

國(guó)防4.1ForgingThissectionisabriefintroductiontotheforgingindustryanditsproductsintermsoftheirimportantroleinourwayoflife,

highlightingtheirtechnologicalandeconomicsignificance.由于鍛造工業(yè)及鍛件在人們生活方式中起著很重要的作用，本節(jié)簡(jiǎn)單介紹鍛造工業(yè)及鍛件，并突出其技術(shù)（意義）和經(jīng)

濟(jì)意義。Thissectionisabriefintroduction，主句

4.1ForgingInearlierdaysforgingwastheprocessofshapingmetalbyheatingandhammering.過(guò)去，鍛造是一種利用加熱和錘擊使金屬成形的工藝。Today,metalisnotalwaysheatedforforgingandtheworkmaybeperformedbyseveraltypesofheavymachineswhichapplyimpactorsqueezepressurewithswiftprecision.現(xiàn)在，金屬不必通過(guò)加熱來(lái)鍛造，可以采用不同類型的重型機(jī)械來(lái)完成，這些機(jī)械具有沖擊力和擠壓力以及高精準(zhǔn)度。4.1ForgingIntoday’sforgingindustrytheskillandseasonedjudgmentoftheforgemanisenhancedbythemachinesofmoderntechnologytoproducemetalpartsofunparalleledstrengthandutility.在如今的鍛造工業(yè)中，現(xiàn)代機(jī)械技術(shù)提高了鍛工的技術(shù)以及豐富的經(jīng)驗(yàn)，使其能夠制造高強(qiáng)度和廣泛應(yīng)用的金屬工件。Theartofforgingisbeingaugmentbythescienceofforgingatanincreasinglyrapidrate.Thus,asservicerequirementsformechanicalpartshavebecomemoresevere,forginghasbecomemorethanthemereshapingofmetal.鍛造工藝隨著鍛造學(xué)科的發(fā)展，取得了長(zhǎng)足的進(jìn)步。這樣，隨著對(duì)機(jī)械零件應(yīng)用的需要日益增加，鍛造不僅僅用來(lái)使金屬成形。4.1ForgingForgingpermitsthestructureofmetalstoberefinedandcontrolledtoprovideimprovedmechanicalproperties.鍛造能細(xì)化并控制金屬組織，從而提高力學(xué)性能。Also,forgingproducesacontinuous“grainflow”inthemetalwhichcanbeorientedtofollowtheshapeofthepartandresultinmaximumstrengthefficiencyofthematerial.而且，鍛造在金屬中產(chǎn)生了連續(xù)的“晶粒流動(dòng)”，使晶粒能夠沿著零件形狀取向，從而使材料達(dá)到最大的強(qiáng)度效能。4.1ForgingSincevirtuallyallmetalscanbeforged--fromalumimumtozirconium—extensivecombinationsofmechanicalandphysicalpropertiesareavailabletomeetdemandingspaceageapplication.事實(shí)上，幾乎所有金屬都可以被鍛造--從鋁到鋯，可以通過(guò)機(jī)械性能和物理性能的良好結(jié)合，來(lái)滿足太空時(shí)代的應(yīng)用需求。4.1Forging4.1ForgingTechnically,forgingmaybedefinedastheprocessofgivingmetalincreasedutilitybyshapingit,refiningit,andimprovingitsmechanicalpropertiesthroughcontrolledplasticdeformationunderimpactorpressure.從技術(shù)上說(shuō)，鍛造可定義為在沖擊力或者壓力作用下通過(guò)控制塑性變形使金屬成形、細(xì)化及改善金屬機(jī)械性能來(lái)擴(kuò)大應(yīng)用范圍的工藝。4.1ForgingButthetruemeaningofforgingcanbemoreclearlyrecognizedbyconsideringthevarietyofwaysitservesmankindandtheimportantcharacteristicsforgedpartsofferthosewhodesign,purchaseandusethem.但是，鍛造的真正意義被意識(shí)到是通過(guò)它服務(wù)于人類的多樣化以及設(shè)計(jì)、購(gòu)買和應(yīng)用他們的客戶賦予鍛件的重要特性。4.1ForgingForgingarecommonlyfoundinmachinesandconveyancesatcriticalpointsofshockorstress-particularlywherereliabilityandhumansafetyareaffected,andyetthegreatvarietyofshapes,sizesandpropertiesavailableinforgingshasextendedthelistofcurrentapplicationsandpotentialfutureusesfarbeyondthispoint.通常，鍛件用于機(jī)械或交通運(yùn)輸工具的承受振動(dòng)或應(yīng)力的關(guān)鍵部位，特別是關(guān)系到可靠性和人身安全，并且，形狀、尺寸和性能的變化大大擴(kuò)大了鍛件的應(yīng)用范圍，其未來(lái)應(yīng)用遠(yuǎn)不止于此。4.1ForgingFromthestandpointofsize,forexample,forgingsmayrangefromtinycashregisterpartsweightingfractionsofanouncetomassivestructuralcomponentsweightingseveraltons.以尺寸為例，鍛件的尺寸范圍從重量不到一盎司的微型收銀機(jī)零件到數(shù)噸的大型結(jié)構(gòu)件。Likewise,forgingsareavailableinshapescoveringvirtuallyeverybasicconfigurationusefultoman.同樣，鍛件可以得到各種形狀，涵蓋了對(duì)人類有用的所有基本外形。Fromthestandpointof，從…角度來(lái)看

4.1ForgingTheyserveinoperatingtemperaturerangingfromcryogeniclevelstoover3000°Fandinenvironmentascorrosiveasnaturecandevise.鍛件的服役溫度從低溫到高達(dá)3000華氏度，可在類似自然界腐蝕環(huán)境中使用。Forgingareeconomicallycompetitivewithothertypesofpartsproducedincorrespondingmaterials.與同種材料的其他成形方法相比，鍛件在經(jīng)濟(jì)上具有競(jìng)爭(zhēng)力。4.1ForgingWhilethecommercialforgingindustryisnothugeinrelationtotheGrossNationalProduce,itisagiantinitscontributiontoourstandardoflivingandournationaldefence.鍛造工業(yè)在國(guó)民生產(chǎn)總值中所占比例并不大，但它在日常生活和國(guó)防中的作用巨大。Theoperatingcapabilitiesofmosttoday′smachinesandconveyanceslargelydependonthepropertiesachievableinforgedcomponents.當(dāng)大多數(shù)機(jī)械和交通運(yùn)輸工具的操作性能主要依靠鍛件的性能。4.1ForgingWithoutforgingandtheperformancecharacteristicstheyprovide,autos,airplanes,trucks,farmimplements,earthmovingmachines,missiles,industrialenginesandmachines,andtheimplementsofnationaldefense,asweknowthem,wouldnotbefeasible.沒(méi)有鍛件及其良好的性能，汽車，飛機(jī)，卡車，農(nóng)具，土方機(jī)械，導(dǎo)彈，工業(yè)引擎和發(fā)動(dòng)機(jī)，國(guó)防裝備都不可行。4.1ForgingModernmanufacturersarelookingahead-anticipatingthefutureneedsofindustryanddevelopingproductsandservicestomeetthem.現(xiàn)代制造商展望未來(lái)-預(yù)測(cè)工業(yè)的需求，并開(kāi)發(fā)產(chǎn)品和服務(wù)以滿足需求。Newmarketsarebeingidentified;newtechnologiesexplored;newmethodandprocessesrefined.新市場(chǎng)正在確立，新技術(shù)正在開(kāi)發(fā)，新方法和新工藝正在改進(jìn)。4.1ForgingAsefficientuseofmaterialbecomesmorenecessary,theabilityofforgingtoprovidestrengthwithminimumweightbecomesmoreattractive.材料的有效利用越來(lái)越重要，鍛造能夠以最低的重量達(dá)到所需的強(qiáng)度，因而更具吸引力。。Asmoreuseismadeofcostly,difficult-to-machinealloys,therelativeprecisionanddimensionaluniformityofforgedpartsbecomemoredesirable.Theproductsoftheforgingprocess-asoldasantiquity-arenewastomorrow.由于更多地使用了昂貴的難切削合金，鍛件的精密度和尺寸均勻性更加滿足需要。古老的鍛造工藝正日新月異。4.1.1Closed-DieForgingWordsandterms:Close-dieforging模鍛；opendieforging自由鍛；

dropstamping錘上模鍛；bottomdie下模；tup錘頭as-forged鍛造的；near-solvus接近固相線；residualstrain殘留應(yīng)變；insulation絕緣，隔熱；kineticenergyinput動(dòng)能輸入；discriminating有區(qū)別的；glasscoating玻璃敷層，vaporcushioning蒸汽墊4.1.1Closed-DieForgingTheproductionofclosed-dieforginginthetitaniumandnickel-basesuperalloys,whicharespecifiedforthemostexactingaerospaceapplications,isacomplexsequenceofprocesses.鈦合金和鎳基被指定為最準(zhǔn)確的太空應(yīng)用件，它們的模鍛是一系列復(fù)雜的工藝過(guò)程。Anessentialrequirementiscloseco-operationbetweenthemanufacturerofthebilletmaterialsandthedieforgerresponsibleforshapingthematerialtothegeometry,quality,andengineeringpropertyrequirementsoftheultimatecustomer.模鍛的基本要求是將坯料制造和模具成形緊密配合，使材料達(dá)到最終客戶要求的幾何形狀、質(zhì)量和工程性能。4.1.1Closed-DieForgingInforgingbothsuperalloysandtitaniumalloys,strictdisciplinesmustbefollowedtoobtainthedegreeoftemperaturecontrolandthedeformationrateneededtoproduceapredictableas-forgedstructureofthetypewhichwillsatisfactorilyrespondtothenear-solvustemperatureemployedforthefinebalancingofpropertiescalledforbycurrentspecifications.在鍛造超合金和鈦合金時(shí)，需要遵循嚴(yán)格的規(guī)范，進(jìn)行溫度和成形速率控制，以獲得可預(yù)測(cè)的鍛后結(jié)構(gòu)，這種結(jié)構(gòu)更好地對(duì)應(yīng)固相線溫度，可用于很好地復(fù)合現(xiàn)行技術(shù)規(guī)格的性能。4.1.1Closed-DieForgingThemainfactorsneedingcarefulcontrolinachievinganas-forgedstructurewhichisbothpredictableandreproducibleintermsofresidualstrain/grainstructuresare:dieperformgeometry;diepreheatingtemperature;lubrication/insulation;kineticenergyinput;continualmonitoringofworkpiecesurfacetemperature.依據(jù)殘余應(yīng)變/晶粒結(jié)構(gòu)可以預(yù)測(cè)和再生鍛后結(jié)構(gòu)，其中需要關(guān)注和控制的主要因素是：模具的幾何形狀、模具的預(yù)熱溫度、潤(rùn)滑/隔熱、動(dòng)能輸入以及工件表面溫度的持續(xù)監(jiān)控。Thediesarepreheatedtothelimitimposedbythestrengthofdiematerial.模具預(yù)熱的極限受模具材料的強(qiáng)度影響。Lubrication/insulationneedsdiscriminationuseiftheworkpieceistobesuitablydeformedandapplicationvariesfrom100%coverage,throughpartialcoverage,tonolubrication.Severalglassesofdifferentmeltingpointsandviscositieshavebeeninvestigatedandareusedforbothsuperalloyandtitaniumforgings.

為了工件適用于成形，潤(rùn)滑/隔熱需要區(qū)別使用，可以全部潤(rùn)滑，部分潤(rùn)滑或者不潤(rùn)滑。幾種不同熔點(diǎn)和黏度的玻璃被用于超合金和鈦合金鍛件4.1.1Closed-DieForging4.1.1Closed-DieForgingIndropstamping,controlofthekineticenergyinputisachievedbytheheighttowhichthetupisraised,thusquiteaccuratelydeterminingtheenergyofeachblow.在錘上模鍛中，通過(guò)錘子升高的高度控制動(dòng)能輸入，這樣可以準(zhǔn)確控制每一錘的能量。Thefrequencyoftheblowsneedscarefulcontroltoachieveabalancewhichwillholdthetemperatureoftheforgingwithinanarrowband.錘擊的頻率需要仔細(xì)控制，從而達(dá)到平衡，控制鍛造溫度在一個(gè)窄的區(qū)間。Todothisinarepeatablemannerinvolvescloseco-operationbetweenthehammeroperativesandthetechnicalstaffwhosupervisetheoperationandconstantlymonitorthesurfacetemperatureoftheworkpiecetoeffectthebalancebetweenkineticheating,naturalcooling,anddiechilling.以重復(fù)的方式進(jìn)行，需要錘子操作者和技工的緊密配合，技工的監(jiān)控操作，并繼續(xù)檢測(cè)工件的表面溫度，來(lái)影響動(dòng)態(tài)加熱、空冷和模具急冷之間的平衡。4.1.1Closed-DieForging4.1.1Closed-DieForgingThelatterisminimizedbyglasscoatingandbyvaporcushioninginthebottomdieinwhichtheforgingsometimeslevitatesandrotates.后者（模具冷卻）可用玻璃涂層和下模的蒸汽墊來(lái)最小化，在下模中鍛件有時(shí)會(huì)浮起或者旋轉(zhuǎn)。Theadvantanges

intermsofeaseandspeedofhandlingoftheforginginafixedbottomdieareevident,sincedelaysofmorethanafewsecondsduetorelocatingforgingswhichhavejumpedoutofregisterwiththediescanmarkedlyaffecttheendresultsbecauseoftheheatlostduringthedelay鍛造在固定下模中處理的方便和速度，其優(yōu)點(diǎn)很明顯。由于再定位鍛件退后數(shù)秒，鍛件會(huì)隨著模具跳動(dòng)離開(kāi)原位置。時(shí)間推遲而產(chǎn)生熱量損失而顯著影響成形效果。4.1.1Closed-DieForgingByusingthetechniques

described

thedegreeofthesurfacechillingoftheforgings

duetodiecontact,withitsconsequenteffectonsurfacecrackingpotentialandlimitationofmetalflowneardiecontactsurfaces,canbeminimized,thusenablinginmanycasesamoreeconomicuseofmaterialthanispossiblewithforgingprocessesinwhichtheforginganddieareincontinuouscontact.采用上述技術(shù)，鍛件表面與模具接觸而冷卻的程度可以最小化。這種冷卻程度隨后影響表面潛在開(kāi)裂和限制接觸模具的區(qū)域

金屬的流動(dòng)。許多情況下，在鍛造工藝條件下，使鍛件和模

具持續(xù)接觸使用材料更加經(jīng)濟(jì)。4.1.2PressForging-壓鍛Wordsandterms:Press壓力機(jī)，壓力；closedimpressiondie閉式壓鍛模；Draft阻力，牽引力；dropforging落錘鍛；sizingoperation精鍛工藝；hydraulicpress液壓機(jī)；finalforging終鍛；pyrometer高溫計(jì)4.1.2PressForgingPressforgingemploysaslowsqueezingactionindeformingtheplasticmetal,ascontrastedwiththerapid-impactblowsofahammer.Thesqueezingactioniscarriedcompletelytothecenterofthepartbeingpressed,thoroughlyworkingtheentiresection.與采用錘擊的快速擊打相反，壓力鍛造采用緩慢的擠壓作用使金屬變形。擠壓作用完全施加在工件中心，徹底使之變形。Thesepressesaretheverticaltypeandmaybeeithermechanicallyorhydraulicallyoperated.Themechanicalpresses,whicharefasteroperatingandmostcommonlyused,rangeincapacityfrom500to10000tons.這種壓力由機(jī)械或液壓垂直施加，機(jī)械壓力被廣泛應(yīng)用，它可以快速施壓，其施壓范圍為50-10000噸。4.1.2PressForgingForsmallpressforgings,closedimpressiondiesareused,andonlyonestrokeoftheramisnormallyrequiredtoperformtheforgingoperation.小型壓鍛件可采用閉式壓鍛模，一次擠壓操作就可以完成鍛造過(guò)程。Themaximumpressureisbuildupattheendofthestrokewhichforcesthemetalintoshape.Diesmaybemountedasseparateunits,orallthecavitiesmaybeputintoasingleblock.壓力在擠壓動(dòng)作結(jié)束時(shí)候達(dá)到最大，以使材料成形。模具可以分為多個(gè)單元進(jìn)行固定，所有的凹模也可采用一個(gè)模塊。Forsmallforgingsindividualdieunitsaremoreconvenient.

Thereissomedifferenceinthedesignofdiesfordifferentmetals,copper-alloyforgingscanbemadewithlessdraftthansteel,consequently,morecomplicatedshapescanbeproduced.Thesealloysflowwellinthedieandarereadilyextruded.對(duì)于小型鍛件成形更方便。不同金屬模具設(shè)計(jì)不同，銅合金

比鋼的鍛壓阻力小，因此，可以鍛造成復(fù)雜的形狀。這些合

金在模具中流動(dòng)性好，可以順利擠出。4.1.2PressForging4.1.2PressForgingIntheforgingpressagreaterproportionofthetotalworkputintothemachineistransmittedtothemetalthaninadrophammerpress.Muchoftheimpactofthedrophammerisabsorbedbythemachineandfoundation.Pressreductionofthemetalisfaster,andthecostofoperationisconsequentlylower.在壓力鍛造中，傳遞到金屬上的壓力比落錘鍛的壓力要大得多。鍛錘的沖擊力大部分被機(jī)械和底座吸收。金屬的壓力減少越快，操作成本也相應(yīng)越低。Mostpressforgingsaresymmetricalinshape,havingsurfaceswhicharequitesmooth,andprovideaclosertolerancethanisobtainedbyadrophammer.大部分壓鍛件形狀比較勻稱，表面光滑，比錘鍛件有更好的公差等級(jí)。However,manypartsofirregularandcomplicatedshapescanbeforgedmoreeconomicallybydropforging.Forgingpressesareoftenusedforsizingoperationsonpartsmadebyotherforgingprocesses.但是，對(duì)于形狀不規(guī)則和復(fù)雜的工件來(lái)說(shuō)，采用錘鍛比較經(jīng)濟(jì)。壓鍛常用于其他鍛壓后的精鍛工藝4.1.2PressForging4.1.2PressForgingIndropforging,apieceofmetal,roughlyorapproximatelyofthedesiredshape,isplacedbetweendiefaceshavingtheexactformofthefinishedpiece,andforcedtotakethisformbydrawingthediestogether.落錘鍛過(guò)程中，接近期望形狀的片狀金屬被置于模面之間，最終成形為尺寸精確的工件。Thismethodiswidelyusedforthemanufactureofpartsbothofsteelandbrass.Largeingotsarenowalmostalwaysforgedwithhydraulicpressesinsteadofwithsteamhammers,sincetheworkdonebyapressgoesdeeper.這種成形方法廣泛應(yīng)用于鋼和黃銅件的制造。大鑄錠目前幾乎全部采用液壓機(jī)取代汽錘進(jìn)行鍛造，這樣壓力更大。4.1.2PressForgingFurther,thepresscantakeacooleringotandcanworktocloserdimensions.Theforgingshouldbedoneataboutthesametemperatureasrolling;theprocessimprovesthephysicalpropertiesofthesteeljustasrollingdoes.以后，可以進(jìn)行冷鑄錠的成形并接近最終尺寸。鍛造應(yīng)在與軋制相同的溫度下進(jìn)行，與軋制一樣可以改善鋼的物理性能。Inthefinalforgingitisimportantnottohavethesteeltoohot,foranoverheatedsteelwillhavepoormechanicalpropertieswhencooled.終鍛階段，要注意鋼不能太熱，因?yàn)檫^(guò)熱鋼冷卻后力學(xué)性能變差。Inheatingforforgingthetemperatureisusuallyjudgedbytheeye,butwherelargenumbersofthesamepatternaremade,thepiecetobeforgedareheatedinfurnacesinwhichthetemperatureisindicatedbypyrometers,andoftenisautomaticallycontrolled.鍛件的加熱溫度通常用肉眼判斷，但制造大量相同方式的

鍛件時(shí)，通過(guò)爐子加熱，爐內(nèi)的溫度通過(guò)高溫溫度計(jì)測(cè)量，

并能實(shí)現(xiàn)自動(dòng)控制。4.1.2PressForgingWordsandterms:Rotarybending旋轉(zhuǎn)模彎曲；veebendingV型槽模彎曲；wipebending折彎彎曲；tonnage噸位；built-incam內(nèi)置凸輪；consistency一致性4.2RotaryBending

Pressworkingoperationshaveincreaseddramaticallyoverthelastfewyears,butlikemanyothermanufacturingoperations,theexistingtechnologyhassometimesfailedtokeeppacewiththechangingapplications.Oneareawherethisisespeciallytrueisdiebending.壓力加工在過(guò)去數(shù)年中顯著增長(zhǎng)，但是和許多其他制造方法一樣，現(xiàn)有的技術(shù)難以與變化的應(yīng)用保持同步。典型的例子就是彎曲模。4.2RotaryBendingSo,althoughthereisasubstantialincreaseintheapplicationsforbending,thetwomostcommonformsofbendingmethod—veebendingandwipebending—representtechnologiesthataresometimesquiteoutdatedfortoday”shighvolumeproductionrunsandprecisionrequirements.所以，盡管彎曲件的應(yīng)用大幅增加，兩種通用的主要彎曲方式—V型槽模彎曲和折彎彎曲有時(shí)明顯落后于現(xiàn)代大體積產(chǎn)品的大量生產(chǎn)和精密的要求。4.2RotaryBendingDiebendingoperationsoftenpresentthetooldesignerwithavarietyofproblemareas,especiallywhenhighvolumeproductionisafactor.模具彎曲通常出現(xiàn)一系列問(wèn)題，特別是大體積產(chǎn)品。4.2RotaryBendingFromproducingproperbendanglesandminimizingpartdistortiontoreducingtherequiredtonnageandkeepingthematerialinplaceduringthebend,theolderveebendingandwipebendingmethodscaneasilycreatemanyproblemsastheysolve.在彎曲過(guò)程中，從產(chǎn)生合適的彎曲角度和最小扭曲到減少需求的噸位和固定材料，舊的V型槽模彎曲和折彎彎曲很容易產(chǎn)生許多問(wèn)題。Butaneweralternative,rotarybending,mayjustbethesolutiontotheproblemscausedbytheotherbendingmethods.但一個(gè)新的替代，旋轉(zhuǎn)模彎曲可以解決其他彎曲方法產(chǎn)生的問(wèn)題。4.2RotaryBendingTherotarybendingprocess,developedandpatentedbyReadyTool,Inc.,Dayton,OH,isahighlyefficientmethodofproducingawiderangeofdifferentbends.旋轉(zhuǎn)模彎曲由ReadyTool公司發(fā)明并申請(qǐng)專利，它是一種可生產(chǎn)大范圍彎曲件的高效方法。Thisformofbendingdiecanmakepreciseandaccuratebendsinmaterialsrangingfrom0.008in.to0.500in.atbendingtonnagethatare50to80percentlessthanthoserequiredfortheotherbendingmethods.這種彎曲?？梢灾圃旄呔鹊膹澢趶澢鷩嵨幌?，彎曲精度為0.008-0.500英尺，比其他彎曲方法需要的噸位少50-80%。4.2RotaryBendingAsshowninFig4.1,transferringtheverticalmotionofthepressintoarotarymotionofthebender,permitsahighlyefficientandeffectivemethodofbendingmetal.Usingthisformofbuilt-incamactionalsoprovidesanuncommondegreeofbendingaccuracyandconsistency.如圖4.1所示，將壓力的垂直運(yùn)動(dòng)轉(zhuǎn)換為旋轉(zhuǎn)運(yùn)動(dòng)，是高效和具有影響的金屬?gòu)澢椒ā２捎脙?nèi)置凸輪也能提供不尋常的彎曲精度和一致性。4.2RotaryBending4.2RotaryBending圖4-1旋轉(zhuǎn)模彎曲過(guò)程不需再壓模Wheremanybendingoperationswerepreviouslyperformedinaseriesofstepstomaintaintherequiredaccuracy,rotarybendinggenerallypermitstheoperationstobeperformedinpressstroke.之前的彎曲工藝需要一系列工序保證精度，而旋轉(zhuǎn)彎曲通常一次施壓就能完成。4.2RotaryBendingRotarybendingwillnotcompletelyreplacetheneedforeitherveebendingorwipebendingforallapplications.Butinthosesituationswhererotarybendingisappropriate,thecostsavingsandoverallefficiencyofvirtuallyanybendingoperationcanbemarkedlyincreased.旋轉(zhuǎn)模彎曲也不能完全替代V型槽模彎曲或者折彎彎曲。但是那些旋轉(zhuǎn)模彎曲適合的情況下，在經(jīng)濟(jì)效益和實(shí)際效率比其他彎曲方法顯著提高。4.2RotaryBendingWordsandterms:Fineblanking精密沖裁；cutedge剪切刃shaving刨削；clearance間隙，公差中的公隙；blank落料件；producinghole沖孔；cuttingpunch沖裁凸模；burr毛刺；bolster墊板；ejector卸料器；orthodox傳統(tǒng)的；shearingzone剪切區(qū)4.3FineBlankingFineblankingisatechniqueusedforproductionofblanksperfectlyflatandwithacutedgewhichiscomparabletoamachinedfinish.Thisquickandeasyprocessisworthyofseriousthoughtwhenthenumberofpartsjustifiesthecostofablankingtoolespeciallywhenconsiderationisgiventothefactthatoperationssuchasshavingareeliminated.精密沖裁是一種采用剪切刃精確沖裁板料產(chǎn)品的技術(shù)，它的剪切刃可與機(jī)械精加工相媲美。這種既快捷又方便的加工方法值得認(rèn)真考慮，特別是考慮到可省掉像刨削這樣的操作，零件的數(shù)目也證實(shí)了沖裁工具的成本下降了。4.3FineBlankingTwomethodsoffineblankingarepracticedaccordingtothetypeofworkundertakenasfollows:(1)Thepunchhasaroundedgeandasmallclearanceandthisisbestusedforblanks,butappearstogivelesssatisfactoryresultswhenusedforproducingholes.(2)ThismethodusesacuttingpunchwhichissurroundedbyaV-shapedgripperwhichmakesaV-grooveroundtheprofileandthusclampstheblanksecurelybeforeanonroundpunchcontactsthesurface.根據(jù)加工工件的類型可分為以下兩種精密沖裁方法：(1)凸模有圓角邊和小的間隙，這最適合于落料件，但是對(duì)于沖孔似乎沒(méi)有較滿意的結(jié)果(2)該方法使用一個(gè)外廓四周形成V槽的V型夾板包圍的的沖裁凸模，在一個(gè)非圓形的凸模接觸表面之前，夾具緊緊夾住落料件。4.3FineBlankingInmethod1theradiusontheedgeofadieisselectedaccordingtothetypehardnessandthicknessofaparticularmaterialcoupledalsototheshapeofaprofileonthecomponent.在方法1中，沖模的圓角半徑由特定材料的硬度和厚度以及輪廓外形決定。Howeversomeimportanceisattachedtothisradius,otherwisealargeincreasecancausedistortionandcreateaburrontheundersideoftheblank.Thustheminimumradiusthatwillimpartagoodresultonacomponentisanessentialfeatureandthisradiuscanvaryfrom0.3to2mmaccordingtoconditions.半徑很重要，半徑過(guò)大會(huì)導(dǎo)致變形和在落料件的下側(cè)出現(xiàn)毛刺。因此，最小半徑是一個(gè)重要特性，有利于零件。根據(jù)不同條件，半徑可在0.3-2之間變化。4.3FineBlankingGenerallytheloadrequiredforfineblankingisnomorethan10%greaterthantheloadneededforconventionalblanking.通常精密沖裁所需的加載只比傳統(tǒng)沖裁大10%。Greaterradiusandthusburstingpressuresareexperiencedwiththisoperation,soattentiontobethedesignofthetoolisnecessaryandthisusuallymeanssinkingthediecompletelyintoabolsterofadequateproportions.精密沖裁可以加工大半徑和得到大的爆裂壓力，因此必須注意工具設(shè)計(jì)，這意味著讓沖模完全沉入的墊板必須有足夠的面積。4.3FineBlankingWell-supportedpunchesareessentialtoensurethatthedeflectioniseliminatedandthereisnoneedtostresstheconsequencesofafailuretogiveattentiontothispointinadesign.為了確保消除凸模偏轉(zhuǎn)，牢固凸模很重要，沒(méi)必要強(qiáng)調(diào)后續(xù)失誤而注意該點(diǎn)的設(shè)計(jì)。Sharpcuttingedgesareyetanotheritemthatmustreceivecontinuedthoughtandthereisapparentlyacasehereforpunchesmadefromhigh-carbonhighchromiumsteel.鋒利的剪切刃也值得注意，一個(gè)明顯的例子是由高鉻鋼制成的凸模。4.3FineBlankingThequestionofpunchanddieclearancesisavitalpointwiththisdesignoftoolandtheyarealwaysmuchcloserthanthoseusedforconventionalblankingtools.工具設(shè)計(jì)中一個(gè)至關(guān)重要的問(wèn)題（要點(diǎn)）是凸模和凹模間的間隙，它們比傳統(tǒng)沖裁工具中的間隙都要小些。Asageneralguideatotalclearanceof0.01to0.03mmwillgivegoodresultsandemphasisismadeofthepointthatthesearetotalclearancesandnoteachsideofaholeorblank.通常規(guī)定，總間隙在0.01-0.03mm之間為好，需要強(qiáng)調(diào)的是，這里說(shuō)的是總間隙而不是每一個(gè)孔或落料件的間隙。4.3FineBlankingStrippingforcestoremovetheblankfromthepuncharehigher,duetothesmallclearancesandtheloadneededtostripthematerialsestimatedasbeing10%higherthanfornormalblankingtools.由于間隙小，將落料件從凸模中脫離的脫模力較高，脫出材料所需的加載比普通沖裁工具的高出10%左右。4.3FineBlankingMethod2employstheV-shapedsurroundtoholdtheblankduringtheoperationandthisprojectionisforcedintothematerial.Fig4.2showsbrieflywhathappensasthepressdescends;theillustrationsindicatehowthepressureplateclampsthestrip,howblankingiscarriedoutandthefinalejectionofapartbythelowerejector.第二種方法采用V型凸邊圍繞落料件并夾緊，這樣凸邊壓進(jìn)材料中。如圖4.2所示，為壓力沖下時(shí)的情形，圖中顯示了壓力板如何夾緊帶鋼、如何實(shí)現(xiàn)沖裁以及最終零件如何由下級(jí)卸料器排出。4.3FineBlanking圖4-2帶V形夾板的精密沖裁過(guò)程

精密沖裁中，剪切時(shí)破壞應(yīng)力僅發(fā)生在凸凹刃口處，在剪切區(qū)材料只產(chǎn)生了變形。Anappreciationofthedifferencebetweenordinaryblankingandfineblankingisofinterest.Forexamplewhentheshearingprocesstakesplaceonanorthodoxblankingtool,thedeformationofamaterialoccursintheshearingzoneandthebreakingstressisattainedbeforethepunchhascompletelypenetratedthematerial.有必要認(rèn)識(shí)普通沖裁和精密沖裁的不同。例如，用傳統(tǒng)的沖裁工具剪切加工時(shí)，材料的變形發(fā)生在剪切區(qū)，破壞應(yīng)力發(fā)生在凸模完全穿透材料之前4.3FineBlankingWordsandterms:Convergingdie收口模；wiredrawing拔絲；opendieextrusion開(kāi)式模擠壓；hydrostaticextrusion靜液擠壓；confinedchamber閉式模腔；billet坯料；isotropic各向同性；logarithmicstrain對(duì)數(shù)應(yīng)變；workpiece工件；inertiaforce慣性力；adiabatic絕熱的4.4FlowThroughConicalConvergingDiesThestudyofmetalflowthroughconicalconvergingdiescoverssuchprocessesaswiredrawing,open-dieextrusion,hydrostaticextrusion,andextrusionthroughaconfinedchamber.通過(guò)圓錐收口模的金屬流動(dòng)研究包括諸如拉絲、開(kāi)式擠壓、靜液擠壓和通過(guò)閉式模腔的擠壓等工藝。4.4FlowThroughConicalConvergingDiesFig4.3representsabilletanddie.Thebilletismadeofahomogeneousisotropicmaterialofconstantstrength;considerationwillbegivenlatertovariablematerialproperties.圖4.3所示為一個(gè)鋼坯及模具。鋼坯由等強(qiáng)度的各向同性材料制成，不同的材料特性將在后面分析。Inform,thebilletisacylindricalrodofradiusR0;therodisreducedtoradiusRf

byforcingittopassthroughtheconicalconvergingdie.Thereductionismeasuredfromthecross-sectionalareaofthebilletattheentrancetothedie(A0)tothatattheexit(Af).形式上，鋼坯為半徑R0的圓柱形棒料，將該棒料壓入圓錐收口模具中，其半徑變?yōu)镽f

。半徑的縮小通過(guò)模具入口處(A0)到出口處(Af)的橫截面積測(cè)量。4.4FlowThroughConicalConvergingDies4.4FlowThroughConicalConvergingDiesThreevariablesinvolvedinthereductionprocessarenotedatonce:(1)Reduction,whichcanbemeasuredbytheradiusratior(%)=R0/Rforarelatedexpression,namely,thearearatio(R0/Rf)2,theareareductionratio(A0-Af)/A0=1-Af/A0=1-(R0/Rf)2,thepercentagereductioninarea,ortheeffectiveorlogarithmicstrain[Φeff=2ln(R0/Rf)].在縮徑過(guò)程中涉及的三個(gè)變量如下：（1）收縮量，可以用半徑比R0/Rf；或者相關(guān)的表達(dá)方式面積比(R0/Rf)2；面積的縮?。?A0-Af)/A0=1-Af/A0=1-(R0/Rf)2；面積百分比的縮小或者對(duì)數(shù)應(yīng)變[Φeff=2ln(R0/Rf)]來(lái)衡量。4.4FlowThroughConicalConvergingDies(2)Thesemiconeangleofthedie,α,i.e.,halfthedieangle.Inwiredrawingαisrelativelysmall,possibly6°to12°,open-dieextrusionmayemployα=60°;forextrusionthroughaclosedchamberthediemaybe“square”,withα=90°.（2）模具半錐角，是?？诮堑囊话?。在拉絲中的半錐角α相對(duì)較小，可能在6-12°；開(kāi)式擠壓可能采用α=60°；對(duì)于通過(guò)閉合模腔的擠壓來(lái)說(shuō)，模具可能是方形的，即α=90°4.4FlowThroughConicalConvergingDies(3)Frictionbetweenthedieandtherod.Wheneverthereisrelativemotionbetweentwosurfaces,thereisresistancetothismotion,andthisresistanceiscalledfriction.Themechanicsoffrictionarecomplex.（3）第三個(gè)變量為模具和坯料棒之間的摩擦。不論何時(shí)，這兩個(gè)表面都存在相對(duì)運(yùn)動(dòng)，這種阻力成稱為摩擦。摩擦機(jī)理很復(fù)雜。Althoughthefundamentalsofthephenomenonhavebeengivenmuchstudy,verylittlethatisknownwouldfacilitateformulationoftheexactfunctionalrelationshipbetweenfrictionandtheotherprocessvariables.盡管對(duì)于摩擦現(xiàn)象的基本原理已經(jīng)進(jìn)行了很多研究，但幾乎沒(méi)有摩擦和工藝變化量化的的精確關(guān)系。4.4FlowThroughConicalConvergingDiesThemostcommonsimplifyingassumptionsmadewithregardtothefrictionstressbetweentheworkpieceandthetoolarethefollowing:通常對(duì)于工件和工具之間的摩擦應(yīng)力關(guān)系采用如下簡(jiǎn)化假定：1)Coulombfriction.Itisassumedthattheshearstressτ

isproportionaltothepressurepbetweentheworkpieceandthedie.Thenτ

=μp，wheretheproportionalityfactorμiscalledtheCoulombcoefficientoffriction,assumedconstantforagivendie,workpiece,andlubricant.（1）庫(kù)倫摩擦。假定工件和模具間的剪切應(yīng)力和壓力成比正比。τ=μp，比例系數(shù)μ稱之為庫(kù)倫摩擦系數(shù)，對(duì)于給定的模具、工件和潤(rùn)滑劑假定為常數(shù)。4.4FlowThroughConicalConvergingDies2)Constantfriction.Itisassumedthattheshearstressisproportionaltothestrengthoftheworkpiecematerial.Then

τ

=mσ0/31/2,wheretheproportionalityfactormiscalledtheshearfactor,with0≤m≤1assumedconstantforagivendie,workpiece,andlubricant.（2）恒定摩擦。假定剪切應(yīng)力與工件材料強(qiáng)度成正比。此時(shí)，τ=mσ0/31/2，比例系數(shù)m為剪切因子，對(duì)于給定的模具、工件和潤(rùn)滑劑假定0≤m≤1。4.4FlowThroughConicalConvergingDies3)hydrodynamic-hydrostatic-,andthickfilmlubrication.Whenalubricantfilmseparatestheworkpiecefromcontactwiththedie,thenhydrodynamic-orhydrostatic-filmlubricantprevails,withitsspeciallawsofshearwithinthelubricantmedium.Sometimeshighviscositylubricantsadheretotheworkpiecetoperformthickfilmseparationoftheworkpiece

fromthetool.（3）流體動(dòng)力-流體靜力的及厚潤(rùn)滑膜層。當(dāng)潤(rùn)滑膜使工件和模具接觸分離，在潤(rùn)滑劑介質(zhì)的作用下存在專門的剪切定律，此時(shí)流體動(dòng)力的或流體靜力的潤(rùn)滑膜占據(jù)優(yōu)勢(shì)。有時(shí)，高粘度潤(rùn)滑劑黏結(jié)工件，形成厚膜將工件和工具分開(kāi)。4.4FlowThroughConicalConvergingDiesThesethreeprocessvariable—reduction,coneangle,andfriction-areindependentinthattheprocessplannermaychoosetheirvaluesseparatelywithinlimits.(theseverityoffriction,forinstance,iscontrolledbychoicesoflubricant,diematerialandfinish,speed,etc.)收縮量、錐角和摩擦這三個(gè)變量相互獨(dú)立，因?yàn)楣に囋O(shè)計(jì)者在限定范圍內(nèi)可能分別選擇其數(shù)值，（例如，摩擦的嚴(yán)重程度由潤(rùn)滑劑的選擇、模具材料和表面處理、速度等控制）。4.4FlowThroughConicalConvergingDiesTheyaretheprimaryfactorsaffectingtheprocess,andtheireffectsonthefirstdependentparameter,thedrawingorextrusionforce,willbeanalysedfirst.這些變量是影響工藝的主要因素，它們影響首要依賴的參數(shù)、拉拔或者擠壓力，首先分析。Otherindependentparametersplayaroleduringprocessing.Forexample,wewillfindthatthedrawingorextrusionforceislinearlyproportionaltotheflowstrengthofthematerial,butwheninertiaforcesareneglecteditisindependentofthespeed.其他獨(dú)立參數(shù)也發(fā)揮作用。例如，拉拔或擠壓力與材料強(qiáng)度呈線性比例關(guān)系，但當(dāng)忽略慣性力時(shí)，其與速度無(wú)關(guān)。4.4FlowThroughConicalConvergingDiesThepowerintheotherhandislinearlyproportionaltothespeed.Furthermore,wewillfirstconsiderisothermalprocessing,wheretemper