unit13夾具與固定裝置

ProfessionalEnglish（13）

北華大學機械學院王開寶Unit13JigsandFixture

鉆模與夾具

Introduction導言Ithasalreadybeenstatedthattheworkpiecemustbelocatedrelativetothecuttingtool,andbesecuredinthatposition.Aftertheworkpiecehasbeenmarkedout,itisstillnecessarytopositionitwithrespecttothemachinemovements,andtoclampitinthatpositionbeforemachiningisstarted.已經說明了工件必須相對于切削刀具定位并確保到位。工件劃線后，仍有必要將其相對于切削運動定位，并在機加工開始前把它裝夾到位。

Whenseveralidenticalworkpiecesaretobeproducedtheneedtomarkouteachpartiseliminatedbytheuseofjigsandfixtures,butifacastingorforgingisinvolved,atrialworkpieceismarkedout,toensurethattheworkpiececanbeproducedfromit,andtoensurethatribs,cores,etc.havenotbecomemisplaced.

當要加工若干同樣的工件時，使用鉆模和夾具可以不必在每個工件上劃線；但對鑄件或鍛件而言，還需取一試驗工件劃線以保證照此加工不會將加強肋、型芯等放錯位置。Jigsandfixturesarealikeinthattheybothincorporatedevicestoensurethattheworkpieceiscorrectlylocatedandclamped,buttheydifferinthatjigsincorporatemeansoftoolguidingduringtheactualcuttingoperation,andfixturesdonot.鉆模和夾具的相似點是它們都把保證工件正確定位和夾緊的裝置相結合，它們的不同在于鉆模在實際切削作業(yè)中還能與刀具導向方法相結合，而夾具則不能。Inpractice,theonlycuttingtoolsthatcanbeguidedwhileactuallycuttingaredrills,reamers,andsimilarcutters;andsojigsareassociatedwithdrillingoperations,andfixtureswithallotheroperations.Fixturesmayincorporatemeansofsettingthecuttingtoolsrelativetothelocationsystem.實際上，在真實切削中能被導向的切削刀具只有鉆頭、鉸刀和類似的刀具；因此鉆模用于鉆削作業(yè)，而夾具用于其余作業(yè)。夾具可以與切削刀具相對定位系統(tǒng)裝夾的方法結合在一起。Theadvantagesofjigsandfixturescanbesummarisedasfollows:1)Markingoutandothermeasuringandsettingoutmethodsareeliminated;鉆模和夾具的優(yōu)點可歸納如下：1)可以省去劃線和其它測量及放樣程序；2)Unskilledworkersmayproceedconfidentlyandquicklyinknowledgethattheworkpiececanbepositionedcorrectly,andthetoolsguidedorset;2)在知道工件能正確定位、刀具能恰當導向或裝夾的情況下，不熟練的工人也能自信而快速地操作；Boltholesoftenhave1.5mmoreven3.0mmclearanceforthebolt,andthereadermaydoubtthenecessityofmakingprecisionjigsforsuchwork.Itmustberememberedthatthejigs,oncemade,willbeusedonmanycomponents,andtheextracostofanaccuratelymadejigisspreadoveralargeoutput.螺栓孔常給螺栓留出1.5毫米或甚至3.0毫米的間隙，讀者可能會懷疑為這樣的工作制造精密鉆模的必要性。但要記住，這種鉆模一旦造好，可用于許多零部件，精確制造鉆模的額外成本可分攤在大量產品上。Furthermore,itissurprisinghowsmallerrorsaccumulateinamechanismduringitsassembly.Whenaclearanceisspecified,itisbettertoensureitsobservance,ratherthantoallowcarelessmarkingoutandmachiningtoencroachuponit．此外，這樣做在裝配機械裝置時其累積誤差之小也是令人驚訝的。在確定一個間隙時，最好能保證它的習慣要求，而不是隨便劃線和機加工使其超出正常的界限。1)Thelocationofworkpiece.Fig.13.1representsabodythatiscompletelyfreeinspace.Inthisconditionithassixdegreesoffreedom.ConsiderthesefreedomswithrespecttothethreemutuallyperpendicularaxesXX,YY,andZZ.1)工件的定位：圖13.1表示一個在空間完全自由的物體，在這種情況下它具有六個自由度。相對于三根互相垂直的坐標軸XX、YY和ZZ來考慮這些自由度。Thebodycanmovealonganyoftheseaxes;itthereforehasthreefreedomsoftranslation.Itcanalsorotateaboutanyofthethreeaxes;itthereforehasthreefreedomsofrotation.Thetotalnumberoffreedomsissix.Whenworkislocated,asmanyofthesefreedomsaspossiblemustbeeliminated,toensurethattheoperationisperformedwiththerequiredaccuracy.此物體能沿三根坐標軸的任意一根移動；這樣就具有三個平移自由度。它也能圍繞三根坐標軸的任意一根回轉；這樣它又具有三個旋轉自由度?？偟淖杂啥葦的渴橇鶄€。當工件被定位時，必須盡可能多地消除這些自由度，以保證作業(yè)按要求精度進行。Accuracyisensuredbymachiningsuitablelocationfeaturesasearlyaspossible,andusingthemforalllocation,unlessotherconsiderationsmeanthatotherlocationfeaturesmustbeused.Ifitisnecessary,thenewlocationfeaturesmustbemachinedasaresultoflocationfromtheformerlocationfeatures.除非有必要采用另外定位要素的其它考慮，精度可通過盡可能早地加工合適的定位要素并采用它們進行所有定位來保證。如果必要的話，新的定位要素必須作為先前的定位要素的定位結果來加工。2)Theclampingoftheworkpiece.Theclampingsystemmustbesuchthattheworkpieceisheldagainstthecuttingforces,andtheclampingforcesmustnotbesogreatastocausetheworkpiecetobecomedistortedordamaged.2)工件的裝夾：裝夾系統(tǒng)必須使工件對著切削力夾持，而且裝夾力又不能大得引起工件變形或損壞。Theworkpiecemustbesupportedbeneaththepointofclamping,toensurethattheforcesaretakenbythemainframeofthejigorfixture,andontothemachinetableandbed.Whenjigsandfixturesaredesigned,theclampingsystemisdesignedtoensurethatthecorrectclampingforceisapplied,andthattheclampscanbeoperatedquicklybutwithsafety.工件必須在裝夾點下被支撐，以保證這些力由鉆?；驃A具的主框架來承受并傳遞給機器臺和床身。在設計鉆模和夾具時，要同時設計裝夾系統(tǒng)來保證提供恰當的裝夾力，并使裝夾操作快速而安全。DefinitionofaDrillJig

鉆模的定義Adrilljigisadeviceforensuringthataholetobedrilled,tapped,orreamedinaworkpiecewillbemachinedintheproperplace.鉆模是一種確保在工件正確位置進行鉆孔、攻絲或鉸孔加工的裝置。Basicallyitconsistsofaclampingdevicetoholdthepartinpositionunderhardened-steelbushingsthroughwhichthedrillpassesduringthedrillingoperation.Thedrillisguidedbythebushings.它基本上由在淬硬鋼襯套下將零件夾持到位的夾持裝置組成，鉆孔作業(yè)中鉆頭穿過這些襯套，通過它們來導向。Iftheworkpieceisofsimpleconstruction,thejigmaybeclampedontheworkpiece.Inmostcases,however,theworkpieceisheldbythejig,andthejigisarrangedsothattheworkpiececanbequicklyinsertedandasquicklyremovedafterthemachiningoperationisperformed.如果工件結構比較簡單，鉆模可夾持在工件上。然而大多數情況下，工件由鉆模來夾持，并且把鉆模設計成能將工件迅速裝入而在加工后同樣能很快取出。Jigsmakeitpossibletodrill,ream,andtapholesatmuchgreaterspeedsandwithgreateraccuracythanwhentheholesareproducedbyconventionalhandmethods.Anotheradvantageisthatskilledworkersarenotrequiredwhenjigsareused.Responsibilityfortheaccuracyofholelocationistakenfromtheoperatorandgiventothejig.相對于用常規(guī)的手工方法加工孔，鉆模使得鉆孔、鉸孔和攻絲速度快很多而且精度更高成為可能。另一個優(yōu)點是采用鉆模時不需要熟練工人。保證孔定位精度的責任從操作者身上轉移到了鉆模上。Thetermjigshouldbeusedonlyfordevicesemployedwhiledrilling,reaming,ortappingholes.Itisnotfastenedtothemachineonwhichitisusedandmaybemovedaroundonthetableofthedrillingmachinetobringeachbushingdirectlyunderthedrill.Jigsphysicallylimitandcontrolthepathofthecuttingtool.鉆模這個術語只用在服務于鉆孔、鉸孔或攻絲的裝置上。它不固定在使用它的鉆床上，它能在鉆床工作臺上到處移動以使每個襯套都直接位于鉆頭下。鉆模有形地限制和控制鉆削刀具的路徑。Iftheoperationincludesmachiningoperationslikemilling,planing,shaping,turning,etc.,thetermfixtureshouldbeused.Afixtureholdstheworkduringmachiningoperationsbutdoesnotcontainspecialarrangementsforguidingthecuttingtool,asdrilljigsdo.如果作業(yè)還包括其它象銑削、刨削、成型、車削等機加工，則應采用夾具這一術語。夾具在機加工作業(yè)時夾持工件，但它不象鉆模那樣包含引導切削刀具的特殊布置。TypicalJigsandFixtures

典型的鉆模和夾具Typicaldrilljig.Figure13.2illustratesadrillingjigfordrillingfourholesintheflangeofaworkpiecethathasbeencompletedexceptforthefourholes.典型的鉆模：圖13.2所示為一個能在某工件的法蘭上鉆四個孔的鉆模，該工件除了這四個孔外已全部完成。Theworkpiecehasanaccuratelymachinedbore,andislocatedfromtheboreandtheendface,fromacylindricalpost.Thereisnoneedtocontroltherotationalpositionabouttheaxisofthebore,becauseuptothetimewhentheholesaredrilled,itissymmetricalaboutthataxis.此工件有一精確機加工的大孔，因此通過一圓柱體采用該孔和工件端面定位。由于直至鉆這些小孔時，工件都對稱于大孔軸線，所以沒必要控制圍繞大孔軸線回轉的位置。Thefourbushesusedtocontrolthedrillareheldinthedrillplate,which,withthehandnut,isusedtoclamptheworkpieceagainstthebaseofthefixture.四個控制鉆頭的襯套裝在鉆板里，連同手擰螺母一起用于靠著夾具基座夾持工件。Typicalmillingfixture.Figure13.3illustratesasimplemillingfixtureformillingtheslotintheotherwisecompletedworkpieceshown.Theworkpieceislocatedfromtwoofthefourholesinitsbase,andfromtheundersideofthebase.典型的銑削夾具：圖13.3所示為一用于在圖示其它工序都完成的工件上銑槽的簡單銑削夾具。此工件采用其基座上四孔中的兩孔和基座的底面定位。Theworkpieceisclampedinposition,andcutterislocatedagainstthesettingblock,whichprovidessettingorcutterpositionanddepthofcut.工件被夾持到位，銑刀靠著提供安裝或銑刀位置及切削深度的安裝臺定位。Thefixturemustbepositionedrelativetothemachinetable,thisisdonebyengagingthetwotenonsatthebottomofthefixtureintheslotinthemachinetable.ThefixtureissecuredtothemachinetablewithT-bolts,alsoengagingintheslotsinthetable(Fig.13.3).夾具必須相對于銑床工作臺定位，這可通過把夾具底部的兩個凸榫插入工作臺上的槽中來實現。夾具用T型螺栓固定于銑床工作臺，同時與工作臺上的槽接合(圖13.3)。slotn.縫,狹槽,位置,水溝,細長的孔,硬幣投幣口,狹通道,足跡vt.開槽于,跟蹤n.（名詞）Anarrowopening;agrooveorslit:狹槽，縫：狹窄的開口；槽或狹長的裂縫：aslotforcoinsinavendingmachine;amailslot.自動售貨機上的投幣口；投信口Agapbetweenamainandanauxiliaryairfoiltoprovidespaceforairflowandfacilitatethesmoothpassageofairoverthewing.（飛機的）翼縫：主機翼與輔機翼之間的溝