外文翻译--夹头.doc

附录A外文文献及其翻译COLLECTCHUCK1.IntroductionToimproveproductivityinmicro/meso-scalecomponents,researchershavefocusedondevelopingminiaturizedmanufacturinginstruments,suchasmicro-machinetools.Theseminiaturizedsystemsareexpectedtosaveenergyandbeeasilyreconfigurable.Thefirststepinmicro-manufacturinginstrumentsisminiaturizingthecorrespondingsubsystems.Inparticular,micro-machinetoolsformaterial-removalprocesseshave,asakeysubsystem,amicro-spindleunitthatmustachievehighrotationalspeedswhilemaintaininggoodrotationalaccuracyformicro-featuremachining.Indevelopingmicro-spindleunits,acriticalproblemisminiaturizationofthetool-clampingpartthatholdsthetoolinthespindle.Approachesforscalingdownconventionaltoolclamps,suchasthecollet-chuck,hydraulicchuck,andshrink-fitmethods,maybelimitedbytheirinherentlycomplicatedstructuralandoperationalmechanisms.Incollet-chucks,ataperedcolletandcollet-pullingdevice,suchasaspringandascrew,mustbeincludedinthemicro-spindle.Inaddition,ataperedcolletcausestolerancestackup,whichmayincreaserotationerrormotion.Hydraulicchuckshaveanon-axisymmetricstructureinsidethespindleduetotheneedforanadjustingscrewandoilpaths.Theseelementsunbalancetherotormass,increasingrotationerrormotionathigh-speedrevolution.Finally,shrink-fittoolholdersrequirespecificequipmenttoheatthedevicetoahightemperaturetounclampatool,equipmentthatistooexpensiveandtoolargeforusewithmicro-machinetools.Onepossiblewaytoavoidtheseproblemsistoincorporateashapememoryalloy(SMA).SMAshaverecentlybeenusedinvariousapplications,suchasactuators,fasteners,bonefixaters,andsoon713.Theyarelightweight,alloweasyandpreciseinstallation,yieldexcellentreliability,andprovidegoodimmunityagainstshockandvibration.ByemployingSMAforatoolclamp,theclampcanbesimplifiedbecausetheSMAdirectlyprovidestheradialtool-clampingforceonthetoolholder.Duetothissimplestructure,furtherminiaturizationispossible,soithasanadvantageofgoodimmunityagainsttheeffectofcentrifugalforce.Inaddition,unlikeacollet-chuck,anSMA-basedtoolclampdoesnotrequireacollettodevelopclampingforce；thiseliminatesthetolerancestackupthatresultsfromthecollet.TheSMA-baseddevicealsohasanaxisymmetricstructuralconfiguration,unlikeahydraulicchuck,whichminimizestheeffectofmassunbalance.Finally,thetoolclampcanswitchbetweentheclampedandunclampedstatesbyusingasimpledevicetoregulatesmallchangesintemperature,therebyeliminatingtheneedfortheexpensiveheatingequipmentusedinshrink-fitmechanisms.Inthisstudy,wedevelopedatoolclampbasedonSMAforapplicationsinmicro-spindleunits.First,wedevelopedthebasicconfigurationofthetoolclampusinganSMAring,anddescribedtheprincipleofclamping/unclampingthetoolmathematically.Second,weconductedthree-dimensional(3D)finiteelementmethod(FEM)analysestoassessthecharacteristicsoftheclamping/unclampingoperationsandtheeffectofcentrifugalforce.Next,wedesignedandbuiltaprototypeoftheSMA-basedtoolclamp.Then,weexperimentallyevaluatedthetimeneededforclamping/unclampingoperationsandthetool-clampingforce.Finally,weusedtheprototypetoconductamill-machiningtesttoconfirmthatitwasunaffectedbycentrifugalforceathighrotationalspeeds.2.Principle2.1.ShapememoryalloysSMAsareauniqueclassofalloysthatarecharacterizedbytheshapememoryeffect.AnSMAthatisdeformedinalow-temperaturephase,calledthemartensiticphase,canrecoveritsoriginalshapeuponheatingtothereversetransformationtemperature,wheretheSMAenterstheausteniticphase.IftheSMAisimpededbyanexternalmechanicalstructureasitisreturningtoitsoriginalshape,recoverystressesaregenerated.TherelationshipsbetweenstressesandstrainsinSMAmaterialsareafunctionoftemperature15.Inthelow-temperaturephase,SMAshaveasmallerYoungsmodulusandyieldstrengththanathighertemperatures.Thatis,SMAsinthemartensiticphasearemoreeasilydeformedelasticallyorplasticallythanthoseintheausteniticphase.Thus,anSMAsrecoverystresscanbeadjustedbycontrollingtemperature.Basedonthesephenomena,anSMAcanbeusedinatoolclamp.2.2.ConfigurationFig.1showsthestructuralconfigurationofourSMA-basedtoolclamp.Itconsistsofonlytwoparts:atoolholderintheendofthespindle,andaclosedSMAring.Thetoolholderhasacentralholeinwhichatoolisinstalled,andfourlateralslots.TheSMAringisplacedaroundtheoutsideofthetoolholder.Thelocationofthisringisdeterminedbythesurfaceboundarybetweenthedifferentdiametersofthecomponentsofthetoolholder,sotheclampingforceoftheSMAringcanbeprovidedinthedesiredlocationanddirection.ItisimportantthattheSMA-basedtoolclampcannotonlyclampthetoolbutalsounclampwheneveratoolchangeisrequired.Toachieveclamping/unclamping,aninterference-fitbetweenthetoolholderandtheSMAringwasdeveloped.Thisinterference-fitconstrainstherecoveryoftheSMAring,resultinginarecoverystress,sothatarecoveryforceactsonthetoolholder.WhentheSMAisintheausteniticphase,thetoolholeisfurthershrunkbytherecoveryforce.However,whentheSMAisinthemartensiticphase,thetoolholecanreturnalmosttoitsoriginalshapethroughtheelasticforceofthetoolholder,becauseinthisphasetheSMAhasminimalrecoveryabilityandiseasilydeformedbyexternalforces.Inotherwords,intheausteniticphasetheSMAremainsaboveitsreversetransformationtem-perature,ensuringthetoolremainsclamped,andduringthecoolingprocedurethetoolunclampedinthetoolholdercanbeinstalledoruninstalled.翻译为了提高微/中尺度元件的生产力，研究人员专注于开发小型化生产工具，如微机械工具，这些小型化系统有望节省能源和易于识别文字.微制造工具的第一步是小型化相应的子系统.尤其是微机械材料，清除过程工具，作为一个关键子系统，一个微型主轴单元，必须达到较高的旋转速度，同时保持对微加工功能良好的旋转精度。在发展微型主轴单元，一个关键问题是该工具夹紧部分保存在主轴方法的缩减，如传统的工具夹夹头，卡盘，液压卡盘，收缩后接的方法，工具，小型化，可能受到他们本身复杂的结构和运作机制.夹头，卡盘，一个锥形夹头及夹头拉设备，一个螺丝钉，都必须在微主轴里.此外，包括有限公司，锥形夹头的原因叠层宽容，这可能会增加旋转误差偏移.液压夹头主轴内有一个由于对一个调整螺丝和石油路线.这些元素不平衡转子的质量需要非轴对称结构，增加高旋转速度的革命运动误差。最后，收缩接刀柄需要特定的设备加热装置，高温下松开的工具，设备过于昂贵，对于微机械工具.一个使用的方式来避免这些问题太大，是把一个形状记忆合金（SMA）。形状记忆合金，最近在各种应用，如驱动器，紧固件，骨等7-13。它们是轻量级的，使用，允许安装方便，准确，产量出色的可靠性，并提供防冲击和雇用一个工具钳SMA的振动.通过良好免疫力，钳可以简化，因为直接提供了SMA径向工具钳的工具支撑.由于这个简单的结构受力，进一步小型化是可能的，因此它针对该离心力.优势除了免疫效果好，不像一个夹头，卡盘，一个SMA型工具钳不需要夹头夹紧力的发展，这消除了公差层叠，形状记忆合金基于设备还具有轴对称结构的配置，不同的是液压卡盘，能最大限度地降低质量效应不平衡.最后，工具钳钳夹之间可以松开开关状态通过使用简单的设备调节温度的微小变化，从而省去了昂贵的取暖收缩适合机制.利用这一研究设备的需求，我们开发了一种工具钳形状记忆合金为基础的微主轴units.First应用，我们开发的基本配置使用的工具钳形状记忆合金环，并介绍了夹紧原则/松开工具机制.第二，我们进行了三维（3D）的有限元法（FEM）分析，评估的夹紧/松开业务特点和效果离心力.然后，我们设计并建立了形状记忆合金为基础的工具钳.原型，我们实验评估夹紧/松开操作和工具钳力.最后所需的时间，我们使用原型进行磨机械加工测试，以确认它是由高速旋转的速度在离心力的影响。2.原理2.1.形状记忆合金形状记忆合金是一组由形状记忆合金形状记忆效应.一个是在低合金低温相变形的特点独特的类，称为马氏体相，加热后可以恢复到反向相变温度，形状记忆合金在进入其原来的形状奥氏体相.如果SMA是由外部的机械结构阻碍，因为它是返回到原来的形状，恢复压力和生产之间的关系，形状记忆合金材料的应力和应变是温度的函数15。在低温阶段，形状记忆合金具有较小的弹性模量和屈服强度比在较高温度.也就是，在形状记忆合金马氏体相更容易变形弹性或塑性高于奥氏体.因此，一个形状记忆合金的回复应力可以调整通过控制这些现象，基于这些现象，SMA可以用在工具钳上。2.2.配置图1给出了我们的形状记忆合金为基础的工具.结构配置只有两部分组成：一个在年底刀架主轴，