先进制造技术-施平五单元

1、Advanced Manufacturing Technology先进制造技术施平Part 51Contents1.IntroductiontoAMT2.Computerandcommunication3.Computer-aidedengineering4.Automation5.Modernmanufacturingtechnologies25.ModernmanufacturingtechnologiesBasictheoryand moderntechnologyTechnological changeinmanufacturing engineering is phenomenala

2、nd speedingBasictheories(likemetalcutting theory)are thefoundation of thesophisticated technologies35.ModernmanufacturingtechnologiesPrecisionengineeringQuality improvementsofproductsrequirestheenhancementofprecision of productionsystem5.1Modernmanufacturingtechnologies-Precisionengineering45.Modern

3、manufacturingtechnologiesBasicdefinitionsAccuracyA quantitativemeasure of thedegreeofconformancetorecognizednationalorinternational standardsofmeasurementRepeatabilityA measureofthe abilityofamachine to position atoolsequentiallywithrespect to workpieceundersimilar conditionsResolutionTheleastincrem

4、ent of ameasuring deviceTheleastsignificantbit on adigitalmachine5.1Modernmanufacturingtechnologies-Precisionengineering55.ModernmanufacturingtechnologiesMotionSlideSpindleRigidelementWetreatindividual elementasrigidbodyFlexiblestructureThewholestructure maybeflexibleduetodeflectionsand joints5.2Mod

5、ernmanufacturingtechnologies-Precisionengineering65.ModernmanufacturingtechnologiesRigidbody motionanderrorTheslide5 constraints (Y,Z movement along Y, Z,rotationaboutX,Y,Z )1 DOF( movement along X)Wecontrol X, while treating theother5 DOFsaserrors5.2Modernmanufacturingtechnologies-Precisionengineer

6、ing75.ModernmanufacturingtechnologiesCategories ofsources of errorsofa machinetoolGeometricerrorsCausedbylackofstraightnessinslide-ways,staticdeflection of machinetool,angularerrorsDynamic errorsCausedbymachinetool vibration(chatter)Inherentfrequency(avoidthe 1st,2nd,)andresonanceStiff,lightweight,w

7、ell-dampedmachine toolhas lessdynamicerrorWork-piece effectsMachine tooldeflectioncausedbyfixing andcutting forcesduringcuttingprocessInertialeffects duetomotion: over-shootonalinearmotion;periodicdeviations causedbydynamic unbalanceduetopartasymmetryaboutrotationalaxis(likethespindleaxis)Thermal er

8、rorsExpansionwhenheated, contraction whencooledTemperaturecontrol:air-condition,warming-up timebefore operation5.2Modern manufacturingtechnologies-PrecisionengineeringPerfect machinewithouterrorsdoesnotexistAllmachinetoolshave geometricerrors85.ModernmanufacturingtechnologiesTraditionalfinishingoper

9、ationsHoningHole surfaceprocessingRadiallyfloating,axiallyreciprocating movement5.3Modern manufacturingtechnologies-finishingoperation95.ModernmanufacturingtechnologiesTraditionalfinishingoperationsSuper-finishingPressureforcevery lightStonestrokeveryshort5.3Modern manufacturingtechnologies-finishin

10、goperation105.ModernmanufacturingtechnologiesTraditionalfinishingoperationsLappingAbrasiveparticlesinaslurrySurface finish0.0250.1mPolishingNon-traditionalfinishing operationChemicalmechanical polishingA chemical reaction occurred(example:siliconwaferpolishing)Electro-polishingElectrolyteattacks the

11、projectionsandpeaksonthe work-piecesurfacetogetafine surfacePolishingprocessusingmagneticfields5.3Modern manufacturingtechnologies-finishingoperation115.ModernmanufacturingtechnologiesAimofCoated toolsTocope withthe uniqueproperties of newmaterialsHigh srength, Toughness,ChemicalpropertiesCoating ma

12、terialGeneral characteristicsHigh hardnessChemicalstabilityand inertnesstothework-piecematerialLowthermalconductivityGood bondingtothe substratetoprevent flakingLittleornoporositycommonlyused coatingmaterialsTiN, titanium nitride: lowfrictioncoefficient,highhardness,resistancetohigh temperature,good

13、 adhesion to substrate.PerformswellathighercuttingspeedTiCtitaniumcarbide:similarpropertiesTiCN titanium carbonitride:goodwear resistancewhencutting carbonsteel,alloysteel, castironAl2O3AluminumOxide:low thermalconductivity,high hothardness,wearresistance5.3Modern manufacturingtechnologies-coatedtoo

14、ls125.ModernmanufacturingtechnologiesSubstratematerialHSS, highspeedsteelCementedcarbideCeramicSuper-hard materialCoating processCVD, chemical vapor depositionChemicalVaporDeposition is chemical reactionswhichtransformgaseousmolecules, calledprecursor, intoasolidmaterial,inthe formofthinfilm or powd

15、er,onthe surfaceofasubstrateIna typicalCVD process, thewafer(substrate)isexposed to oneormore volatile precursors, which react and/ordecomposeonthe substratesurface to producethe desireddeposit.Frequently,volatileby-productsare alsoproduced, which areremoved by gasflow throughthe reaction chamber5.3

16、Modern manufacturingtechnologies-coatedtools135.ModernmanufacturingtechnologiesPVD, physical vapor depositiona varietyofvacuum depositionand is ageneralterm usedtodescribeany of avarietyofmethods to depositthinfilmsbythecondensation of avaporized formofthe material ontovarioussurfaces.The coatingmet

17、hod involves purelyphysicalprocessessuchashigh temperature vacuumevaporationorplasmasputterbombardmentratherthaninvolvingachemicalreactionatthesurfacetobecoatedasinchemicalvapordeposition5.3Modern manufacturingtechnologies-coatedtoolscomputersimulation of thebasicphysicalprocess underlyingphysicalva

18、pour deposition: asingle Cu atomdeposited on aCusurface145.ModernmanufacturingtechnologiesLubricatingcoating materialA coatingtoenhancelubricationincutting (especially in drycutting)Coating materialMoS2(molybdenumdisulfide)Multilayer coatingTogetacombinedpropertyofthecuttingtoolCVD+PVDTiN+ MoS2Diamo

19、nd-coatedtoolDiamond:superhard,idealmaterialformachining abrasive,nonferrous metalsandnonmetalliccomposites5.3Modern manufacturingtechnologies-coatedtools155.ModernmanufacturingtechnologiesFactors leadtotoolfailuresExtreme heat(cuttingedgetemperatureexceeds 1000)Degradesbinders andothertool constitu

20、entsTriggersdetrimentalchemicalreactionsbetweentool andwork-pieceHigh pressureAbrasionShockthermal shockmechanical shockBasicfailure mechanismsCraterwearThermal deformation andcrackingNose wearBuilt-upedgeFractureFlankwear5.4Modern manufacturingtechnologies-failure mechanismofcutting tools165.Modern

21、manufacturingtechnologiesHigh speed machineHigh spindlespeedand feedspeedSpindle speed exceeds10,000 rpmBenefit of HSMImprovedperformanceandproductquality (such as finer finish)Reduced productiontime,lowercostFactors hindershighspeedWeightofmobile componentOvershoot, tip-upofmachineCenterofgravityLo

22、wercenterofgravitycanreduce problemliketip-upofmachineRigidity,stabilityKeytoHSMAxis driveLinearmotorismorerigidthan ballscrew,gearbox,etc.AccuracyMachine configurationMachine programming,trainingandmaintenance5.5Modern manufacturingtechnologies-high speed machining175.Modernmanufacturingtechnologie

23、sHardnessofmaterialDefined by itsresistance to permanentdeformationIts thecombinationofelastic andplastic property thatdetermine amaterialsresistance to permanentdeformation555HRC65HRCTensile strength up to 2400MPaHard turningSmalldepthofcutand feedthough,much fasterthan grindingrigidmachine tool, a

24、ndhardertools(CeramicorCBN ,orcubicBoronNitride)makeshardturning possibleProblemstoberedressWorkpiecemicrostructureinfluenced(residualstress andover-hardened)Tool wearand workpiecesurface qualityHard millingTakesover thework of machining4564HRCtoolsteelbyEDM(electricaldischarge machining)Machine too

25、l(similarrequirementtoHSM)andcuttingtool (coatedtoolwith TiCN, TiAlN,with goodwear,heatresistance ,hardness)5.6Modern manufacturingtechnologies-hard partmachining185.ModernmanufacturingtechnologiesPresentations topics(Eachgroup48students)PrecisionmachiningDryornear-drymachiningCreep-feed grindingMac

26、hiningofengineeringceramics5.6Modern manufacturingtechnologies195.ModernmanufacturingtechnologiesCryogenicprocessingHeat treatmenta methodused to alter thephysical,and sometimeschemicalproperties of amaterial.Themostcommonapplicationismetallurgical.also usedinthe manufacture of manyothermaterials,su

27、ch as glass.205.ModernmanufacturingtechnologiesHeat treatmentHeat treatmentinvolvestheuse of heatingorchilling, normally to extremetemperatures,toachieve adesiredresultsuchashardeningorsoftening of amaterial.Intentionally:heat treatmentapplies to processeswheretheheatingandcoolingaredoneforthe speci

28、fic purposeofalteringpropertiesIncidentally:heatingandcoolingoftenoccurduringothermanufacturingprocessessuchashotformingorwelding.215.ModernmanufacturingtechnologiesCommonHeattreatmentAnnealing:退火a techniqueused to recovercoldwork（冷作作）andrelaxstresseswithin ametalQuenching（Hardeningand tempering)Toh

29、ardenbyquenching,a metal (usually steel or castiron)mustbeheatedintotheausteniticcrystal phase andthen quicklycooled.225.ModernmanufacturingtechnologiesCommonHeattreatmentTempering.Untempered martensite, while veryhard,istoo brittletobeuseful formost applications.Most applicationsrequire thatquenche

30、dpartsbetempered(heattreatedata lowtemperature,often150 C) to impartsome toughness.235.ModernmanufacturingtechnologiesCommonHeattreatmentSelectivehardeningallowdifferentareasofasingleobject to receivedifferent heattreatments.also calleddifferentialhardening.Commonlyused in highqualityknivesand sword

31、streatment.TheChinese“jian”isone of theearliestknownexamples245.ModernmanufacturingtechnologiesCryogenicprocessingCryogenicsThebranchesofphysicsandengineeringthatinvolve thestudyofvery lowtemperatures, howtoproduce them, andhowmaterials behaveatthosetemperatures.255.ModernmanufacturingtechnologiesCr

32、yogenicprocessingCryogenicprocessingCryogenicprocessingisnotasubstitute forheat treatment,but ratheranextensionofthe heating-quenching-temperingcycle.265.ModernmanufacturingtechnologiesFeature of manufacturinginaerospace industryLowvolumeHigh reliability,precisionrequirementsMaterialwith highstrengt

33、h, light weight,difficult to machineStainlesssteel(for highweararea)Titanium,high-nickelsteelalloy(Goodpropertyatelevatedtemperature,forcriticalload-bearing component,likeengine)Aluminum(for structuralcomponent)Alloysteel(for highstrength, highimpact application,like landinggear)Challenges of machin

34、ingoftitaniumalloyWork hardening:Tialloycan be workhardenedSharpcutting edge, small feedand depth of eachcut,Userigidmachinetool,avoidingchatter to getgood finishDeflection:TihasalowmodulusofelasticityReactivity:TiismorereactivetotoolManufacturing foraerospaceindustry275.ModernmanufacturingtechnologiesLargepart handlingDifficultiesFlex andwarpManufacturing andassemblya radar cover of asurveillan