会员注册 | 登录 | 微信快捷登录 QQ登录 微博登录 | 帮助中心 人人文库renrendoc.com美如初恋!
站内搜索 百度文库

热门搜索: 直缝焊接机 矿井提升机 循环球式转向器图纸 机器人手爪发展史 管道机器人dwg 动平衡试验台设计

外文翻译--一个激光束加工(LBM方法)数据库的切割瓷砖 英文版.pdf外文翻译--一个激光束加工(LBM方法)数据库的切割瓷砖 英文版.pdf -- 5 元

宽屏显示 收藏 分享

资源预览需要最新版本的Flash Player支持。
您尚未安装或版本过低,建议您

JournalofMaterialsProcessingTechnology84199847–55AlaserbeammachiningLBMdatabaseforthecuttingofceramictileI.Black,S.A.J.Livingstone,K.L.ChuaDepartmentofMechanicalandChemicalEngineering,HeriotWattUni6ersity,Riccarton,EdinburghEH144AS,UKReceived13December1997AbstractThispapercoversthecuttingofcommerciallyavailableceramictilesusingaCO2lasercuttingmachine,withtheobjectofproducingalaserbeammachiningLBMdatabasethatcontainstheessentialparameterinformationfortheirsuccessfulprocessing.Variouslasercuttingparameterswereinvestigatedthatwouldgenerateacutinceramictilewhichrequiredminimalposttreatment.Theeffectsofvariousshieldgases,ofmultipasscuttingandofunderwatercuttingwerealsoexamined.©1998ElsevierScienceS.A.Allrightsreserved.KeywordsCO2LasercuttingCeramicmaterialsAdvancedmanufacturingprocesses1.IntroductionandbackgroundManualmethodsofcuttingceramictilesareverysimilartothatforglass,i.e.scribingthematerialswithtungstencarbidetippedcutter,followedbytheapplicationofabendingmomentalongthescribedlinetoinitiatecontrolledfracture.However,manualtechniquesarelimitedtostraightlinecuttingandrelativelylargeradiuscuts.Internalandundercutprofilesarenearlyimpossibletoproducewithscoringalonewiththepossibleexceptionofinternalcirclesmoresophisticatedmethodshavingtobeappliedtoachievetheseprofiles.Traditionally,diamondsaw,hydrodynamicwaterjetorultrasonicmachiningareusedtocreatecomplexgeometriesinceramictiles,buttheseprocessesareverytimeconsumingandexpensive.Forexample,typicaldiamondsawcuttingspeedsareintheorderof20mmmin11,whileultrasonicdrillingofAl2O3takesover30sperhole2.ThemostcriticalfactorarisingfromuseofaCO2lasertocutceramictilesiscrackdamage,whichisessentiallycausedbyahightemperaturegradientwithintheceramicsubstrateduringthecuttingprocess.Thesecracksreducethestrengthandaresourcesforcriticalcrackgrowth,whichmayresultinpartialorcompletefailureofthetilesubstrate3.Thusareductionofprocessinducedcrackformationisparamountfortherealisticcommercialuseoflaserstocutceramictiles.2.LasercuttingparametersLasermachiningofanymaterialisacomplexprocessinvolvingmanydifferentparametersthatwhichallneedtoworkinconsorttoproduceaqualitymachiningoperation4,parameterssuchasilaserpowerinputiifocalsettingiiiassistgastypeandpressureivnozzleconfigurationvworkpiecethicknessandvioptophysicalproperties.Previousresearchwithintheauthorsdepartment1,5,6hasalsodemonstratedthecriticalityoftheaboveparametersinefficientlasercutting.2.1.LaserpowerLaserpowerdependsonthetypeoflaserused.Fortheworkreportedinthispaper,aFerrantiMF400CNClasercutterwasemployed,ratedatapoweroutputof400W.However,duetoupgrading,themaximumbeampowerachievablewasbetween520andCorrespondingauthor.Fax441314513129emaili.blackhw.ac.uk0924013698seefrontmatter©1998ElsevierScienceS.A.Allrightsreserved.PIIS0924013698000788I.Blacketal.JournalofMaterialsProcessingTechnology84199847–5548530WincontinuouswaveCWcuttingmode.ThelaseralsohadtheabilitytoworkinpulsemodePMandsuperpulsemodeSPMFig.1.Todeterminetheequivalentpoweroutputduringpulsingoperation,apowerversespulsingchartwasusedinconjunctionwiththefollowingbasicequation9PrPlPsf1PlPrAlthoughthelasercuttercouldoperatebetweenfrequenciesof50and5000Hz,avalueof500Hzwasrecommendedinpreviouswork1,5.Sincethissettingprovedtobesuccessful,onlylimitedinvestigationintootherfrequencieswascarriedoutat250Hz,750and100Hz.2.2.CuttingspeedTheCNCtableusedwiththeFerrantiMF400lasercutterhadamaximumfeedrateof10000mmmin1.Previouswork6indicatedthatfeedratesabove6000mmmin1provedtobeunstableforanystandardisedtesting.Theoptimumcuttingspeedvariedwiththepowersettingand,moreimportantly,withthethicknessoftheworkpiece.2.3.ShieldgastypeandpressureCompressedair,argon,nitrogenandoxygenwereusedasshieldgasesduringcutting,withpmax4bar.Differentshieldgaseswereusedtoexaminedtheireffectoncutqualityafterprocessing,sincetheshieldgasnotonlycoolsandcutedgesandremovesmoltenmaterial,butalsogeneratesachemicalreactionwiththesubstratematerial7.Theresultsofthischemicalreactiondifferforeachtypeofshieldgasused.Fortestpurposespwasvariedinstepsof0.5barfrom1to2.5bar,theninstepsof0.2barfrom2.6bartothemaximumattainablegaspressure.2.4.NozzleconfigurationThenozzlediametercontributesdirectlytothemaximumachievablegaspressureandhencetothemassflowrateofthegaswasimportantfortheeconomicsofcutting,especiallywhenusingcylindersofargonandnitrogen.Onlycircularprofilesforthenozzleexitswereavailable0.6mm5Ns520mm,butthisuniformnozzleexitgeometryallowedcuttinginanydirection.2.5.NozzleheightandfocalpositioningTheheightatwhichthenozzlewassetwasgovernedbythepositionofthefocalpoint.TheFerrantiMF400lasercutteronlypossessedalongfocallengthof110Fig.1.Cuttingmodes.mmoriginallyashortfocallengthof46mmwasavailablebeforeupgradingandthislengthcouldbealteredby95mm.Ifthenozzleheightwasincorrectlysetthebeamwouldclipthenozzleandreducetheequivalentpoweroutputtotheworkpiece6.Forthebulkofthetestingthefocalheightwassetsothefocalpointwasonthejob,i.e.onthetopsurfaceoftheworkpiece.Thisconditionobviouslygovernedthepositionofthenozzleabovetheworkpiece.3.ExperimentalprocedureSixtypesofSiAl2O3basedceramictileswereexaminedTable1,originatingfromdifferentcountries.Notethatthecompositionofthetilesvaried,asdidthethickness,butallpossessedasurfaceglazeandinthecaseofthe7.5,8.6and9.2mmSpanishtilestheglazewasdoublelayered.3.1.SetupprocedureSincetherewasaneedforstandardtestingconditions,thefollowingprocedurewasimplementedbeforethestartoftestingithebeampowerwasvalidatedtospecification,i.e.520–530WdevelopedatfullpowerCW,althoughthisdroppedtoaround50WafterTable1TypesofceramictileusedtsmmTiletypeBodycolour3.7BrazilianWhite4.7WhitePeruvianLightredItalian5.2SpanishRed5.74Spanish7.5RedRedSpanish8.69.2RedSpanishI.Blacketal.JournalofMaterialsProcessingTechnology84199847–5549about1hoftestingiithenozzleandthefocallenswerecheckedtoensurethattheywereingoodcondition,i.e.cleanandundamagediiitheshieldgaspressureregulatorandshieldgastankswereturnedontopreventdamagetothefocallensivthelaserbeamwascentredwithinthenozzleusingasquaretest,alowerenergyinputinPMbeingusedtocutasquareonamildsteel,thesparkingdensitythatresultedfromcuttingbeingcheckedtoseeifitwasequallydistributedaboutthecutlineandvthefocalpointwassetforitsdesiredpositioning,i.e.onthejob.3.2.TestingAstraightlinetestSLTwasusedtoevaluatethevariablelaserparametersforfullthroughcuttingFTC.Angularcuttingwasconfiguredtoinvestigatehowthematerialreactedduringcuttingoftightgeometry.Circulartestingandsquaretestingweredevisedtodeterminetheeffectsresultingfromcuttingvariousgeometries.TheSLTallowedforthecombinedtestingoftwoseparateparametersononetestpiece,uponcompletiontheresultsbeingpresentautomaticallyinacuttingmatrixintheformoftheresultingcuts.PandVarethemostimportantlaserparameters,astheydictatetheamountofenergyinputperunitlengthofcut,thereforetheywerepairedfortheSLT,aswerepandNSwhichgovernthemassflowrateoftheshieldgas.ForthePVtestruns,thepowerwasheldconstantwhilethecuttingspeedwasincreasedalongthecutFig.2a.ThelengthofcutatconstantcuttingspeedhadtobeofsufficientmagnitudetoaccommodatetheaccelerationordecelerationoftheCNCtablebetweenfeedchangespreviouswork6indicatedthat50mmwasadequate.Interpretingtheresultswasmadeeasierduetotheirtabularformat,withthecuttingmatrixshowingclearlyanytrendsorpatternsoccurringduetothechangesinparametersettings.TheSLTalsoallowedalargenumberofcutstobecarriedoutoverashorttimeframe.Thisprovedadvantageous,asthelasertendedtodriftfromitsinitialsettingswithtime.Precautionshadtotakentoavoidlocalisedheatinginthetilefromcontinuouscloseproximitycutting,asachangeintilebodytemperaturewouldinvalidateanyresultingdata.Initially,a20mmseparationbetweencutswasusedandthisprovedsufficient.Inordertostudyhowclosethecutscouldbemadetoeachother,theseparationbetweencutswasreducedbyincrementsof2mmfromaninitial20mmspacing.DuringtheSLTtheotherlaserparametershadtobeheldconstant6.ForPversusV,fwasheldat500HzwithNS1.2mmandp3bar.Thebeamfocalpointremainedonthejob.TheresultsfromthePVcuttingmatrixdeterminedthefixedvaluesforthecuttingspeedandpulsesettingsforthesucceedingSLT.FortheNSpFig.2.Testingconfigurationastraightlinetestingbangulartestingccirculartestingdsquaretesting.cuttingmatrix,thenozzlesizeremainedconstantalongthexaxisrefertoFig.2awhilepwasincreasedinstepsof0.2barfrom2barintheyaxisthecutseparationremainedconstantat20mm.Anewmatrixwascreatedsubsequentlyforeachnozzlesize.AngulartestingFig.2bwasusedtoinvestigatehowthecutmaterialreactedtosustainedexposurefromthelaserbeamduringthemachiningoftightgeometriesi.e.whereseveralcutsaremadeincloseproximitytoeachother.TheproximitytestmentionedforSLTdetermineshowcloseparallellinescanbecuttoeachother,whereasangulartestingisusedtodeterminehowthecuttingofacuteangleseffectsthecutquality.Theanglescutfromaworkpiecewerereducedfrom45°to10°andthecorrespondingsurfacefinishqualitySFQwasnoted.I.Blacketal.JournalofMaterialsProcessingTechnology84199847–5550Table2MultipasscuttingparametersPlCuttingmodePsNo.ofpassesLastcutCW60FTC9000100SPMFTC100Table3GradingofSFQGrading1Nocrackinginsurfaceglaze,solidsharpcutedgeMinimalglazecrackingWcB2mmwithslight2lossofsharpnessincutedgeMediumcracking2mmBWcB4mmandslight3damagetounglazedtilesubstrateSignificantdamagetoglazecoatingWc\6mm,4heavydamagetounglazedsubstratecausingflakingintheglazedsurface5Sameas4butwiththeformationofcracksinthetilesmainbodyleadingtostructuralfailureinapartofthetileusuallyattheendofacutorwithin8mmofthetileedge.TherearetworeasonsforconductingsquareandcirculartestingFig.2canddfirst,todeterminetheoptimummethodoflaserbeamintroductiontointernalcutprofilesandsecondly,todetermineiftherewasanylimitationinthedimensionofthesizeofsquareorholecut.Ifnotcorrectlyintroduced,thelaserbeamwouldcauseaninternallycutprofiletofailatthepointofintroduction,duetothebriefbutexcessivethermalgradientinducedfromcuttingi.e.thermalshock.Therefore,utilisingmethodsofbeamintroduction,suchastrepanning,ontoaprofileenabledcomplexgeometriestobeinvestigated.Whatalsobecameapparentduringtestingwastheimportanceofthepositionofbeamextractionfromthecutprofileandthepositionofthebeamstartingpointrelativetothegeometry,i.e.whetheritwasatacorneroronastraightedge.3.3.MultipassandunderwatercuttingMultipasscuttingwasbegunwithalowpowerP100Wlaserbeam.Thefirstpassproducedawelldefinedblindkerfinthesubstrate,followedbyasecondpasstocutdeeperandsoon.Theprocesswasrepeateduntilthekerfwasabout20mmdeepandthenthelaserpowerwasswitchedto500WanddothefinalFTC.Theobjectiveofmultipasscuttingwastoreducethermaloverloadbyuseoflessinputenergyperunitlength.TheparametersusedinthistestaregiveninTable2.Underwatercuttingwasconductedwiththeobjectiveofreducingtheinfluenceofheataroundthecutareaandalsotoexaminedtheeffectoncutqualitythroughacceleratedheatdissipationusingwater8.Theceramictilewasplacedunderwaterandthenozzlewasalsodippedinwater,theshieldgaspressurepreventinganywaterfromenteringthenozzlejetchamber.4.CutqualityMaterialproperties,laserparametersandworkpiecegeometryhaveasignificanteffectonthefinalresultofthelasercuttingprocess.Cutqualityisessentiallycharacterisedbysurfaceroughnessanddrossheight,whereascracklengthdictatesthestrengthreductioninthesubstrateFig.3.TheoverallSFQattheglazesurfacewasclassifiedaccordingtothegradingscalegiveninTable3.Therefore,thequalityofthecutsurfaceandedgeweremeasuredwithrespectedtoisurfaceroughnessiisurfacefinishandiiidrossadherence.Fig.3.Qualitycriteriaforthelasercuttingofceramictiles.
编号:201311171105565701    大小:246.72KB    格式:PDF    上传时间:2013-11-17
  【编辑】
5
关 键 词:
教育专区 外文翻译 精品文档 外文翻译
温馨提示:
1: 本站所有资源如无特殊说明,都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
2: 本站的文档不包含任何第三方提供的附件图纸等,如果需要附件,请联系上传者。文件的所有权益归上传用户所有。
3.本站RAR压缩包中若带图纸,网页内容里面会有图纸预览,若没有图纸预览就没有图纸。
4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
5. 人人文库网仅提供交流平台,并不能对任何下载内容负责。
6. 下载文件中如有侵权或不适当内容,请与我们联系,我们立即纠正。
7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。
  人人文库网所有资源均是用户自行上传分享,仅供网友学习交流,未经上传用户书面授权,请勿作他用。
0条评论

还可以输入200字符

暂无评论,赶快抢占沙发吧。

当前资源信息

4.0
 
(2人评价)
浏览:16次
英文资料库上传于2013-11-17

官方联系方式

客服手机:17625900360   
2:不支持迅雷下载,请使用浏览器下载   
3:不支持QQ浏览器下载,请用其他浏览器   
4:下载后的文档和图纸-无水印   
5:文档经过压缩,下载后原文更清晰   

相关资源

相关资源

相关搜索

教育专区   外文翻译   精品文档   外文翻译  
关于我们 - 网站声明 - 网站地图 - 友情链接 - 网站客服客服 - 联系我们
copyright@ 2015-2017 人人文库网网站版权所有
苏ICP备12009002号-5