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ZHENGTian-chang WANGMinXUXiong-guo(ShanghaiElectricPowerGenerationEquipmentCo., .ShanghaiTurbine Shanghai200240, :HTGRnuclearturbinerotorisoneofthemostimportantpartsofanuclearturbineunit,whichbelongstoheavymonoblocrotor.Thequalityofnuclearturbinerotorysavitalroleonthesafetyandefficiencyofanuclearturbineunit.Toimprovetheperformanceandincreasethefatiguelifeoftherotor,aseriesofresearchesonrotorprocessesandprecisioncontrolaredone,includingtheprecisioncontrolofT-typerotorbladegroove;therollingofrotorjournalbaffle;themillingprecisioncontroloftheworkingsurfaceofChristmastreerotorbladegroove;therollingprecisioncontroloftheworkingsurfacecornersofChristmastreerotorbladegroove,andthemachiningwayofT-typelastbladeinsertiongroove.Accordingtotheresearchonrotorprocessesabove-mentioned,thispagegivesthewaysofHTGRnuclearturbinerotorkeyprocessesandprecisioncontrol,andtheHTGRnuclearturbinerotorwillbefinishedwithagood:HTGR;rotorkeyprocesses;precisionThestructureofHTGRrotoriscomplicated.Inordertoimprovetheanti-fatigueabilityofthehightemperaturepart,thedesignrequirementsoffilletonHTGRrotortransitionsurfaceishigh.Rotorbladegroovehasthreetypes:T-type,DoubleT-typeandChristmastreerotorbladegroove.TheprofileofT-typebladegroovehasmanydimensions.DoubleT-typeismorenarrowanddeeper,soitrequirementshighmachiningaccuracy.Inordertoreducethedynamicstressofbucketrootandimprovetheendurancelifeofthegroove,theworkingfaceoflastbladegrooveneedtoberolled.Rollerburnishingyieldsasignificantincreaseinthenumberofcyclessustainablewithoutfractureandthusaconsiderableincreaseintheendurancelimit.TheprocesstechnologyofHTGRrotorisverycomplicatedanditinvolveslotsofmachines.Themaintechnologicalprocessesareshownasfollows:inspectionofforgingstock→boringthecenterholes→turningbearingareaonCNClathebeforeoverlaywelding→overlayweldingthebearingarea→roughandfinishturningtherotorincluding:excircle,endface,T-typebladegroove,compensatinggrooveand tooth.Rollingthebearingarea→boringthecouplingholesontheendfaceofflange,balancingholeandotherholes,millingallT-typelastbladeinsertiongrooveandflangeteeth→millingtheChristmastreebladegroove→assemblyrotorwithblade→turningtheshroudringofmovablevane→dynamicbalancetestoftherotor→finalcheck.AccordingtothedesigncharacteristicsandthedifficultyoftheHTGRrotor,wecarriedoutaseriesofresearchesonrotorprocesstoensurethattheprocessingaccuracymeetsthedesignrequirementsofthedrawings.TheworkingaccuracyresearchoftheT-typerotorbladeTheT-typerotorbladegroovesincludeT-typeandDoubleT-typerotorgroove.OneofthedifficultiesintheT-typerotorbladegrooveprocessisthathowmeasuringtheworkingsurface.NowwetakeT-typerotorbladegrooveasexample(AsshowninFigure1).WhentheworkingsurfaceoftheT-typerotorbladegroove,becauseofitshighaccuracy,weusethesameprocessingwayasmachiningthebearingareawithonemoresemi-finishing.WhenmachiningthesurfaceofT-typerotorbladegroove,the Figure1T-typerotorbladegroovedashedareashouldbekeptuntiltheworkingsurfaceisfinishedtofacilitatethemeasurement.WeuseL-typetoolstoturningtheredundantmaterialarea.Becauseofthelongtool,narrowtoolholdersandthesmallsizeofthetoolblade,cutterrelievingoftoolsiseasytohappen.Toreducethecutterrelieving,wemachiningtherotorinpositiveandnegativefeedpathalternay.Atthesametime,wemachiningtherotorwithrepeatedlycuttingandeverycuttingoutputshouldbesmallerthan1/3ofthediameter.ItwillbehelpfulforthechipRollingthebearingareaofRollingdepressionisanon-cuttingmachiningprocess,rollingtoolcanbedividedintorollertype,balltypeanddisctype.Whenusingtherollertypeandballtyperollingtools,itcansmooththesurfacebyremovingmicroscopicnotches.Whenusingthedisctyperollingtools,residualcompressivestressesclosetothesurfacewithgreatpenetrationisintroduced.Thesurfaceofworkpiecemetalcomesoutsticityflowandfillinginthelow-lyingvalleysintheoriginalresidual.Sothesurfaceroughnessofproductisreduced.Becauseofsticdeformationonthesurfaceofworkpiecemetal,thesurfacemicrostructureiscoldhardenedandgrainsizedecreases.ItFormsakindofdensefibrousandresidualstresslayerandimprovesthehardnessandstrength,so,corrosion andcomplianceoftheworkpiecesurfaceisimproved[1][3].Nowthedisctyperollingtoolsaremainusedinbearingareaprocessofnuclearpowerandcombinedcycle turbineunit,andthesetypetoolsarealsograduallyappliedtootherturbineunit.ForthedesignrequirementsofHTGRrotorbearingarea,weprefertherotordisctyperollingtoolsastherollingprocesstorollbearingarea.WhenrollingHTGRrotorbearingarea,accordingtospecificationweadoptspecialrollingtools(shownasfigure2)andparameters.WetakemanyrollingtestsforHTGRrotortoensuretherollingeffect. Therollingprocessofrotorbearingareaisgenerallydividedintothreesteps.Thefirststepistoapproachthebearingareawithangleαusingrigidrollingtool,thengowithacertaindepthalongrollingdirection.Theendpositionshouldbebackwithangleα(shownasfigure3).Thesecondstepistoapproachthebearingareawithangleαusingelasticrollingtool,thengowithacertaindepthalongrollingdirection.Theendpositionshouldbebackwithangleα(shownasfigure4).Thethirdstepisthesamewaytothesecondstep.Accordingtotheexperiments,welearnedhowtoadjusttherollingparameterstocontrolthesizeofthebearingareaafterrollingandhaveaccumulatedalotofexperiencesandknowledgeofrolling. TheresearchesonmillingprecisionoftheChristmastreerotorbladegrooveThemillingprocessoftheChristmastreerotorbladegrooveisoneoftheProcesses.ShanghaiturbinenthasfiveIngersollinwardNCmillingmachineandfivehome-madeNCmillingmachines,allthemachinescanensurehighprecisionindexingandmilling.WehavedecadesofexperienceinChristmastreerotorbladegroovemilling.TheChristmastreerotorbladegroovehascomplicatedstructure,highprecisionrequirements,figure5isside-entryroot.Thegeneralmillingtoolsmeettheprocess,andprofiledgroovingtoolsisthebestchoice.Inordertocontrolprecisionwhenmillingtheroot,wetakethefollowingmeasures:thefirstispreparingaworkinstructionofthequalitycontrolformillingoftheChristmastreerotorbladegroove,regulateandcontrolthemachineoperation;thesecond,layoutthelineofthegroovedepthonthesideofeverygroovetocontrolandcheckthedepthofthegroove;thethird,givethegrooveprofile,rightorleft,indexing,designandmakespecialcuttingtoolsandgauges,thecontrollingprecisiontempletandmakethegroovedepthinspectionproceduretocheckandcontrolthegroovedepthinsemi-finishingandfinishing;,beforethemilling,simulatethearcgrooveandstraightgroovetoensurethecorrectnessofprogram.Inmillingprocessoftheturbinerotor,shanghaiturbinentisdeveloarotormillingtoolconditionon-linemonitoringsystem,andhasdevelopedamillingtoolconditionmonitoringsystembasedoncuttingtemperature,cuttingsoundandcuttingpower.Itgainedthetool’scuttingtemperature,cuttingsoundandcuttingpowersignalunderdifferentwearconditionthroughexperimentsandtheysisofthesignal,preliminaryimplementationontooldamageidentification.Accordingtoourtests,wedeterminedthethresholdofthemonitoringparameteraboveanddesignedthemillingtoolconditionon-linemonitoringsystem.TherollingprecisionstudyoftheworkingsurfacecornersChristmastreerotorbladeTherollingprocessfortheworkingsurfacecornersofChristmastreerotorbladegrooveisoneoftechnologydifficultpoints.Wehavemadealotofprocessingtestsbeforemachiningtheproduct,includingtheprincipleofrollingtoolsandtheusingwayofrollingtools.WeknewthathowtoadjusttherollingtoolstocontrolthefinaldimensionsofChristmastreerotorbladegrooveandmadesuretheproductprecisionisthesametothedrawings.InordertocontrolthetechnologicalprocessofChristmastreerotorbladegrooveandmeetthequalityofthebladegroove,therollingoperationspecificationhasbeenmade.Themainrollingprocessoftheworkingsurfacecornersofrotorbladegrooveisdescribedasbelow:OpenthepumpandadjustthepressuretotherequirednumericalUsetherulertoadjusttheheightoftherollersaccordingtotheMeasuringandadjusting2or3pointseccentricityvalveaccordingtotheprogram。InstallingtherollingtooltothespindleandrollingtheworkingsurfacecornersrotorbladeLeavetherotorbladegroovebyClosingthepumpanddisassemblingtherollingFigure6rollingtoolsofworkpieceThemachiningwayofT-typelastbladeinsertionMostofT-typelastbladeinsertiongroovesaredesignedasparallelogramstyle.UsuallyT-typelastbladeinsertiongrooveofeachstageisdifferentfromothers,itisdeterminedbyαspecification(seefigure7).T-typelastbladeinsertiongroovesweremachinedontheboringmachine.Wemadeprogramby840Dprogramfunction.MostdimensionsofT-typelastbladeinsertiongroovesweredeterminedbyparametersandfourcornersofparallelogramwereformulatedbydeterminedparameter.Thenwemodularizetheprogramstructureeasily.Thisprogramiseasytoreadandwidelyapplied.Thetooldiameter,T-typegroovestage,T-typegroovedepth,allowanceandeverycuttingdepthareshowedbyparameter.TheoperatoronlymodifiestheT-typegroovestage,allowanceandev