机械类外文文献翻译中英文翻译抛丸清理机对板材轧辊进行抛丸处理Word格式.docx

机械类外文文献翻译中英文翻译抛丸清理机对板材轧辊进行抛丸处理Word格式.docx

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V.I.Meleshko,A.P.Kachailov,V.G.Boikov,

V.L.Mazur,T.P,KobkaandI.I.Krivolapov

Atthepresenttime~muchattentionisbeingdevotedtoincreasingthequalityofrolledproducts,partieularlysheet.Toasignificantdegreethisdependsuponthepreparationoftherollsurface.Manyplantsareengagedinimprovingthequalityofworkingtherollsurfaceinpreparingthemforrolling.ThisarticlewaswrittenbypersonnelfromZaporozhstalPlant,MagnetogorskMetallurgicalCombine,theInstituteforFerrousMetallurgy,Dnepropetrovsk,andMagnetogorskMiningandMetallurgicalInstituteonthisveryrealproblem..

Thesurfacemicrorelief,orroughness,ofcoldrolledconstructionalsheethasaninfluenceonthemechanicalandproductionpropertiesofmetal,andalsoonthefinishqualityofpartsmadefromthissheet.Thefinalsurfacemicroreliefofthinsheetsteelisformedinaskinpassonworkroilswhichhavebeengivenaroughfinishwithmetalshot.

Normallytheroughsurfacefinishontheworkrollsofskinpassstandsisproducedinpneumaticandrotorshotblastingmachines.Experienceintheirusehasshownthatthepneumaticmachinesusedinthecountry'

ssteelplantsdonotfilltheneedforhighqualityblastingofrollsurfaces.

In1969theInstituteforFerrousMetallurgy,Dnepropetrovsk,didworkontheSM-2shotblastingmachineinNo.1ColdRoilingMillofZaprozhstalPlant,whichrevealedanumberofshortcomingsinitsconstruction.

ToprovidesheetwiththesurfaceroughnessrequiredbythespecificationsofVolgaAutomobilePlant（Ra=0.8-1.6g）,thebasicrequirementsforthedesignofshotblastingmachinesweredetermined,Themachinemustprovide:

1.aconstantshotsizeduringoperation,inotherwords,effectiveremovalofshotofthespecifiedsizefrom

wornshot;

2.thepossibilityofcontrollingairpressureinthecollectoroftheshotblastmachineduringstableoperations;

3.thehandlingofworkrollsofdifferentdiameters（400-500mm）withoutspecialequipmentonthemachine;

;

4.simplicityincontrolandconvenienceinmaintenance.

Fig.1

TheSM-2machine（Fig.1）consistsofastationaryclosedchamber!

withatrolleyonwheelsaadmovab!

enozzles2~whichundertheactionofcompressedairdischargeshotontotherollsurface,awormconveyor8,anelevatorwithaseparator4,theshotblastequipment5,andanexhaustsystem6.Theequipmentismountedonaspecialfoundation1905mmbelowthefloorlevelThelengthofthemachinewiththetrolleyoutis15fl00ram,theheight4070ram,andthewidth4600mr~Thedimensionsoftherollshandledare400-500mmindiameterand2000-4000mminlength.Thetotalweightoftheequipmentis15tons.

Asresearchhasshown,thedynamicsofthewearofaworkingmixtureofabrasiveandtheoriginalconditionoftheshotchangesduringoperation.Duringblasting,theshottakesonawidersizerangeandisworndown,formingmanyfineparticles.Theconditionsunderwhichthepartsareblasteddependuponthesizeoftheshotused.Thecontaminationofthespecifiedsizebyfineparticlesdisruptstheprocess,producingapoorqualitysurfaceontherollsandconsequentlyonthesheet.Toeliminatetheseproblemsitisnecessarytoeitherregularlymeasurethecompositionoftheshotandmakeappropriatechangesintheblastingsequence,whichisdifficulttodoinpractice,ortoscreentheshotduringoperationofthemachinetoprovidethespecifiedparticlesize.

Stabilityintheblastingprocessisalsodeterminedbythequantityofshotdeliveredtothenozzles.Itwasexperimentallyestablishedthatsupplying0.3-0.4kg/secofshottothetwonozzlesinoperatingwithanairpressureof2.5-4.0atmprovidedstableoperation.Equippingthemachinewithscreeningdevicesisaneffectivemethodformaintainingaconstantshotsizemix.ThisisconfirmedbothbydataintheliteratureandbyexperienceintheoperationofSM-1andTsKb_P-1shotblastmachinesatZaporozhstalPlant.

Theshotisdeliveredtothesurfaceoftherollbytheshotblastequipment,thechamberofwhichisdividedbytwodiaphragmswithchargingventsintothreecompartmentsandisequippedwithanelectropneumaticcontroldevice.Theworkingmixturefromtheuppercompartmentofthechamberdropstothelowerandthentothecollector.Duringoperationofthemachine,theventsareclosed（turnedon）.Theshotispouredineitherafterturningoffthevalvesbytheelectropneumaticcontroldevice,oraftershuttingdownthemachinebytheoperator.Whenitisturnedoff,theventdescends,andbetweenitandthediaphragmacirculargap5mmwideisformed.Theventisaconewithaslopeofabout30%Theshotdropsslowlythroughthisgapbutnotcompletely,andthereforeitincreasestot0ram.Theloadingventsarealternatelyturnedonbythecontroldevice.ThefirsttimetheSM-2machinewasrepaired,itwasdiscoveredthatthecontroldevicefrequentlydidnotoperatebecauseofcorrosionoftheparts.Withnormalchargingofabrasive（375kgaccordingtothenameplate）,blastingmustbestoppedaftereachalternatepassofthenozzles,sinceafteranotherpasstheshotinthelowercompartmentisinsufficient,andduringblasting,Withnonoperationofthecontroldevice,itdoesnotdropfromtheuppercompartmenttothelower.Deliveryofthenextportionofshotmustbedoneonlyaftertheoperatordisconnectstheshotblastequipmentfromtheairsystem.Inthiscasebothchargingventsareopened,andtheabrasiveisfedtothelowercompartment.Continuousoperationofthemachineforthreeorfourpassesofthenozzleswithnonoperationofthecontroldeviceandthedeliveryofshotdescribedabovebecamepossibleafterincreasingthestandardchargeto650kg.However,thebasicsolutionofthisproblemisstableoperationofthecontroldevice.

Theusedshotiscollectedbythecollectingbunkeroftheworkingchamberanddropsintothereceivingchuteofthewormconveyor.Theplatesparalleltothewormconveyorareatagreaterangle,andthoseperpendicularareatlessofanangle,whichtendstocollectshotonthem.Therefore,afterblastingonerollitisnecessarytoshutthemachinedowntopushtheaccumulatedshotontothescrewconveyor.Toeliminatethisshortcoming,itispossibletolengthenthescrewconveyor,whichishalfthelengthoftheworkingchamber.Inaddition,thesmallerplateisremovedcompletely,andtheparallelplatesareelongatedtocorrespondwiththelengthofthewormconveyor.

Thecompressedairsuppliedtothecollectoroftheshotblastequipmentisdriedbyanoilmoistureseparator.However,thismethodofdryingisinadequate.Watervaporcondensesinthemainlineandintheshotblastequipment,andasaresultshotstickstogetherinthelowercompartmentandformsasolidmass.Thesolidmassclogstheverticalchannelsalongwhichtheabrasiveistransportedtothecollectoranddisruptstheoptimumratioofshottoairintheblast.Thishasadetrimentaleffectontheblastingprocessandthequalityoftherollsurface.Thepresenceofmoistureintheaircausescorrosionoftheequipmentandcausesoperationofthepneumaticequipmentofthemachinetobepoorer.Therefore,indesigningshotblastequipment,itisnecessarytospecifyequipmentfordryingtheair.Foreignfirms,forexample,usespecialdryingequipmentutilizingwaterabsorbingsubstancessuchassilicagelandactivatedaluminafordryingcompressedair.

Themechanismformovingthenozzlehasanumberofshortcomings.Applicationofthejetofabrasivematerialontotherollisthroughanozzlemountedinanelbowshapedgun（Fig.2）.Ashortcomingofthegunisthethrottlingofthemixtureofcompressedairandshotwheretheverticalandhorizontalchannelsjoin.Thejunctionisarightangle,whichcausesquickwearingawayoftheelbow.Thecrosssectionsofthechannelsandnozzlewasincreased.However,withanincreaseinthenozzlediameterfrom10to12mm（theallowablemaximum）theconsumption

ofairincreasedfrom13to19mS/h,whichchangedtheratioofshottoairintheblast.However,thisratiomustbekeptconstant.Sinceduringblastingitisdifficulttomakecorrections,itwasnecessary~oimprovethedesignandincreasethewearresistanceoftheparts.

Fig.2

Forthispurposeanewdesignofblastguns,inwhichthediameterofthechannelswasincreased（Fig.2b）andtheshapeofthetransitionfromthechanneltothechannelandnozzlewaschanged,wasproposedandtested,Thenewnozzledesignismuchmoreeffective.Afterfivemonthsofoperation,noticeablesignsofwearintheelbowandnozzlehavenotbeenfound,whiletheolddesignelbowsworeoutinamonth.

Theblastgunsaremovedalongtherollbyaconveyorbelt.UndertheactionoftheweightofthetroJ.leyandoscillationscausedbyitsmovementalongtheguidesonwhichshotfallingfromthesurfaceoftherollsaccumulates,thebeltgetsoutofalignment.Asaresult,theimpactofthestreamofshotonthesurfaceisnotatarightangle,butglancing,whichproducesapoorersurfacequality.Placingastripundertheguneliminatedthisproblem,andtherollsurfacequalitybecamesatisfactory.

InthefirstperiodofoperationthecompressedairtntheSM-2machinewasobtainedfromtheshopmaini'

ine,whichhasapressureof6atm.Accordingtoreadingsonamanometerplacedbeforethecollectoroftheshotbtaatunit,theairpressureinitdidnotexceed4.0aim.Withthispressure,evenwiththeuseofthefinestshot（DChK-0.8）,theroughnessoftherollsisattheupperlimit（Ra=2.7#）.

Therefore,itwasnecessarytoreducetheworkingpressureoftheair.Anairvalv