带式输送机的发展外文翻译中英文翻译外文文献翻译.docx
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带式输送机的发展外文翻译中英文翻译外文文献翻译.docx
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带式输送机的发展外文翻译中英文翻译外文文献翻译
附录1
DEVELOPMENTOFTHECABLEBELTCONVEYOR
lanMainThomsonBSc(Eng.)
ManagingDirector
CableBeltLtd
Summary
TheearlydevelopmentofbeltConveyingisdiscussedshowinghowtheCablebeltsystemdevelopedfromthesamerequirements.Thevariousdesignconceptsarecomparedwiththoseofthetroughedbeltconveyorhighlightingtheareasofadvantageanddisadvantage.
TheareasofconveyingwheretheCableBeltsystemismostusefulandthelikelydevelopmentsareoutlined.Theseandotherdevelopmentshaveledtomanymajorconveyorinstallationsincludinga2flight52kmsystembeingconstructedtotheCableBeltdesign.
DevelopmentoftheCableBeltConveyor
Theoriginofthebeltconveyorisnoteasytoclearlyidentifybuttherearereferencestosimpleformsasearlyas1795.Howeveritwasnotuntilthedramaticincreaseintheworldtradingofgrainafter1850thatmajorimprovementsweremade¹.
Thefirstformofconveyorwasaflatbeltrunninginatroughwhichwasquicklyimprovedbytheintroductionofstraightidlerstoreplaceslidingfrictionbyrollingfriction.Theneedtoincreasethecapacityandcentralisethematerialloadledtotheappearanceatthesametimeofbothofthemostcommonformsofheavydutybeltconveyors,thetroughedbeltconveyorandtheCableBeltconveyor.
Inthelate1860'stheuseintroughedbeltconveyorsofstraightrollerswithconicalordishedendswasobsoleteuntiltheearly1890's.Theintroductionin1865ofinclinedstraight'concentrator'idlersledtotheconveyorintheThomasRobinsJnr.patentof1896,whichisregardedasthefirsttroughedbeltconveyor.Sincethatdatewhilsttherehavebeenmanyimportantimprovementsinthedetailoftheidler,beltanddriveconstruction,thebasicconceptofthetroughedbeltconveyoristhesameasoutlinedintheworkcompletedintheearly1900's.
TheCableBeltconveyorprinciplewhilstofearlieroriginwasnotdevelopedinatrulysuccessfulformuntil1952.
Oneoftheearliestformswasthatdevelopedin1859andshowninthesketchfig.1.Thisconsistedoftwoparallelendlessleatherorrubberbeltstowhichwereattachedatintervalscurvedmeta1spreaderssupportingacanvastrough.Thereweremanyothersimilarconveyorsbuttheyallsufferedfromthesamebasicdefectthatthecarryingbeltwasrigidlyattachedtothedrivingbelts.Thisledtothedisadvantagesthatthedrivebeltsdonotstretchalikeandthatthespreaderbarsarestressedandeventuallybreakfreefromthedrivebelts.
TheCableBeltsystemsuccessfullyovercamethesedefectsandsinceitsintroductionhasgenerallybeenacceptedintheconveyorfieldforLongdistanceapplications.Asubstantialproportionofthesingleflightconveyorsover5kmlongthathavebeeninstalledarenowoftheCableBeltdesign.
ThefundamentaldesigndifferencesmadeintheCableBeltsystemweretousearounddrivebeltintheformofawirerope,andnottoattachthecarryingbelttothedrivebelts.Thefirstofthesechangeswasaimedatgettingoverthedifficultyoftrainingtoruninparallelapairofflatbeltsbysubstitutingpositivelylocatedroundcablesrunningingroovedpulleys.
EarlyBeltConveyorFig1
ThesecondchangewasthepointthatallowedtheCableBeltsystemtooperatesuccessfullyincontrasttotheotherearlierattempts.Thecarryingbeltmerelyrestsonthedrivecables,thesecablessittingwithinshoeswhicharemouldedonthebe1tsurfaces.ItmayseemthatdependingonfrictionalonetheCableBeltisliabletohavethebeltslipbackwardsonthedrivecables.Howeverasallbeltconveyorsdependonfrictionbetweenthebeltandthematerialcarriedtoallowthemtooperateatall,theonlyrequirementisthatthefrictionbetweenthebeltandthedrivecablesshouldbegreaterthanbetweenthebeltandthematerial.Thiswasachievedbyshapingthebeltshoestogripthedrivecables.
IthasbeenpossibleusingCableBeltbeltingwithspeciallyformedsurfacestorunonslopeconveyorsystemswheretheoverallgradeis21°andwithparticularsectionsof28°,withoutexperiencingslippingofthebeltonthedrivecables.
WhilsttheCableBeltconveyorwasdevelopedatatimewhenthepowersavailableofupto300kWwereregardedasoutstandingthebasicconceptisstillretainedevenwhennow,singleconveyorsof30000metrelengthand8000kWpowerarebeingbuilt.
Theterminalunitsaresimilartothoseinaconventionaltroughedconveyorexceptthattheyalsoservetoseparateandrejointhecarryingbeltanddrivecables.Atypicalexampleofaheaddischargeunitisshowninfig.6.
Obviouslytheterminalsotherthanthedriveunitaremorecomplexthaninaconventionaltroughedconveyorandtakeupmorespaceparticularlyinthecaseofthetensioningarrangements.ThisisnottrueofthedriveasforacomparablepowerratingitiscompactandhastheadvantagethatitcanbelocatedremotefromtheCableBeltconveyorbeltline.
HeadDischargeUnitFig6
Asthemodulusofelasticityofthedrivecablesiskeptrelativelylowinordertoallowtheuseofverylowstartingtorquesandeachdrivecableistensioned,thetensionsystemdoesrequiresubstantialtake-upspaceandismorecomplexasisillustratedinfig.7.
TypicalTensioningArrangementFig7
TheconceptsbehindthedesignoftheCableBeltconveyorareverysimilartoaconventionalconveyorinthatthereisconveyorfrictionandtheverticalalignmentisaseriesofcatenariesbutofcoursethefactorsusedvaryconsiderablybecauseofthedifferentcharacteristics.
Theconveyorfrictionlossesareconsiderablyreducedprincipallybecauseofthesignificantlylowernumberandweightofmovingpartsinacomparablesystem.
Thisreductionisnormallyintheorderof30%.Inadditionthefrictionlossesduetotheworkingofbeltandmaterialastheypassovertheidlersaresignificantlyless.ithasbeendeterminedempiricallythatthereisintheorderofa10%reductioninthefrictionlosses.
Theestablishingofthefacts,evenonacomparativebasis,withregardtoconveyorfrictionhasproveddifficultasallthedataisempiricalandthevariousdesignstandardscanshowmarkedlydifferentresults.Inadditionconveyorfrictionwillvarywithtemperature,ageandstandardsofinstallationandmaintenance.Howeverinarecentmajorinstallationithasbeenpossibletocomparethefrictionvalues,atleastonadesignbasisandascanbeseenbelowthesebearoutthedifferences.
Conventional
CableBelt
NumberofRotatingParts
100
76
WeightofMovingParts
100
64
FrictionLosses
100
67
IndeterminingtheverticalalignmentoftheCableBeltsystemwhilsttheformulaeandcalculationarethesame,greatcaremustbeexercisedasitisnotpossibletoallow'liftoff'incatenariestooccur.
EarlyCableBeltBeltingFig2
IntermediateCableBeltBeltingFig3
ModernCableBeltBeltingFig4
TheCableBeltisbestdefinedasabeltconveyorwithalaterallyrigidbutlongitudinallyflexiblecarryingbeltwhichissupportedatornearitsedgesontwoparallelendlessloomsofdrivecable,thesecablesinturnbeingsupportedatintervalsbygroovedpul1eys.Theintegralreductiongearanddriveunitdrivesbothdrivecab1esandincorporatesadifferentialtoequalisetensionsinthecables.Inadditioneachofthedrivecablecircuitsisseparatelytensionedtoallowforthedifferentialstretchoftheseduringoperation.
TheuniquefeatureoftheCableBeltsystemisthebelt.Originallythiswasafabricreinforcedrubberbeltwhichhadmouldedintoitspringsteelstrapsat450mmintervals.Thesestrapsprotrudedbeyondtheedgesofthebellasillustratedinfig.2,andhadmechanicallyattachedtothemametalshoewithrubberLiningwhereitgrippedthedrivecable.Thiswassupersededbyaonepiecemouldedconstructionshowninfig.3wheresmallercrosssectionstrapsatintervalsof100mmweremouldedentirelywithinthebeltandtheshoestogripthedrivecableswerecontinuousmouldingsalongtheedgeofthebelt.
Typical4PulleyLineStandFig5
Recentlyafurtherchangewasmade,illustratedinfig.4wherebytheshoeswhichgripthedrivecableonthematerialcarryingrunhavebeenmovedinwards.Thisincreasesthestabilityofthebeltwhensubjectedtooverloadingandinadditionallowstheuseofsmallercrosssectionstraps.
AngleStationFig8
Itisnormalthatonatypicallongcentreconveyortheeventualreplacementofthebeltisnotforreasonsofabrasionofthesurfaceormechanicaldamage,butduetothevariousageingprocessesthataffectrubbercompoundssuchasheat,sunlight,andozone.Asaresultithasbeennecessarytodevelopspecialsyntheticrubbercompoundsthatareinherentlyresistanttoageing.
ThespecificationofthedrivecableswhilstsimilarsuperficiallytoanormalwireropearespeciallymadetoaCableBeltspecificationwithdesigncriterialaiddownforindividualwiresize,fatiguelifeandinternallubrication.Theyareofgalvanisedconstruction,Lang'sLaywitheitherafibreorwireropecore.Currentlytheyareusedinsizesupto60mmdiameterandbreakingloadsof260tonnes.AsthisisthetensionreinforcingmemberoftheCableBeltsystemgreatattentionispaidtoreducingthenumberofsplicesanddrivecablesofupto100tonnesweightforeachsectionhavebeenused.
Alongthelineoftheconveyoritissupportedatintervalsofbetween5and10metresbygroovedpulleysapproximately300mmindiameter.Previouslythesepulleyswereofahardenedsteelconstructionbutthecurrentdesignisforapulleywithareplacementrubberlinedtread.Thesepulleysaremountedinpairsonarticulatedarmswhichallowtheconveyortoselfal
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