带式输送机外文翻译---煤矿输送带软启动机制的比较.docx

带式输送机外文翻译---煤矿输送带软启动机制的比较.docx

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英文文献

AComparisonofSoftStartMechanismsforMiningBeltConveyors

MichaelL.Nave,P.E.

CONSOLInc.

1800WashingtonRoadPittsburgh,PA15241

BeltConveyorsareanimportantmethodfortransportationofbulkmaterialsintheminingindustry.Thecontroloftheapplicationofthestartingtorquefromthebeltdrivesystemtothebeltfabricaffectstheperformance,lifecost,andreliabilityoftheconveyor.Thispaperexaminesapplicationsofeachstartingmethodwithinthecoalminingindustry.

INTRODUCTION

Thedrivepulleyviafrictionbetweenthedrivepulleyandthebeltfabricmusttransmittheforcerequiredtomoveabeltconveyor.Inordertotransmitpowertheremustbeadifferenceinthebelttensionasitapproachesandleavesthedrivepulley.Theseconditionsaretrueforsteadystaterunning,starting,andstopping.Traditionally,beltdesignsarebasedonstaticcalculationsofrunningforces.Sincestartingandstoppingarenotexaminedindetail,safetyfactorsareappliedtostaticloadings（Harrison,1987）.Thispaperwillprimarilyaddressthestartingoraccelerationdutyoftheconveyor.Thebeltdesignermustcontrolstartingaccelerationtopreventexcessivetensioninthebeltfabricandforcesinthebeltdrivesystem（Surtees,1986）.Highaccelerationforcescanadverselyaffectthebeltfabric,beltsplices,drivepulleys,idlerpulleys,shafts,bearings,speedreducers,andcouplings.Uncontrolledaccelerationforcescancausebeltconveyorsystemperformanceproblemswithverticalcurves,excessivebelttake-upmovement,lossofdrivepulleyfriction,spillageofmaterials,andfestooningofthebeltfabric.ThebeltdesignerIsconfrontedwithtwoproblems,Thebeltdrivesystemmustproduceaminimumtorquepowerfulenoughtostarttheconveyor,andcontrolledsuchthattheaccelerationforcesarewithinsafelimits.Smoothstartingoftheconveyorcanbeaccomplishedbytheuseofdrivetorquecontrolequipment,eithermechanicalorelectrical,oracombinationofthetwo（CEM,1979）.

SOFTSTARTMECHANISMEVALUATIONCRITERION

Whatisthebestbeltconveyordrivesystem?

Theanswerdependsonmanyvariables.Thebestsystemisonethatprovidesacceptablecontrolforstarting,running,andstoppingatareasonablecostandwithhighreliability（LlewellynandSudarshan,1978）.

BeltDriveSystem

Forthepurposesofthispaperwewillassumethatbeltconveyorsarealmostalwaysdrivenbyelectricalprimemovers（GoodyearTireandRubber,1982）.Thebelt"drivesystem"shallconsistofmultiplecomponentsincludingtheelectricalprimemover,theelectricalmotorstarterwithcontrolsystem,themotorcoupling,thespeedreducer,thelowspeedcoupling,thebeltdrivepulley,andthepulleybrakeorholdback（Zur,1986）.Itisimportantthatthebeltdesignerexaminetheapplicabilityofeachsystemcomponenttotheparticularapplication.Forthepurposeofthispaper,wewillassumethatalldrivesystemcomponentsarelocatedinthefreshair,non-permissible,areasofthemine,orinnon-hazardous,NationalElectricalCode,Article500explosion-proof,areasofthesurfaceofthemine.

BeltDriveComponentAttributes

Size.

Certaindrivecomponentsareavailableandpracticalindifferentsizeranges.Forthisdiscussion,wewillassumethatbeltdrivesystemsrangefromfractionalhorsepowertomultiplesofthousandsofhorsepower.Smalldrivesystemsareoftenbelow50horsepower.Mediumsystemsrangefrom50to1000horsepower.Largesystemscanbeconsideredabove1000horsepower.Divisionofsizesintothesegroupsisentirelyarbitrary.Caremustbetakentoresistthetemptationtoovermotororundermotorabeltflighttoenhancestandardization.Anovermotoreddriveresultsinpoorefficiencyandthepotentialforhightorques,whileanundermotoreddrivecouldresultindestructiveoverspeedingonregeneration,oroverheatingwithshortenedmotorlife（Lodi,etal.,1978）.

TorqueControl.

Beltdesignerstrytolimitthestartingtorquetonomorethan150%oftherunningtorque（Cema,1979;Goodyear,1982）.Thelimitontheappliedstartingtorqueisoftenthelimitofratingofthebeltcarcass,beltsplice,pulleylagging,orshaftdeflections.Onlargerbeltsandbeltswithoptimizedsizedcomponents,torquelimitsof110%through125%arecommon（Elberton,1986）.Inadditiontoatorquelimit,thebeltstartermayberequiredtolimittorqueincrementsthatwouldstretchbeltingandcausetravelingwaves.Anidealstartingcontrolsystemwouldapplyapretensiontorquetothebeltatrestuptothepointofbreakaway,ormovementoftheentirebelt,thenatorqueequaltothemovementrequirementsofthebeltwithloadplusaconstanttorquetoacceleratetheinertiaofthesystemcomponentsfromresttofinalrunningspeed.Thiswouldminimizesystemtransientforcesandbeltstretch（Shultz,1992）.Differentdrivesystemsexhibitvaryi