高速带式输送机的设计-外文翻译

附件AesignofHighSpeedBeltConveyorsG.Lodewijks,TheNetherlands.SUMMARYThispaperdiscussesaspectsofhigh-speedbeltconveyordesign.Thecapacityofabeltconveyorisdeterminedbythebeltspeedgivenabeltwidthandtroughingangle.Beltspeedselectionhoweverislimitedbypracticalconsiderations,whicharediscussedinthispaper.Thebeltspeedalsoaffectstheperformanceoftheconveyorbelt,asforexampleitsenergyconsumptionandthestabilityofit'srunningbehavior.Amethodisdiscussedtoevaluatetheenergyconsumptionofconveyorbeltsbyusingthelossfactoroftransport.Withvariationofthebeltspeedthesafetyfactorrequirementsvary,whichwillaffecttherequiredbeltstrength.Anewmethodtoaccountfortheeffectofthebeltspeedonthesafetyfactorispresented.Finally,theimpactofthebeltspeedoncomponentselectionandonthedesignoftransferstationsisdiscussed.1INTRODUCTIONPastresearchhasshowntheeconomicalfeasibilityofusingnarrower,fasterrunningconveyorbeltsversuswider,slowerrunningbeltsforlongoverlandbeltconveyorsystems.Seeforexample[I]-[5].Today,conveyorbeltsrunningatspeedsaround8m/sarenoexceptions.However,velocitiesover10m/supto20m/saretechnically(dynamically)feasibleandmayalsobeeconomicallyfeasible.Inthispaperbeltspeedsbetweenthe10and20m/sareclassifiedashigh.Beltspeedsbelowthe10m/sareclassifiedaslow.Usinghighbeltspeedsshouldneverbeagoalinitself.Ifusinghighbeltspeedsisnoteconomicallybeneficialorifasafeandreliableoperationisnotensuredatahighbeltspeedthenalowerbeltspeedshouldbeselected.Selectionofthebeltspeedispartofthetotaldesignprocess.Theoptimumbeltconveyordesignisdeterminedbystaticorsteadystatedesignmethods.Inthesemethodsthebeltisassumedtobearigid,inelasticbody.Thisenablesquantificationofthesteady-stateoperationofthebeltconveyoranddeterminationofthesizeofconveyorcomponents.Thespecificationofthesteady-stateoperationincludesaquantificationofthesteady-staterunningbelttensionsandpowerconsumptionforallmaterialloadingandrelevantambientconditions.Itshouldberealizedthatfindingtheoptimumdesignisnotaone-timeeffortbutaniterativeprocess[6].Designfine-tuning,determinationoftheoptimumstartingandstoppingprocedures,includingdeterminationoftherequiredcontrolalgorithms,anddeterminationofthesettingsandsizesofconveyorcomponentssuchasdrives,brakesandflywheels,aredeterminedbydynamicdesignmethods.Inthesedesignmethods,alsoreferredtoasdynamicanalyses,thebeltisassumedtobeathree-dimensional(visco-)elasticbody.Athreedimensionalwavetheoryshouldbeusedtostudytimedependenttransmissionoflargelocalforceanddisplacementdisturbancesalongthebelt[7].Inthistheorythebeltisdividedintoaseriesoffiniteelements.Thefiniteelementsincorporate(visco-)elasticspringsandmasses.Theconstitutivecharacteristicsofthefiniteelementsmustrepresenttherheologicalcharacteristicsofthebelt.Dynamicanalysisproducesthebelttensionandpowerconsumptionduringnon-stationaryoperation,likestartingandstopping,ofthebeltconveyor.Thispaperdiscussesthedesignofhighbelt-speedconveyors,inparticulartheimpactofusinghighbeltspeedsontheperformanceoftheconveyorbeltintermsofenergyconsumptionandsafetyfactorrequirements.Usinghighbeltspeedsalsorequireshighreliabilityofconveyorcomponentssuchasidlerstoachieveanacceptablecomponentlife.Anotherimportantaspectofhigh-speedbeltconveyordesignisthedesignofefficientfeedinganddischargearrangements.Theseaspectswillbediscussedbriefly.2BELTSPEED2.1BELTSPEEDSELECTIONThelowestoverallbeltconveyorcostoccurintherangeofbeltwidthsof0.6to1.0m[2].Therequiredconveyingcapacitycanbereachedbyselectionofabeltwidthinthisrangeandselectingwhateverbeltspeedisrequiredtoachievetherequiredflowrate.Figure1showsanexampleofcombinationsofbeltspeedandbeltwidthtoachieveSpecificconveyorcapacities.Inthisexampleitisassumedthatthebulkdensityis850kg/m3(coal)andthatthetroughangleandthesurchargeangleare35'and20'respectively.Figure1:Beltwidthversusbeltspeedfordifferentcapacities.Beltspeedselectionishoweverlimitedbypracticalconsiderations.Afirstaspectisthetroughabilityofthebelt.InFigure1thereisnorelationwiththerequiredbeltstrength(rating),whichpartlydependsontheconveyorlengthandelevation.Thecombinationofbeltwidthandstrengthmustbechosensuchthatgoodtroughabilityofthebeltisensured.Ifthetroughabilityisnotsufficientthenthebeltwillnottrackproperly.Thiswillresultinunstablerunningbehaviorofthebelt,inparticularathighbeltspeeds,whichisnotacceptable.Normally,beltmanufacturersexpectasufficientlystraightrunifapproximately40%ofthebeltwidthwhenrunningempty,makescontactwiththecarryingidlers.Approximately10%shouldmaketangentialcontactwiththecenteridlerroll.Asecondaspectisthespeedoftheairrelativetothespeedofthebulksolidmaterialonthebelt(relativeairspeed).Iftherelativeairspeedexceedscertainlimitsthendustwilldevelop.Thisisinparticularapotentialprobleminmineshaftswhereadownwardairflowismaintainedforventilationpurposes.Thelimitinrelativeairspeeddependsonambientconditionsandbulkmaterialcharacteristics.Athirdaspectisthenoisegeneratedbythebeltconveyorsystem.Noiselevelsgenerallyincreasewithincreasingbeltspeed.Inresidentialareasnoiselevelsarerestrictedtoforexample65dB.Althoughnoiselevelsaregreatlyaffectedbythed