管状带式输送机的参数计算和结构设计.docx

管状带式输送机的参数计算和结构设计.docx

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管状带式输送机的参数计算和结构设计

中文3150字

英文原文

ParametersCalculationandStructureDesignofPipeBeltConveyer

ZaimeiZhang1,FangZhou2,JianhengJi2

1SchoolofMechanicalEngineering,UniversityofJinan,Jinan250022,ShandongProvince,China

2DepartmentsofInformationEngineering,ShandongWaterVocationalCollege,Rizhao276826,ShandongProvince,China

Abstract:

Pipebeltconveyorisanewtypeofspecialbeltconveyoranditiswildlyusedinconveyingpowdermaterial.Inthepaper,theadvantagesofpipebeltconveyorareintroduced.Calculationofpipebeltconveyorsmainparametersisdifferentfromthatofconventionalbeltconveyors.Theparameterssuchasthroughput,beltspeed,beltwidth,resistance,tensioninbeltandpoweraredescribed.Thelengthoftransition

sectionisanalyzedbecauseitisimportanttothebeltlife.Hexagonsupportingrollersandtippingdevicearenecessarypartsofpipebeltconveyor.Thestructuresofthemarealsodiscussed.

keywords:

PipeBeltConveyor,TransitionSection,HexagonSupportingRollers,TippingDevice

1.Introduction

Pipebeltconveyorisanewtypeofspecialbeltconveyorwhichdevelopedfromtheconventionalbeltconveyor.Inthisconveyor,flatbeltisforcedtobetubularbysupportingrollergroupsandmaterialconveyedisenvelopedinit.Thereforeairproofconveyisrealizedinwholeconveyanceline.Pipebeltconveyorwasproposedin1964byJapanPipeConveyor（JPC）,anditwentintorealusein1979[1].Afterthat,itwasrapidlydevelopedinGennanyandAmericaandwidelyusedabroad.Butitisnotdeeplystudiedandits'useismuchlimitedinChina.

2.Thecharacteristicsofpipebeltconveyor

Figurelisforthestructureofpipebeltconveyor.Theloadisputtedonbythefeederattheendofconveyor.

Thebeltisflatwhenitrunsthroughthedrivenrolleranditisconductedbyaseriesofsupportingrollerstobetubulargradually.Thusairproofconveyanceisrealized.Inordertodischarge,thepipeisalsoconductedbyaseriesofsupportingrollerstobeflatnearthedrivingroller.Theconveyordischargesatitshead.Two-wayconveyancecanberealized.Buttippingdeviceforbeltmustbeadded.Characteristicsareobviousduetoitsspecialstructurecomparingwithotherbeltconveyor[1].

（1）Unpollutedconveyance

Inpipebeltconveyor,materialdoesn'tcomeoutandisn'tinfluencedbyenvironmentbecausethebeltistubularandthetwosideslapovereachother.Whenitconveyspowder,foodandchemicalmaterialetc.,thisadvantageisobvious.

（2）Bigobliquityofconveyance

Obliquitycanreachabout18intheconventionalbeltconveyor.Butinpipebeltconveyor,materialisenvelopedinpipeandfrictionbetweenmaterialandbeltisgreaterthanbefore.Soobliquitycanbeincreasedto30Thebiggerobliquityis,theshorterconveyancelengthwillbe.Thiscanresultinlowercost.

（3）Two-wayconveyanceisconvenient

Beltcanbetubularinreturnofpipebeltconveyorandmaterialcanbeconveyedinthereversedirectionbyspecialdevicesuchasspecialfeederandtippingdevice.

（4）Conveyorbedisnarrow

Inconveyance,bedisnarrowbecausethecrosssectionisacircle.Therequiredbuildingspaceandbuildingsteelarereduced.Thebedcostislowanditcanbeusedwhenspaceislimited.

3.Mainparameterscalculationofpipebeltconveyor

Mainparametersinpipebeltconveyorarethroughput,beltwidth,beltspeedandpower.Butproductionthroughputisalwaysgiven.

3.1Calculationthroughput

Throughputofconveyorcanbefonnulatedasfollows[2]:

Where

isbeltspeed,

isthepipearea,

isdensityofmaterialconveyedand

iscoefficientofmaterialfilling,

=0.44～0.8.Ifmaterialsizeislessthanonethirdofpipediameter,

=0.8.Ifmaterialsizeisonethirdofpipediameter,

=0.75.Ifmaterialsizeishalfofpipediameter,

=0.58.Ifmaterialsizeistwothirdsofpipediameter,

=0.44.

3.2Beltspeed

Beltspeedisdeterminedbycharacteristicofmaterial,throughput,beltwidthandtheinstallationmethodofconveyor.Generallyspeaking,quickbeltspeedisbeneficialbecauseitcanreducebeltwidthandtensioninbeltwhenthroughputisconstant.Thiswilleconomizeoninvestmentinbeltandpowerconsumption.Beltspeedusuallyusedis2～5m/s[3].

3.3Beltwidth

Beltwidthcanbecalculatedaccordingthroughput.Thebeltdiametercanbeexpressed[2]:

Wheredispipediameter.

Thelapoftwosidesisaboutonethirdorhalfofpipediameter.Whenbeltistubular,therelationshipbetweenbeltwidthandpipediameterisasfollow:

3.4Runningresistancecalculation

Themethodhasnodifferenceinresistancecalculationbetweenpipebeltconveyorandconventionalbeltconveyor.Generally,Coefficientofresistanceisusuallyusedinresistancecalculation.Tensioninbeltiscalculatedpointbypoint.Extrusionforceisincreasedbecausematerialisenvelopedinpipe.Thereforecoefficientofresistanceinpipebeltconveyorisgreaterthanthatinconventionalbeltconveyor.

（1）Resistanceintangent

Resistanceinbeltwithload[2]:

Resistanceinbeltwithoutload:

Where

isresistanceinrunning,

istheunitmassofbeltpermeter,

istheaverageunitmassoftheuppersupportingrollerspermeteralongthebelt,

istheunitmassofmaterialpermeteralongthebelt,

istheaverageunitmassofthebelowsupportingrollerspermeteralongthebelt,

isthelengthofconveyance,

isobliquityofconveyanceand

iscoefficientofresistanceinsupportingrollers,showedintable1.

Table1.Coefficientofresistanceinsupportingrollers

（2）Resistanceincurvature

Resistanceincurvatureiscausedbybeltossificationandfrictioninrollerbearings.Itisproportionaltothetensionatcurvatureentrance.Thatis[2]:

Where

isthetensioninbeltatcurvatureexit,

isthetensioninbeltatcurvatureentranceand

iscoefficientofresistance.

3.5Tensioncalculationinbelt

Afterresistanceineachsectionhasbeencalculated,wecancalculatethetensionateverypoint.Wecandividewholepathintoseveraltangentsandcurvaturesandnumbereveryjointbeforewecalculate.Tensionatanypointiscalculatedbytheformulaasfollowed[2]:

Where

and

aretensioninbeltatpoint

andpoint

isresistancebetweenpoint

andpoint

.

Thetensionatdrivingrollerentranceanddrivingrollerexitcanbeobtained.Circumferentialforceondrivingrollercanbedescribedbyfollowingexpression:

Where

iscircumferentialforceondrivingroller,

isthetensioninbeltatdrivingrollerentranceand

isthetensioninbeltatdrivingrollerexit.

Thefollowingconditionmustbesatisfiedbecausethebeltdonotpermittedtoslideondrivingroller[2].

Where

isthecoefficientoffrictionbetweenthebeltanddrivingroller,

isangleofthebeltenvelopingontheroller.

3.6Powercalculation

Powerismainlyconsumedinovercomingrunningresistance.Andsomepowerisusedinelevatingmaterialinslopingconveyor.Powerondrivingrollershaftcanbecalculatedbythefollowerexpression[2]:

Sothemotorpoweris:

Where

isafactorofsafetyand

istransmissiondeviceefficiency.

4Structuredesignofpipebeltconveyor

4.1Thelengthoftransitionsection

Figure2Lengthoftransitionsection

Transitionsectionisshowninfigure2.Thebeltisflatatdrivingrolleranddrivenroller.Thebeltisturnedfromflatbeltintotubularoneattransitionsection.Thelengthoftransitiondependsonthepermissibleextensionofbelt.Iftransitionsectionistooshort,additionaldeformationandstresswillbegreatinbothsidesofbelt.Thiswillresultdamagetobelt.Iftransitionsectionistoolong,distanceofairproofconveyanceinwholelinewillbeshortened.Generallyspeaking,thelengthoftransitionsectionequalsto25diametersinnylonbeltwhile50diametersinwireropebelt[3].

4.2Designofsupportingrollers

Parallelsupportingrollersmustbeusedneardrivingrolleranddrivenrollersothattheangleofthebeltenvelopingontherollerisbigenough.Butatotherpositionintransitionsectiontroughsupportingrollersareused.Thustheflatbeltcanbecometubularonegraduallyandadditionalstressatedgeofbeltcanbereduced.Sotroughangleisusually20°,30°,45°,60°and90°.Sinceimpactloadatmaterialentranceisinevitable,threegroupsofcushioningsupportingrollerscansevertoreducetheintensityofshockloadsandits'spacingisabout300～500mm[4].

Hexagonsupportingrollersarewidelyusedaftertheflatbeltbecomestubularonel5J•Rollerscanbeequippedonthesamesideortwosidesofthesupportingboard.iseasytopositioningrollerspreciselyandtheforceinbeltisuniformwhenthesixrollersareequippedonthesamesideofsupportingboard.Generallyspeaking,theadjacentrollersspacingshouldnotexceedthebeltthickness,usually4～8mm.Ifthespacingweretoobig,theedgeofbeltwouldjaminit.Therearethreerollersoneachsideofthesupportingboardwhenrollersareequippedontwosidesofit.Thelengthofrollercanbelongerthanthelengthofhexagonsideandthebeltcannotjaminthespaceofadjacentrollers.Ontheotherhand,theforceinsupportingboardisuniform.Rollersonsupportingboardareshowninfig.3andfig.4.

Figure3.Rollersonsamesideofsuppportingboard

Figure4.Rollersontwosideofsuppportingboard

Rigidityisgreatlyincreasedafterflatbeltbecomestubular.Sosupportingrollersspacingcanalsobeincreased.Supportingrollergroupsspacingwithloadisabout1.2mor1.0manditis3.0minreturninconventionalconveyor,whileitvarieswiththepipediameterinpipebeltconveyor.Thegreaterpipebdiameteris,thegreaterthespacin