外文翻译牧草小区播种机排种器的设计及试验4400字外文文献毕业论文Word下载.docx

外文翻译牧草小区播种机排种器的设计及试验4400字外文文献毕业论文Word下载.docx

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专业：

机械设计制造及其自动化

班级：

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姓名：

指导教师：

DevelopmentandexperimentofseedmeteringforgrassplotSeeder

YangSong,ZhangShumin,YiJintao,WengQiang

（CollegeofEngineering,ChinaAgriculturalUniversity,Beijing100083，China）

Abstract:

Inordertodevelopagrassplotseeder,whichissuitableforcultivationoffinegrassvarieties,aseedmeteringtestplatformwasdevelopedwhichhasaspecialdesignedtransmissionmechanismandaseedcupwithanadjustablering.Severalkindsofseedscanbefedbyfeedingmechanisminfeedingcupwhenseedingshaftaswellasdistributorconerotatesonecompleterevolution.Seedmotionandtherelationshipbetweenseedoutletandseedcupwereanalyzedinthispaper.Resultoforthogonalexperimentshowedthatthenumberofsweeperbladeswasoneofthemaininfluencingfactorsofthevariationcoefficientofseedinguniformity.When12sweeperbladesand9groovesconewereusedintest,thevariationcoefficientofthePacesetter’sseedinguniformitygottotheminimumvalue16.46%.Thisresearchprovidesareferenceforgrassplotseeder’sdevelopment.

Keywords:

agriculturalmachinery,mechanisms,stressanalysis,plotseeder,grasscultivation

doi：

10.3969/j.issn.1002-6819.2012.z2.013

Documentcode:

A

ArticleID:

1002-6819（2012）-Supp.2-0072-06

CLCnumber:

S223.2+6

0.Introduction

Itisimportanttoconductcomparabletestsinexperimentalplotswithbreeding,species,nutritionalvalueandproductionresearchforgrassresourceandanimalhusbandry[1].Therefore,plotseederplaysakeyrolefortheresearchandrangelanddevelopment.

Thedesignrequirementsofgrassplotseederaresimilarwithconventionalplotseeder,whichneedtofeedauniformamountofseedoverthelengthofaplotandseedmeteringmustbecleanedbetweencontiguousplotsbecauseseveralspeciesandmixturesmaybeinthesameexperiment.

Numerousplotseedershadbeendevelopedforagronomictrialsofseedingbeforeitwasappliedtoseedingrangeland.During1958to1960,EgilØ

yjorddesignedandimproveda4-row,a6-rowanda10-rowplotseeders,respectively.In1970’s,Ø

yjordplotseederswereexportedfromNorwayto57countries[2].

HaroldG.Marshalldesignedaplotdrillwithamultipleoutletconewhichisprovidedwithmultiplestraightgrooves[3].

Mostoftheplotdrillsareunsuitableforuseinrangelandtrialsbecausetheycannotseedchaffygrassseedortheycannotbeusedinrangelandseedbeds.In1978,KennethPVogeldevelopedanexperimentalplotdrillbymountingaconeseederandaspinneronamodifiedrangelanddrillandseeded14speciesofgrass.KennethPVogelfoundthatsomesmallseedswouldcauseerraticfeedingandincompletecleaningofthecone,butbothproblemscanbesolvedbydumpingfinevermiculiteintotheconebeforetheseedisadded[6].REBarkerdevelopedanequipmentwhichisadaptableforvarietytrialsforsmallgrains,grassesandlegumes[3,7].

InChina,theresearchandapplicationofplotoperationmachinehaveagreatdevelopmentinlastseveraldecades,buttheyarestillbackwardincomparisonwiththatofadvancedcountriesintheworld,andtheplotseederforgrassbreedinghasnotbeenreported[8-10].

Theessentialelementofaplotseederisseedmetering,whichiscomposedoftheconewhichrotatesonecompleterevolutionwhentheplantermovesoveraplot,andseedcupcenteredabovetheconeapex.Seedsarepouredintothecupbyfeedingmechanismandthendumpedintotheconebyrisingthecup.Traditionally,theseedcupcanberaisedbyhandorbyusinganelectromagneticliftingdevice[10-12].Andtheproblemoferraticfeedingandincompletecleaningcanbesolvedbyaddinggranularmixturebutthemixturemayexceedthecapacityofthecone.

Forsolvingtheproblemsmentionedabove,agrassplotseederwasdesignedandaseedmeteringtest-bedwasfabricatedbasedonstudyofdomesticandforeignresearch.

1.Structureandprinciple

Theseedmeteringdesignedinthispaperincludesseedfeedingmechanism,transmissionmechanismandseedingmechanism（Fig.1）.Theseedsinseedingbaseplatewillbepushedbysweeperblades（notshowninFig.1）andpourintoseedoutlettubewhenseedingshaftaswellasdistributorconerotatesonecompleterevolution.Thereare18feedingcupsinfeedingmechanism.Allthefeedingcupsareconnectedwithafeedingshaft,whichisdrivenbyagearwhichmeshesoncewithmiddleshaftwhenitrotatesonecompleterevolution.Andthefeedingcupsinthefeedingmechanismtraywillmoveforward20°

alongcircleandthenbehaltedbyalocationdevice.Seedsinthefeedingcupabovetheseedcupwilldumponthecone.（Chinesepatentnumber:

201120192091.5）.Theclearancebetweendistributorconeandseedcupwhichhassomethingtodowithseedsizecanbeadjustedbyadjustableringbeforehand.

1.Driveshaft2.Seedoutlettube3.Seedingbaseplate4.Distributorcone5.Seedinggrooves6.Adjustablering7.Seedcup8.Feedingcup9.Feedingmechanismtray10.Feedingshaft11.Middleshaft12.Seedingshaft

Fig.1Structurediagramofseedmetering

2Analysisandcalculationofseedingprocess

2.1Analysisofmotioninseedcup

Whenseedsarepouredintoseedcup,itishopedthatmostpartoftheseedscandroptotheareaaroundapexofthedistributorcone,sothatseedinguniformitycouldbeimproved.Supposethatonlygravityforceactsoneachseedwithairresistanceneglected,andthenmotiontrackoftheseedwillbeparabola（Fig.2）.Takingtheinitialpointoftheparabolaastheoriginofthesystemcoordinates,andthehorizontalspeedofseedisatthepositivedirectionofxaxis.

Note:

ωistheangularvelocityofdistributorcone,rad/s;

x,yarecoordinatesoftheseed;

x′isthedistancebetweeninitialpointofmotionandedgeoftheseedcup,m;

Distheopeningdiameteroftheseedcup,m;

disthediameterofseedcup,m;

histheverticaldistancebetweeninitialpointofmotionandtheplaneofloweredgeoftheconicalinsidewall;

θisbaseangleoftheconicalinsidewall;

Listheverticaldistancebetweenseedcupopeningandapexofthedistributorcone,m;

sistheclearancebetweendistributorconeandseedcup,m.

Fig.2Partsectionedviewofseedmotion

Iftheseedcandroptotheareaofthedistributorconeapexattimet,itscoordinatesxandywillbewrittenas

Where,Xisxcoordinateoftheseed,m.Yisycoordinateoftheseed,m.Visoriginalhorizontalspeedoftheseed,whichequalstolinearvelocityofthefeedingcup,m/s.Distheopeningdiameteroftheseedcup,m.x′isthedistancebetweeninitialpointofmotionandedgeoftheseedcup,m.gisaccelerationofgravity,g/s2.Listheverticaldistancebetweenseedcupopeningandapexofthedistributorcone,m.FromtheFormula

（1）,itisobtainedthat

Substitutingformula（3）intoformula

（2）,theLisfollowedas

Formula（4）indicatestherelationshipbetweenLandD,Vandx′.

Toimprovetheseedinguniformity,theseedsalsoshouldnotcollidewiththeconicalinsidewalloftheseedcup.Whentheseedsdropdowntotheplaneofloweredgeoftheconicalinsidewall,Y=h,tcanbecalculatedfromFormula

（2）andisfollowedas

Toavoidcollidingwiththeconicalinsidewalloftheseedcup,thedisplacementoftheseedshouldbefollowedas

SubstitutingFormula

（1）and（5）intoFormula（6）,theVisfollowedas

Formula（4）and（7）aredesignrequirementsthatseedscandroptotheareaaroundapexofthedistributorcone,whichprovidesadesignreferenceforfeedingmechanismandseedcup.

2.2Relationshipbetweenrotatingspeedofconeandseedoutlet

Thedimensionsofdistributorconeaswellasthedimensionsofseedoutletontheseedingbaseplate`havetosatisfycertainconditionbecausetheconeandseedingbaseplatemustbecompletelycleanedafteroneseedingrevolution.

Supposethattheseeds’rotationalradiusintheseedingbaseplateisr（m）,theangularvelocityofdistributorconeisω（rad/s）.Theseed,whichonlygravityforceactson,ispushedbysweeperbladeandfallsintoseedoutlet（Fig.3）.

AccordingtoFormula

（2）,thetimeoftheseedfallingintoseedoutletisfollowedas

Andhorizontaldisplacementoftheseedmustbelessthansectionaldimensionoftheseedoutlet,thatis

Themaximumspeedoftheseedpushedbysweeperbladeisv=rω,andtheangularvelocityofdistributorconeωisfollowedas

Where,d′isdiameteroftheseed,m.Aissectionaldimensionoftheseedoutlet,m.visthemaximumspeedoftheseed,m/s.

Inordertoavoidmissingseedingandtheseedbeingstuckbybladeandseedoutlet,distributorconeandseedoutletshouldbedesignedaccordingtoFormula（8）.Infact,grassplotbreedingneedstoimplementsowinginstrip,therefore,acertainamountofseedswilldroptoseedoutletsimultaneously.Therefore,theseedoutlethastodesignwiderthantheoreticalvalueinsectionaldimension.

2.3Designoffeedingmechanismandrotatingspeedofcone

ThePlotSowingRate（sowingrateinaplot,PSRbriefly）hastobefiguredoutbecausetheamountoftheseedwhichwouldbeseededinoneplotdeterminesvolumeofafeedingcup（Table1）.SupposethatunitofPSRisgram,andthelengthofaplotis10m,unifyallunitsanditiscomputedby

Where,Qissowingrate,kg/hm2;

Bisrowspacing,m;

Sisthelengthofaplot,m;

Takingtallfescueforexample,theitssowingrateis22.5-37.5kg/hm2,rowspacingis0.3m,andthemaximumPSRoftallfescueis11.25g.

AccordingtothemaximumvolumesofPSR,itisfoundthat12gChineseleymushasthelargestvolume,whichcanbecalculatedfordesignreference.Thedesignvolumeis5.55×

103mm3,slightlylargerthan