机械制造专业外文翻译锤片式粉碎机.docx
- 文档编号:12028289
- 上传时间:2023-04-16
- 格式:DOCX
- 页数:16
- 大小:141.55KB
机械制造专业外文翻译锤片式粉碎机.docx
《机械制造专业外文翻译锤片式粉碎机.docx》由会员分享,可在线阅读,更多相关《机械制造专业外文翻译锤片式粉碎机.docx(16页珍藏版)》请在冰豆网上搜索。
机械制造专业外文翻译锤片式粉碎机
外文原文:
Hammermills:
hammer-mills
Inthefeedprocessingprocesstheremaybeanumberofingredientsthatrequiresomeformofprocessing.Thesefeedingredientsincludecoarsecerealgrains,cornswhichrequireparticlesizereductionwhichwillimprovetheperformanceoftheingredientandincreasethenutritivevalue.Thereareamanywaystoachievethisparticlesizereduction,herewearelookingatusinghammer-mills,forinformationonrollermills,seetherelatedlinksatthebottomofthispage.
Bothhammeringandrollingcanachievethedesiredresultofachievingadequatelygroundingredients,butotherfactorsalsoneedtobelookedatbeforechoosingthesuitablemethodtogrind.Excessivesizereductioncanleadtowastedelectricalenergy,unnecessarywearonmechanicalequipmentandpossibledigestiveproblemsinlivestockandpoultry.Formoreindepthinformationregardingwhatactuallyoccurstotheingredientsduringsizereductionpleaserefertothislink:
particlesizereduction.
Hammer-mills
Advantages:
-areabletoproduceawiderangeofparticlesizes
-Workwithanyfriablematerialandfiber
-easeofuse
-Lowerinitialinvestmentwhencomparedwitharollermill
-Minimalmaintenanceneeded
-Particlesproducedusingahammer-millwillgenerallybespherical,withasurfacethatappearspolished.
Disadvantages:
-Lessenergyefficientwhencomparedtoarollermill
-maygenerateheat(sourceofenergyloss)
-producegreaterparticlesizevariability(lessuniform)
-Hammer-millsarenoisyandcangeneratedustpollution
GeneralDesign
Themajorcomponentsofthesehammer-mills,showninthepicture,include:
-adeliverydeviceisusedtointroducethematerialtobegroundintothepathofthehammers.Arotorcomprisedofaseriesofmachineddisksmountedonthehorizontalshaftperformsthistask.-Free-swinginghammersthataresuspendedfromrodsrunningparalleltotheshaftandthroughtherotordisks.Thehammerscarryoutthefunctionofsmashingtheingredientsinordertoreducetheirparticlesize.-aperforatedscreenandeithergravity-orair-assistedremovalofgroundproduct.Actstoscreentheparticlesizeofthehammermilltoensureparticlesmeetaspecifiedmaximummeshsize.
Feederdesign
Materialsareintroducedintothepathsofthehammersbyavariablespeedveinfeeder.Thistypeoffeedercanhaveitsmotorslavedbyaprogrammablecontrollertothemaindrivemotorofthehammermill.Theoperationalspeedofthefeederiscontrolledtomaintainoptimumamperageloadingofthemainmotor.
Hammerdesignandconfiguration
Thedesignandplacementofhammersisdeterminedbyoperatingparameterssuchasrotorspeed,motorhorsepower,andopenareainthescreen.Optimalhammerdesignandplacementwillprovidemaximumcontactwiththefeedingredient.Hammermillsinwhichtherotorspeedisapproximately1,800rpm,shouldbeusinghammerswhicharearound25cm(~10inches)long,6.35cm(~2.5inches)wide,and6.4mm(0.25inches)thick.Forarotorspeedofabout3,600rpm,hammersshouldbe15to20cm(~6-8incheslong,5cm(~2inches)wide,and6.4mm(0.25inches)thick.
Thenumberofhammersusedforahammermillof1,800rpm,shouldbe1forevery2.5to3.5horsepower,andfor3,600rpm,oneforevery1to2horsepower.Hammersshouldbebalancedandarrangedontherodssothattheydonottrailoneanother.Thedistancebetweenhammerandscreenshouldbe12to14mm(~1/2inch)forsizereductionofcerealgrains.
Thevelocityortipspeedofthehammersiscriticalforpropersizereduction.Tipspeedisthespeedofthehammeratitstiporedgefurthestawayfromtherotor,andiscalculatedbymultiplyingtherotationalspeedofthedrivesource(shaftrpm)bythecircumferenceofthehammertiparc.Seethefollowingformula:
Acommonrangeoftipspeedsseeninhammer-millsiscommonlyintherangebetween5,000and7,000m/min(~16,000and23,000feetperminute).Whenthetipspeedsexceed23,000feetperminute,carefulconsiderationmustbegiventothedesignofthehammermill,thematerialsusedinitsconstruction,andthefabricationofallthecomponents.Simplychangingtherotationalspeedofthedrivesourceisnotarecommendedmethodofincreasinghammerspeedinexcessof23,000feetperminute.
Impactistheprimaryforceusedinahammer-mill.Anythingwhichincreasesthechanceofacollisionbetweenahammerandatarget;increasesthemagnitudeofthecollision;orimprovesmaterialtake-awayprovidesanadvantageinparticlesizereduction.Themagnitudeofthecollisionscanbeescalatedbyincreasingthespeedofthehammers.
ScreenDesign
Theamountofopenareainahammermillscreendeterminestheparticlesizeandgrindingefficiency.Thescreenmustbedesignedtomaintainitsintegrityandprovidethegreatestamountofopenarea.Screenopenings(holes)thatarealignedina60-degreestaggeredpatternoptimizeopenareawhilemaintainingscreenstrength.Thismethodwillresultina40percentopenareausing3.2mm(1/8inch)holesalignedon4.8mm(3/16inch)centers.
Feedproducersneedtopayparticularattentiontotheratioofopenscreenareatohorsepower.Recommendedratioforgrainswouldbe55cm2(~8-9inchessquare)perhorsepower(Bliss,1990).Notenoughopenareaperhorsepowerresultsinthegenerationofheat.Whentheheatgeneratedexceeds44Cto46C(120-125F),capacitymaybedecreasedasmuchas50percent.
Theremovalofsizedmaterialfromahammer-millisacriticaldesignfeature.Properoutputofmaterialaffectsnotonlytheefficiencyofoperation,butalsoparticlesize.Whenthecorrectratioofscreenareatohorsepowerisusedandproperdistancebetweenhammersandscreenfaceismaintained,mostofthecorrectlysizedparticleswillexitthescreeninatimelymanner.Anderson(1994)statedtheparticlesthatdonotpassthroughthescreenholesbecomepartofafluidizedbedofmaterialsweptalongthefaceofthescreenbythehigh-speedrotationofthehammers.Astheseparticlesrubagainstthescreenandeachothertheirsizeiscontinuallyreducedbyattrition.Thisexcessivesizereductioniscounterproductive.Energyiswastedintheproductionofheat,throughputisrestricted,andparticlesbecometoosmall.
Mostnewhammermillsareequippedwithanair-assistsystemthatdrawsairintothehammermillwiththeproducttobeground.Systemsaredesignedtoprovidereducedpressureontheexitsideofthescreentodisruptthefluidizedbedofmaterialonthefaceofthescreen,thusallowingparticlestoexitthroughscreenholes.Somefullcirclehammermillsaredesignedsothescreenisintwopieces.Itispossibletousealargerwholesizeontheupwardarcofthehammerstofurtherreducetheamountofmaterialonthefaceofthescreen.
HammerMillsHammers
Hammersareusedinsidethehammer-milltoimpactsmashingredientsupintosmallerparticles,makingitmoresuitableforuniformmixingandusageinfeed.Hammersareavailableinahugerangeofconfigurations,shapes,facingsandmaterials.Hammersareavailableassingleholedorwithtwoholes,withtwoholesallowingthehammerstobeusedtwiceasthewearisdonetooneendofthehammer;thehammercanberotatedandusedasecondtime.Theholefitsontoarodinsidethehammermillandswingstohitthematerial.
Dimensionsofahammer
A:
Thickness
B:
Width
C:
Diametertofitrodsize
D:
SwingLength
E:
TotalLength
HammerMillPerforatedScreens
Hammermillsscreensareusedinsideahammermilltoseparateparticlesizes.Particleofsmallenoughdiameterthathasbeensuccessfullygrindedbythehammermillpassesthroughthescreenandleavesthehammermillwiththeaidofthepneumaticsystem.
ParticleSizeReduction
SizeReduction:
Theinitialreductionofcerealgrainsbeginsbydisruptingtheouterprotectivelayeroftheseed(hull),exposingtheinterior,seethepicture.Continuedsizereductionincreasesboththenumberofparticlesandtheamountofsurfaceareaperunitofvolume.Itisthisincreasedsurfaceareathatisofprimaryimportance.Agreaterportionofthegrain'sinteriorisexposedtodigestiveenzymes,allowingincreasedaccesstonutritionalcomponentssuchasstarchandprotein.Theenhancedbreakdownofthesenutritionalcomponentsimprovesabsorptioninthedigestivetract.Theoveralleffectisincreasedanimalperformance.Sizereductionisalsousedtomodifythephysicalcharacteristicsofingredientsresultinginimprovedmixing,pelleting,and,insomeinstances,handlingortransport.
Hammermills:
Reducetheparticlesizeofmaterialsbyimpactingaslowmovingtarget,suchasacerealgrain,witharapidlymovinghammer.Thetargethaslittleornomomentum(lowkineticenergy),whereasthehammertipistravelingataminimumof4,880m/min(~16,000feetpermin)andperhapsinexcessof7,015m/min(~23,000feetpermin)(highkineticenergy).Thetransferofenergythatresultsfromthiscollisionfracturesthegrainintomanypieces.Sizingisafunctionofhammer-tipspeed;hammerdesignandplacement;screendesignandholesize;andwhetherornotairassistanceisutilized.
BecauseimpactistheprimaryforceusedinaHammermilltoreducethesizeoftheparticles,anythingthat;increasesthechanceofacollisionbetweenahammerandatarget,increasesthemagnitudeofthecollision,orimprovesmaterialtake-away,wouldbeadvantageoustoparticlesizereduction.Themagnitudeofthecollisionscanbeescalatedbyincreasingthespeedofthehammers.Anderson(1994)statedthatwhendrivespeedandscreensizewerekeptconstant,theincreasedhammer-tipspeedobtainedfromincreasedrotordiameterproducedparti
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- 机械制造 专业 外文 翻译 锤片式 粉碎机
![提示](https://static.bdocx.com/images/bang_tan.gif)