机械类文献翻译采煤机.docx

机械类文献翻译采煤机.docx

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机械类文献翻译采煤机

英文原文

THESHEARER

Shearer

Longwallequipmentconsistsofthreemajorcomponents:

thehydraulicallypoweredroofsupport,thechainconveyor,andthecoal-cuttingmachine.

Thetwodifferenttypesofcoal-cuttingequipmentusedincoalminesareshearersandplows.

Plowsareusedinlowseams,42in.orless.Theunitconsistsofsteelconstructionequippedwithcarbon-tippedbits.Thispassivesteelunitisengagedtoaguidingsystemonthefaceconveyor.Anendlessroundlinkchainpoweredbysynchronizedelectricdrivesoneachendofthefaceconveyorpullstheplowbodyatspeedsbetween120and420ft/minalongtheface.

Forthecuttingprocesstheplowhastobeforcedagainstthecoalface.Thisisdonebyhydrauliccylinderattachedtothegobsideofthefaceconveyorandtothebaseofthesupports,orbyaseparatehydraulicprop.Forcesofbetween1and3tonsareappliedpercylinder.

Aplowdriveisattachedtoeachdriveframeofthefaceconveyor.Only30%to60%ofthedrivepowersuppliedtotheplowisusedforcuttingandloadingofcoal;theremainderislostinfriction.Thismeansthatthepowerlossisconsiderablyhigherthanthatofashearer,whichuses75%to85%ofitspowerfortheremovalofthecoal.Asaresult,ratherlargedrivesarerequiredatthefaceends.

Althoughtherearemanymodels,theshearerhasseveralcommonbasiccomponents.Adouble-endedranging-drumshearer（Fig.8.1）,forexample,consistsoffourmajorcomponents:

electricmotors,gearheads,haulageunit（powerpack）,andcuttingdrums.

Theelectricmotorrangingfrom300to1000horsepower（223~750kW）isthepowersourcefortheshearer.Itprovidespowertorunthehydraulicpumpsinthehaulageunitandthegearheadsforthecuttingdrum.Thelarge-capacityshearersaregenerallyequippedwithtwoelectricmotors:

oneforthehaulageunitandonegearheadandtheotherfortheothergearheadandotherancillaryequipment.Themotorscanberemotelycontrolled.

Therearetwogearheads,oneontheleft-handtheotherontheright-handsideoftheshearer.Eachgearheradconsistsofagearheadgearboxandarangingarm.

Thecuttingdrumislacedwithspiralvanesonwithspiralvanesonwhichthecuttingbitsaremounted.Itsdiameterrangesfrom34to72in.（0.86~1.83m）withrotationalspeedsfrom30to105rpm.Thetrendsaretowardfewerbutlargerbitsandslowerdrumspeedforbettercuttingefficiencyandlesscoaldustproduction.Thedrumsarealsoequippedwithpowercowlstoincreasethecoalloadingefficiency.Thepowercowlisusuallylocatedbehindthecuttingdrum.Forthatreason,itcanberotatedafull180º.

Theelectricmotor,haulageunit,andgearheadboxescombinetoformtheshearer’sbodywhichismountedontheunderframe.Theunderframehasfourslidingshoes.Theface-sideshoesarefittedandrideontheface-sidetopguideofthefaceconveyorpan,andtheothertwogob-sideslidingshoesarefittedonaguidetubetopreventderailment.Thetrammingapedoftheshearerrangesfrom19to46ft/min（5.8~14.0m/min）.

Inaddition,theshearerisequippedwithauxiliaryhydraulicpumpsandcontrolvalvesforoperatingtherangingarmsandpowercowls,watersprayingdevices,cable,chainanchorageandtensioners,andsoon

Inselectingtheshearer,miningheightshouldfirstbeconsidered;thatis,thediameterofthecuttingdrum,bodyheight,lengthoftherangingarm,andswinganglemustbeproperlyselected.Forthedouble-endedranging-drumshearer,themaximumminingheightcannotexceedtwicethediameterofthecuttingdrum.Theminingheightcanbedeterminedby（Fig.8.3）

H=Hb-B/2+Lsinα+D/2

WhereH=seamthicknessorminingheight

Hb=shearer’sbodyheight

B=bodydepth

L=lengthoftherangingarm

α=theanglebetweentherangingarmandthehorizontallinewhentherangingarmisraisedtoitsmaximumheight

D=diameterofthecuttingdrum

Forexample,fortheEichhoffEDW-170Ldoubleranging-drumshearer,Hb=4.3ft,L=3.90ft,α=52°，andD=5.3ft.ItsmaximumcuttingheightisH=9.2ft..

Typesofmodernshearers

Sinceitsfirstappearancein1954,theshearerhasundergonecontinuouschangesbothincapabilityandstructure.Itisnowthemajorcuttingmachineinlongwallcoalfaces.Therearetwotypesofshearers,single-anddouble-drum.Intheearliermodels,thedruminthesingle-drumshearerismountedontheshearer’sbodyandcannotbeadjustedforheight.Thereforeitisnotsuitableforareaswherethereareconstantchangesinseamthicknessandfloorundulation.Thusthesingle-endedfixed-drumshearerisusedmostlyforthinseams.

Figure6.10showsasingle-drumshearerwitharangingarm.Thecuttingdrumismountedattheveryendoftherangingarm.Therangingarmcanberaisedupanddownbyhydrauliccontroltoaccommodatethechangingseamthicknessandfloorundulation.Butwhentheseamexceedsacertainthickness,thesingle-drumshearercannotcuttheentireseamheightinonecutandareturncuttingtripisnecessarytocompleteafullwebcut.Furthermore,sincethedrumislocatedontheheadentryside,itgenerallyrequiresanicheinthetailentryside.Anicheisaprecutfaceend,onewebdeepandashearer’slengthlong.Withanicheatthefaceendtheshearercanturnaround.

Nowadays,thedoubleranging-drumshearersareusedpredominantly.Theshearercutsthewholeseamheightinonetrip.Thetwodrumscanbepositionedtoanyrequiredheight（withinthedesignedrange）duringcuttingandloweredwellbelowthefloorlevel.Thearrangementofthedrumsenablesthewholeseamtobecutineitherdirectionoftravel,therebyensuringrapidfaceadvanceandshorteningroofexposuretime.Therearevarioustypesofdoubleranging-drumshearers.Basedonthelocationofthedrums,therearetwotypes:

onewithonedrummountedoneachsideoftheshearer’sbodyandtheotherwithbothdrumsmountedononesideofthemachine.Theformertypeisthemostwidelyused.Itsadvantageisthatwithonedrumoneachsideoftheshearer,itcansumpineitherdirection.Duringthecuttingtrip,theleadingdrumcutstheupper70%oftheseamheightwhilethereardrumcutsthelower30%andcleansupthebrokencoalonthefloor.Thetwodrumsareapproximately23~33ft（7~10m）apart.Whenthesheareristravelingintheoppositedirectiontothatofthefaceconveyor,thecoalcutbytheleadingdrumhastopassundertheshearer’sbody,whichincreasesthemovingresistanceoftheshearerandthefaceconveyorandcouldcausea“crowding”condition.Ifthebrokencoalistoolarge,itmayblocktheshearerandstoptheoperation.Ingeneral,whentheshearerandthefaceconveyoraretravelingintheoppositedirections,approximately70%ofthecoaltakenbytheleadingdrumwillpassundertheshearer.Butwhentheyaretravelinginthesamedirection,thecoaltakendownbythereardrumtogetherwiththefloatcoalfromthefloorconstitutetheapproximately30%ofthecoalthathastopassundertheshearer.Theformercaseconsumes25%morepowerthanthelatter.Ascomparedtothesingle-endedshearer,theunderframeofthedouble-endedshearerishigher,therebyensuringasufficientcrosssectionforcoalpassage.

Basedonthemethodofadjustingtheheightofthecuttingdrum,therearealsotwotypesofshearers:

ranging-armshearerandgearheadshearer.Theformeroneiscommonlyused,whereasthelatteroneisarecentdevelopment.Theadvantageofthegearheadsheareristhatthehaulageunitislocatedatthecenteroftheshearer’sbodyandmountedontheunderframe.Onbothsidesofthehaulageunit,thereisagearhead.Eachgearheadcontainsanelectricmotorandaspeed-reductionunit.Thegearheadisraisedandloweredbyanadjustablehydraulicram.Theadjustablerangeofcuttingheightislarge.Itcanreachupto4.6ft（1.4m）.

Basedonthemountingrelationbetweentheshearerandthefaceconveyor,therearealsotwotypes:

theregulartypewhichridesontheconveyorandthein-webshearerwhichmovesonthefloorinfrontoftheconveyor.Thein-webshearerisusedmainlyforthethinseams.Asitmovesalongtheface,theleadingdrumcutsthecoal,makingasufficientspaceforthepassageofthepassageoftheshearer’sbody.

Haulageoftheshearer

Therearetwotypesofshearerhaulage:

chainandchainless.Thesearediscussedseparatelyinthefollowingparagraphs.

（1）Chainhaulage

Thehaulagechainisaround-linkchainwhichextendsalongthewholefacewidthandisfixedonbothendsattheheadandtaildrivesofthefacechainconveyor,respectively.Thechainalsopassesthroughthedrivinganddeflecting（orguiding）sprocketsinthehaulageunitoftheshearer.Asthedrivingsprocketrotates,itsteethtraptothematchingchainlinksandmovealongthenonmovinghaulagechain,therebypullingthesheareralong.Whenthedrivingsprocketrotatescounterclockwise,theshearermovestotheright.Conversely,whenthesprocketrotatesclockwise,theshearermovestotheleft.Thatpartofthechaininfrontofthemovingshearerisgenerallytightoronthetensionedsidewhereastheotherside,behindthemovingshearer,isslackorontheslackside.

Thetotalresistanceencounteredbyacuttingshearerconsistsmainlyofthecuttingresistanceofthedrum,coalloadingresistance,andthefrictionalresistancebetweentheconveyorandtheshearer.Thesummationofthethreetypesofresistanceisthetotalhaulageresistanceoftheshearer.Thehaulageunitmustprovidesufficienthaulagepowertoovercomethetotalhaulageresistancesothattheshearercanmovealongsmoothly.InFig.6.15thetensileforceinthetensionedsideisP2andthatintheslacksideisP1.Sincethehaulageforce（P2）isthesummationofP1andP,ifthechainontheslacksi