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英文原文SelfadvancinghydraulicpoweredsupportModernlongwallminingemployshydraulicpoweredsupportsatthefacearea.Thesupportsnotonlyholdsuptheroof,pushesthefacechainconveyor,andadvancesitself,butalsoprovidesasafeenvironmentforallassociatedminingactivities.Thereforeitssuccessfulselectionandapplicationaretheprerequisiteforsuccessfullongwallmining.Furthermore,duetothelargenumberofunitsrequired,thecapitalinvestedforthepowersupportusuallyaccountsformorethanhalfoftheinitialcapitalforalongwallface.Thereforebothfromtechnicalandeconomicpointsofview,thepoweredsupportisaveryimportantpieceofequipmentinalongwallface.Theapplicationofmodernpoweredsupportscanbetracedbacktoearly1950s.Sincethen,followingitsadoptionineverypartoftheworld,therehavebeencountlessmodelsdesignandmanufacturedinvariouscountries.Butunfortunately,therestillisnouniformsystemofclassification.Asimplifiedclassificationisusedinthissection.Sinceapoweredsupportconsistsoffourmajorcomponentsi.e.,canopy,cavingshield,hydrauliclegsandprops,andbaseplate,thewaysbywhichtheyareinterrelatedareusedforclassification.Inthisrespect,twofactorsaremostimportant1presenceorabsenceofcavingshieldifacavingshieldisincluded,thesupportisashieldtype,otherwise,aframeorachock2numberandtypeofarrangingthehydrauliclegssincesupportcapacityisgenerallyproportionaltonumberofhydrauliclegs,itisimportanttospecifythenumberofhydrauliclegsthatasupporthas.Furthermore,thewaythehydrauliclegsareinstalledisimportantforexample,averticalinstallationbetweenthebaseandthecanopyhasthecavingshieldhastheleastefficiencyinsupportingtheroof.Basedonthisconcept,therearefourtypesofpoweredsupport,thatis,theframe,chock,shieldandchockshield,inorderofevolutionoftheirdevelopment.However,itmustbenotedthatthetrendofdevelopmentineachtypeissuchthatitbecomeslessdistinguishableintermsofapplication.Thefourtypesofroofsupportscanbeobtainedforeitherlongwallretreatingoradvancingsystems,andtheyareavailableinstandard,onewebback,andimmediateforwardsupportIFSversions.Withthestandardsystem,thewiningmachinetakesacutoraslice,andthearmoredfaceconveyorispushedoverbythehydraulicramsthatarefixedtothesupportunits.Thesupportunitsthenareadvancedsequentiallytotheconveyor.Withtheonewebbacksystem,asupportissetbackfromtheconveyorbyadevicethatautomaticallykeepstheleadingedgeofthesupportatafixdistancefromtheconveyor.Thisallowseasyaccessthoughthefaceandemploysthestandardmethodofadvancingi.e.,pushingtheconveyorfirst,andthenadvancingthesupport.WiththeIFSsystem,thesupportunitsisadvancedtotheconveyorimmediatelyafterthecuttingmachinehaspassed,andtheforwardcanopyofthesupportunitsislongenoughtothesupportboththerecentlyandnewlyexposedroofsections.Afterthesupportshavebeenadvanced,theconveyorispushedover.FRAMETheframesupportisanextensionofthesinglehydraulicpropsconventionallyusedunderground.Thusitisthefirsttypedevelopedinmodernselfadvancinghydraulicpoweredsupports.Itinvolvessettinguptwohydraulicpropsorlegsverticallyintandemthatareconnectedatthetopbyasingleortwosegmentedcanopies.Thetwosegmentedcanopiescanbehingejointedatanypointbetweenthelegsorinfrontofthefrontleg.Thebaseofthetwohydrauliclegsmaybeacircularsteelshoeweldedatbottomofeachlegorsolidbaseconnectingbothlegs.Generally,aframesupportconsistsoftwoorthreesetsofhydrauliclegs.Thesetmovingfirstisthesecondaryset,thesetmovinglateristheprimaryset.Thereisadoubleactingraminstalledbetweeneachset.Thepistonoftheramisconnectedtothesecondarysetandthecylindertotheprimaryset.Duringsupportadvance,theprimarysetissetagainsttheroofwhilethesecondarysetisloweredandpushedforwardbythepiston.Havingreachedthenewposition,thesecondarysetisagainsttheroofwhiletheprimarysetisloweredandpulledforwardbythecylinder.Thedistanceofeachadvancerangesfrom20to36in.0.500.91mTheframesupportisverysimple,butmoreflexibleorlessstablestructurally.Thereareconsiderableuncoveredspacesbetweenthetwopiecesofcanopywhichallowsbrokenroofrocktofallthrough.Consequently,theframesupportisnotsuitableforaweakroof.Frameshavebecomeseldomusedbecausetheyarelessstableandrequirefrequentmaintenance.CHOCKInachocksupport,thecanopyisasolidpieceandthebasemaybeeitherasolidorpieceortwoseparatepartsconnectedbysteelbarsattherearand/orthefrontends.Inbothcasesalargeopenspaceisleftatthecenterforlocatingthedoubleactinghydraulicramwhichisusedtopushandpullthechainconveyorandthechockinawholeunit,respectively,adistinctivedifferencefromtheframesupport.Thissetupisalsousedintheshieldsandchockshields.Again,allhydrauliclegsareinstalledverticallybetweenthebaseandthecanopy.Thenumberoflegsrangesfromthreetosix,butthefourlegchocksarebyfarthemostpopularones.Thesixlegchocksaredesignedforthinseamswithtwolegsinthefrontandfourlegsintherear,separatedbyawalkway.Forthesixlegchocks,thecanopyisgenerallyhingejointedabovethewalkway.Mostchockarealsoequippedwithagobwindowhangingattherearendofthecanopy.Thegobwindowconsistsofseveralrectangularsteelplatesconnectedhorizontallyatbothends.Inmostchocksupports,therearehingejointconnectionsbetweenthelegsandthecanopyandbetweenthelegsandthebase.Butinordertoincreasethelongitudinalstability,itisreinforcedmostlywithaboxshapedsteelframebetweenthebaseandeachleg.Alegrestoringdeviceisinstalledaroundeachlegatthetopoftheboxshapedsteelframe.Thechocksaresuitableformediumtohardroof.Whentheroofoverhangswellintothegobandrequiresinducedcaving,thechockscanprovideaccesstothegob.SHIELDShields,anewentryintheearlyseventies,arecharacterizedbytheadditionofacavingshieldattherearendbetweenthebaseandthecanopy.Thecavingshields,whichingeneralareinclined,arehingejointedtothecanopyandthebasemakingtheshieldakinematicallystablesupport,amajoradvantageovertheframesandthechocks.Italsocompletelysealsoffthegobandpreventsrockdebrisfromgettingintothefacesideofthesupport.Thustheshieldsupportedfaceisgenerallyclean.Thehydrauliclegsintheshieldsaregenerallyinclinedtoprovidemoreopenspacefortraffic.Becausethecanopy,cavingshield,andbaseareinterconnected,itcanwellresistthehorizontalforcewithoutbendingthelegs.Thus,unlikethesolidconstraintintheframe/chocksupports,thepinconnectionsbetweenthelegsandthecanopy,andbetweenthelegsandthebaseinashieldsupportmakeitpossiblethattheangleofinclinationofthehydrauliclegsvarieswiththeminingheights.Sinceonlytheverticalcomponentofhydrauliclegpressureisavailableforsupportingtheroof,theactualloadingcapacityoftheshieldalsovarieswiththeminingheights.Therearemanyvariationsoftheshieldsupports.Inthefollowing,sixitemsareusedtoclassifytheshields,whichenablesaunifiedterminologytobedevelopedforallkindsofshields.Thetypesofmotionaltracesofthecanopytip,legpositionsandorientation,numberoflegs,canopygeometry,andotheroptionaldesignsanddevicescanbeclearlyspecifiedbytheterminology.TYPESOFMOTIONALTRACESFORTHELEADINGEDGEOFTHECANOPY.Thisisthemostcommonlyrecognizedwayofclassifyingtheshield.Basedonthiscriterion,therearethreetypes,lemniscate,caliper,andellipse.Lemniscate.Thisisthemostpopulartype.Thecavingshieldandthebasearejointedbytwolemniscatebarswhichhaveatotaloffourhinges.Asthehydrauliclegsareraisedandlowered,thedimentionsofthelemniscatebarsareselectedsuchthattheleadingedgeofthecanopymovesupanddownnearlyvertically,thusmaintaininganearlyconstantunsupporteddistancebetweenthefacelineandtheleadingedgeofthecanopy.Thisisafeaturethatiswidelyconsideredmostdesirableforgoodroofcontrol.Thereareclearlimitsofminingheightwithinwhichtheleadingedgeofthecanopymovesnearlyvertically.Theselimitsarestrictlycontrolledbythedimentionalandpositionalarrangementsofthecanopy,cavingshield,lemniscatebars,andthebase.Beyondtheselimits,theedgeswillmoverapidlyawayfromthefacelinecreatingalargeunsupportedarea.Caliper.Inacalipershield,thecavingshieldandthebaseareconnectedbyasinglehinge.Whenthehydrauliclegsareraised,theleadingedgeofthecanopymovesinanarcawayfromtheface,thusincreasingtheunsupportedarea.Thisisconsideredbymostuserstheleastdesirablefeatureofthecalipershield.Butinpracticeiftheseamthicknessvarieslittle,thedimentionalandpositionalarrangementofcanopy,cavingshield,andthebasecanbesodesignedthatthedistancechangeofunsupportedareawillnotbesignificant.Ontheotherhand,whenthelegsarelowered,itreducestheunsupportedarea.Ellipse.Inthistypethecavingshieldandthebasearesoconnectedthatwhenthehydrauliclegsaremovedupanddown,theleadingedgeofthecanopyfollowsanellipticaltrace.Thistypeisseldomused.CHOCKSHIELDThechockshieldcombinesthefeaturesofthechocksandtheshields.Assuchitpossessestheadvantagesofboth.Ifallofthefourorsixlegsareinstalledbetweenthecanopyandthebase,itiscalledachockshield.Thereareregularfourorsixlegchockshieldsinwhichalllegsareverticalandparallel.OthersformVorXshapes.Somecanopiesareasinglepieceandsomearetwopieceswithahydraulicramatthehingejoint.Thechockshieldhasthehighestsupportingefficiency.Theyaresuitableforhardroof.中文译文自移式液压支架现代长壁工作面采煤已经在开采区使用液压支架。液压支架不仅支撑顶板,推动刮板输送机工作面和自移式支架本身,而且还为相关的采煤设备提供一个安全的工作环境。因此正确的选择和应用液压支架是长壁工作面采煤成功的先决条件。此外,由于对液压支架需求数量很大,对液压支架的投资经常要占到长壁采煤工作面
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