外文翻译-自移式液压支架

翻译部分英文原文SELF-ADVANCINGHYDRAULICPOWEREDSUPPORTSModernlongwallminingemployshydraulicpoweredsupportsatthefacearea.Thesupportnotonlyholdsuptheroof,pushesthefacechainconveyor,andadvancesitself,butalsoprovidesasafeenvironmentforallassociatedminingactivities.Thereforeitssuccessfulselectionandapplicationaretheprerequisiteforsuccessfullongwallmining.Furthermore,duetothelargenumberofunitsrequired,thecapitalinvestedforthepoweredsupportusuallyaccountsformorethanhalfoftheinitialcapitalforalongwallface.Thereforebothfromtechnicalandeconomicpointsofview,thepoweredsupportisaveryimportantpieceofequipmentinalongwallface.Theapplicationofmodernpoweredsupportscanbetracedbacktotheearly1950s.Sincethen,followingitsadoptionineverypartoftheworld,therehavebeencountlessmodelsdesignedandmanufacturedinvariouscountries.Butunfortunately,therestillisnouniformsystemofclassification.Asimplifiedclassificationisusedinthissection.sinceapoweredsupportconsistsoffourmajorcomponents(i.e.,canopy,cavingshield,hydrauliclegsorprops,andbaseplate),thewaysbywhichtheyareinterrelatedareusedforclassification.Inthisrespect,twofactorsaremostimportant:(1)presenceorabsenceofacavingshield-ifacavingshieldisincluded,thesupportisa“shield”type,otherwise,aframeorachock;(2)numberandtypeofarrangingthehydrauliclegs-sincesupportcapacityisgenerallyproportionaltothenumberofhydrauliclegs,itisimportanttospecifythenumberofhydrauliclegsthatasupporthas.Furthermore,thewaythehydrauliclegsareinstalledisimportant;forexample,averticalinstallationbetweenthebaseandthecanopyhasthehighestefficiencyofapplicationwhereasaninclinedinstallationbetweenthebaseandthecavingshieldhastheleastefficiencyinsupportingtheroof.Basedonthisconcept,therearefourtypesofpoweredsupport,thatis,theframe,chock,shield,andchockshield,inorderofevolutionoftheirdevelopment.However,itmustbenotedthatthetrendofdevelopmentineachtypeissuchthatitbecomeslessdistinguishableintermsofapplication.Thefourtypesofroofsupportscanbeobtainedforeitherlongwallretreatingoradvancingsystems,andtheyareavailableinstandard,one-web-back,andimmediateforwardsupport(IFS)versions.Withthestandardsystem,thewinningmachinetakesacutoraslice,andthearmoredfaceconveyorispushedoverbythehydraulicramsthatarefixedtothesupportunits.Thesupportunitsthenareadvancedsequentiallytotheconveyor.Withtheone-web-backsystem,asupportissetbackfromtheconveyorbyadevicethatautomaticallykeepstheleadingedgeofthesupportatafixeddistancefromtheconveyor.Thisallowseasyaccessthroughthefaceandemploysthestandardmethodofadvancing;i.e.,pushingtheconveyorfirst,andthenadvancingthesupport.WiththeIFSsystem,thesupportunitisadvancedtotheconveyorimmediatelyafterthecuttingmachinehaspassed,andtheforwardcanopyofthesupportunitislongenoughtosupportboththerecentlyandnewlyexposedroofsections.Afterthesupportshavebeenadvanced,theconveyorispushedover.FRAMETheframesupportisanextensionofthesinglehydraulicpropsconventionallyusedunderground.Thusitisthefirsttypedevelopedinmodernself-advancinghydraulicpoweredsupports.Itinvolvessettinguptwohydraulicpropsorlegsverticallyintandemthatareconnectedatthetopbyasingleortwosegmentedcanopies.Thetwosegmentedcanopiescanbehinge-jointedatanypointbetweenthelegsorinfrontofthefrontleg.Thebaseofthetwohydrauliclegsmaybeacircularsteelshoeweldedatbottomofeachlegorasolidbaseconnectingbothlegs(Fig.8.8).Generally,aframesupportconsistsoftwoorthreesetsofhydrauliclegs.Thesetmovingfirstisthesecondaryset,thesetmovinglateristheprimaryset.Thereisadouble-actingraminstalledbetweeneachset.Thepistonoftheramisconnectedtothesecondarysetandthecylindertotheprimaryset.Duringsupportadvance(Fig.8.9),theprimarysetissetagainsttheroofwhilethesecondarysetisloweredandpushedforwardbythepiston.Havingreachedthenewposition,thesecondarysetissetagainsttheroofwhiletheprimarysetisloweredandpulledforwardbythecylinder.Thedistanceofeachadvancerangesfrom20to36in.(0.500.91m).Fig.8.8Framesupporta-primarysetb-secondarysetABCFig.8.9MethodofadvancingtheframesupportTheframesupportisverysimple,butmoreflexibleorlessstablestructurally.Thereareconsiderableuncoveredspacesbetweenthetwopiecesofcanopywhichallowsbrokenroofrocktofallthrough.Consequently,theframesupportisnotsuitableforaweakroof.Frameshavebecomeseldomusedbecausetheyarelessstableandrequirefrequentmaintenance.CHOCKInachocksupport,thecanopyisasolidpieceandthebasemaybeeitherasolidpieceortwoseparatepartsconnectedbysteelbarsattherearand/orthefrontends.Inbothcasesalargeopenspaceisleftatthecenterforlocatingthedouble-actinghydraulicramwhichisusedtopushandpullthechainconveyorandthechockinawholeunit,respectively,adistinctivedifferencefromtheframesupport.Thissetupdesignedforthinseamswithtwolegsinthefrontandfourlegsintherear,separatedbyawalkwaisalsousedintheshieldsandchockshields.Again,allhydrauliclegsareinstalledverticallybetweenthebaseandthecanopy(Fig.8.10).Thenumberoflegsrangesfromthreetosix,butthefour-legchocksarebyfarthemostpopularones.Thesix-legchocksarey(Fig.8.10c).Forthesix-legchocks,thecanopyisgenerallyhinge-jointedabovethewalkway.Mostchockarealsoequippedwithagobwindowhangingattherearendofthecanopy.Thegobwindowconsistsofseveralrectangularsteelplatesconnectedhorizontallyatbothends.ABCFig.8.10SchematicsofvariouschocksupportInmostchocksupports,therearehingejointconnectionsbetweenthelegsandthecanopyandbetweenthelegsandthebase.Butinordertoincreasethelongitudinalstability,itisreinforcedmostlywithabox-shapedsteelframebetweenthebaseandeachleg.Alegrestoringdeviceisinstalledaroundeachlegatthetopofthebox-shapedsteelframe.Thechocksaresuitableformediumtohardroof.Whentheroofoverhangswellintothegobandrequiresinducedcaving,thechockscanprovideaccesstothegob.SHIELDShields,anewentryintheearlyseventies,arecharacterizedbytheadditionofacavingshieldattherearendbetweenthebaseandthecanopy.Thecavingshields,whichingeneralareinclined,arehinge-jointedtothecanopyandthebasemakingtheshieldakinematicallystablesupport,amajoradvantageovertheframesandthechocks.Italsocompletelysealsoffthegobandpreventsrockdebrisfromgettingintothefacesideofthesupport.Thustheshield-supportedfaceisgenerallyclean.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(Fig.8.11).A.Lemniscate.LB.Caliper.CC.Ellipse.EFig.8.11ThreetypesofmotionaltracesforleadingedgeoftheshieldcanopyA.Lemniscate.Thisisthemostpopulartype.Thecavingshieldandthebasearejointedbytwolemniscatebarswhichhaveatotaloffourhinges.Asthehydrauliclegsareraisedandlowered,thedimentionsofthelemniscatebarsareselectedsuchthattheleadingedgeofthecanopymovesupanddownnearlyvertically,thusmaintaininganearlyconstantunsupporteddistancebetweentheface-lineandtheleadingedgeofthecanopy.Thisisafeaturethatiswidelyconsideredmostdesirableforgoodroofcontrol.Thereareclearlimitsofminingheightwithinwhichtheleadingedgeofthecanopymovesnearlyvertically.Theselimitsarestrictlycontrolledbythedimentionalandpositionalarrangementsofthecanopy,cavingshield,lemniscatebars,andthebase.Beyondtheselimits,theedgeswillmoverapidlyawayfromtheface-linecreatingalargeunsupportedarea.B.Caliper.Inacalipershield,thecavingshieldandthebaseareconnectedbyasinglehinge.Whenthehydrauliclegsareraised,theleadingedgeofthecanopymovesinanarcawayfromtheface,thusincreasingtheunsupportedareaThisisconsideredbymostuserstheleastdesirablefeatureofthecalipershieldButinpracticeiftheseamthicknessvarieslittle,thedimentionalandpositionalarrangementofcanopy,cavingshield,andthebasecanbesodesignedthatthedistancechangeofunsupportedareawillnotbesignificant.Ontheotherhand,whenthelegsarelowered,itreducestheunsupportedarea.C.Ellipse.Inthistypethecavingshieldandthebasearesoconnectedthatwhenthehydrauliclegsaremovedupanddown,theleadingedgeofthecanopyfollowsanellipticaltrace.Thistypeisseldomused.CHOCKSHIELDThechockshieldcombinesthefeaturesofthechocksandtheshields.Assuchitpossessestheadvantagesofboth.Ifallofthefourorsixlegsareinstalledbetweenthecanopyandthebase,itiscalledachockshield.Thereareregularfourorsix-legchockshieldsinwhichalllegsareverticalandparallel.OthersformVorXshapes.Somecanopiesareasinglepieceandsomearetwopieceswithahydraulicramatthehingejoint.Thechockshieldhasthehighestsupportingefficiency.Theyaresuitableforhardroof.中文译文自移式液压支架液压支架广泛应用于现代长臂采煤工作面上。它不但能够支撑顶板、推进工作面刮板输送机、自行前移，而且能够为井下联合采煤作业提供一个安全的环境。因此，正确、合理地选择液压支架架型是长臂工作面采煤成功的前提和关键。此外，井下采煤需要大量的液压支架，通常对液压支架的资金投入占整个长臂采煤工作面初期投入的一半还要多。因此，从技术和经济的角度来看，液压支架在长臂工作面采煤中占据着非常重要的位置。现代液压支架的应用可以追溯到上个世纪50年代。从那时开始，支架在世界各个角落得到了广泛应用，各个国家都相继设计和制造了大量的液压支架。不过始终没有形成统一的分类体系。现在通常采用一种简化的方法对液压支架进行分类。由于液压支架主要有四个主要部分组成，即顶梁、掩护梁、液压立柱（支柱）和底座，因此常根据它们之间的相互连接方式进行分类。鉴于此，对液压支架的分类通常采用下列两种标准：1、根据掩护梁的有无分类，如果有掩护梁则属于掩护式支架，否则属于框架式或垛式支架；2、根据液压立柱的数量和安装方式分类，支架所能承受的负载一般与立柱的数量成比例，因此在介绍液压支架时指明其所具有的立柱的数量是非常有必要的。此外，液压立柱的安装方式也是非常重要的。例如，底座和顶梁垂直安装时，支架具有最高的工作效率，而底座和掩护梁倾斜安装时，工作效率比较低。基于上述思想，根据支架的发展历程，可将其分为四类，即框式支架、垛式支架、掩护式支架和支撑掩护式支架。然而，有必要指出的是，随着液压支架的应用越来越广泛，各种类型支架的差别正逐渐缩小。上述四种支撑顶板的液压支架可以应用于长臂工作面的回采和推进，常用的支护方式主要有标准支护、滞后支护和IFS（即时支护）支护三种类型。对于标准支护方式，采煤机通过截齿切割煤层，工作面输送装置通过安装在支架里的液压千斤顶向新的煤壁推近，然后支架一架一地向输送机连续移近。对于滞后支护方式，支架不可能靠近输送机，因为有一个装置自动地使支架前端与输送机保持一定的距离，使得能够较容易地通过采煤工作面，并且能够运用标准化推进方法，即先推移工作面输送机，再推移液压支架。对于IFS（即时支护）支护方式，随着采煤机向上采煤，液压支架迅速地向刮板输送机推近，支架的前端顶梁的长度足以支撑原有的和新裸露出的岩石顶板，液压支架向前推进后输送机再向前推移。框式支架框式支架是井下用常规单体液压支柱的延伸，也是现代自移式液压支架中最早出现的一种类型。它装有一前一后两个液压支柱，顶梁通常有整体式和铰接式两种。对于绞接式顶梁，顶梁由两块顶梁板在支架顶部连接而成，这两块顶梁板可以在两根立柱之间或前端支柱前面的任意位置处铰接。支架的底座可以是焊接在两个支柱底部的圆形钢板底靴，也可以是在两根立柱之间形成的牢固连接。（图8.8）图8.8框式液压支架通常，框式支架含有两根或三根液压立柱。支架移动时，首先动的是副架，然后是主架。在主架和副架之间装有一双作用液压缸，活塞杆固定在副架上，而缸体固定在主架上。支架推移时（图8.9），双作用液压缸活塞腔进液，主架支撑顶板而副架降柱被活塞杆推动前移，到达新的位置后，副架开始升柱支撑顶板，双作用液压缸活塞杆腔进液而活塞腔回液，主架降柱被液压缸缸体向前拉动至新的位置，从而完成一次移架操作。液压支架每次推移的距离在2036英寸(合0.50.91m)。a前支架b后移支架图8.9框式支架的移架方式框式支架结构简单、灵活，但是稳定性较差。相互连接的两块顶梁板之间有相当大的未遮盖空间，这使得破碎的顶板岩石冒落。因而，框式支架对松软顶板的适应性较差。框式支架的结构不稳定并且需要较频繁的维护和保养，这使得它的应用正变得越来越少。垛式支架.在垛式支架中，顶梁是整体式，底座可能是整体式，也可能是对分式，由两个分离的底座箱在前端或后端通过（弹簧）钢板或销轴相连接。支架底座无论是整体式还是对分式，支架中部都会留出足够的空间用来放置双作用液压千斤顶，该千斤顶能够使刮板输送机向前推进（推溜），还能使垛式支架向前推移（移架）。这也是垛式支架明显不同于框式支架的地方，这一推移千斤顶装置也广泛应用于掩护式支架和支撑掩护式支架当中。另外，在垛式支架中，所有的液压立柱都在底座和顶梁之间垂直安装（图8.10）。垛式支架通常采用36根立柱，但目前绝大多数垛式支架装有4根立柱。六柱垛式支架广泛应用于薄壁煤层的开采，其布置方式为前部2根立柱，后部4根立柱，前后两部分被一通道隔开。对六柱垛式支架来说，顶梁通常是在通道上方处铰接的。大部分垛式支架都在顶梁后端开有通向采空区的窗口，这些窗口是由很多矩形钢板在顶梁两端水平低连接而成的。大多数垛式支架的立柱和顶梁以及立柱和底座之间都是铰接的，但为了增加支架的纵向稳定性，通常在支架底座和各根立柱之间安装箱形钢式框架，钢式框架的上端（立柱四周）装有立柱复位装置。垛式支架对硬质顶板的适应性较强。当顶板在采空区上方被支撑好并且需要进行采掘时，支架可以提供通向采空区的通道。图8.10垛式支架的各种结构