会员注册 | 登录 | 微信快捷登录 支付宝快捷登录 QQ登录 微博登录 | 帮助中心 人人文库renrendoc.com美如初恋!
站内搜索 百度文库

热门搜索: 直缝焊接机 矿井提升机 循环球式转向器图纸 机器人手爪发展史 管道机器人dwg 动平衡试验台设计

   首页 人人文库网 > 资源分类 > DOC文档下载

外文翻译--自移式液压支架.doc

  • 资源星级:
  • 资源大小:40.50KB   全文页数:7页
  • 资源格式: DOC        下载权限:注册会员/VIP会员
您还没有登陆,请先登录。登陆后即可下载此文档。
  合作网站登录: 微信快捷登录 支付宝快捷登录   QQ登录   微博登录
友情提示
2:本站资源不支持迅雷下载,请使用浏览器直接下载(不支持QQ浏览器)
3:本站资源下载后的文档和图纸-无水印,预览文档经过压缩,下载后原文更清晰   

外文翻译--自移式液压支架.doc

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.

注意事项

本文(外文翻译--自移式液压支架.doc)为本站会员(英文资料库)主动上传,人人文库网仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对上载内容本身不做任何修改或编辑。 若此文所含内容侵犯了您的版权或隐私,请立即通知人人文库网([email protected]),我们立即给予删除!

温馨提示:如果因为网速或其他原因下载失败请重新下载,重复下载不扣分。

copyright@ 2015-2017 人人文库网网站版权所有
苏ICP备12009002号-5