电梯安装电梯安全中英文对照外文翻译文献.docx
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电梯安装电梯安全中英文对照外文翻译文献.docx
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电梯安装电梯安全中英文对照外文翻译文献
电梯安装电梯安全中英文对照外文翻译文献
(文档含英文原文和中文翻译)
ELEVATORSAFETY:
GIVETHEMINERABRAKE
ABSTRACT
Overafive-yearperiod,therewereatleast18documentedcasesofascendingelevatorsstrikingtheoverhead.Insomecases,theaccidentsresultedinseriousinjuriesorfatalities.Theseaccidentsoccurredoncounterweightedelevatorsasaresultofelectrical,mechanical,andstructuralfailures.Elevatorcarsarefittedwithsafetiesthatgriptheguiderailsandstopafallingcar;however,thesedevicesdonotprovideprotectionintheupwarddirection.
Rulesandregulationsapplyingtoelevatorsafetyhavecomeunderreviewinresponsetotheseaccidents.Somegoverningauthoritieshavealreadyrevisedtheirregulationstorequireascendingcaroverspeedprotection.Thispaperwilldiscussbasicelevatordesign,hazards,regulations,andemergencybrakingsystemsdesignedtoprovideascendingcaroverspeedprotection.Inaddition,acase-studyreportonapneumaticropebrakesysteminstalledandtestedonamineelevatorwillbediscussed.
INTRODUCTION
Elevatorsincorporateseveralsafetyfeaturestopreventthecarfromcrashingintothebottomoftheshaft.Safetiesinstalledonthecarcanpreventthistypeofaccidentfromoccurringwhenthemachinebrakefailsorthewireropessuspendingthecarbreak.However,theinherentdesignofthesafetiesrendertheminoperativeintheascendingdirection.
Intheupwarddirection,themachinebrakeisrequiredtostopthecageIrvhenanemergencyconditionoccurs.Undernormaloperation,themachinebrakeservesonlyasaparkingbrakedtoholdthecageatrest.However,whenanemergencyconditionisdetected,modernelevatorcontrolsystemdesignsrelysolelyonthemachinebraketostopthecar.
IntheUnitedStatesminingindustry,theaccidenthistoryhasproventhatthisisnotthebestcontrolstrategy[2],[3].Theseaccidentsoccurredwhentheretardingeffortofthedrivemotorwasdefeatedwhenthemechanicalbrakeswereinoperative.Thisallowedthecounterweighttofalltothebottomoftheshaft,causingthecartooverspeedandstriketheheadframe.Thehigh-speedelevatorcrashesintotheoverheadstructurecausedextensivemechanicaldamageandpotentiallyfatalinjuries.
ELEVATORDESIGN
Abasicunderstandingofelevatoroperationisrequiredinordertoassessthesafetyhazardspresentanddeterminetheaccidentpreventmethodsavailable.Figure1showsacompleteviewofamineelevator.
Fig.1MicoElevator
SUSPENSIONriCPCS
Inatypicalelevator,theearisraisedandloeredbysixtoeightmotor–drivenwireropesthatareattachedtothetopofthecaratoneend,travelaroundapairofsheaves,andareagainattachedtoacounterweightattheotherend.
Thecounterweightaddsacceleratingforcewhentheelevatorcarisascendingandprovidesaretardingeffortwhenthecarisdescendingsothatlessmotorhorsepowerisrequired.Thecounterweightisacollectionofmetalweightsthatisequaltotheweightofthecarcontainingabout45%ofitsratedload.Asetofchainsareloopedfromthebottomofthecounterweighttotheundersideofthecartohelpmaintainbalancebyoffsettingtheweightofthesuspensionropes
Guiderailsthatrunthelengthoftheshaftkeepthecarandcounterweightfromswayingortwistingduringtheirtravel.Rollersareattachedtothecarandthecounterweighttoprovidesmoothtravelalongtheguiderails.
Thetractiontoraiseandlowerthecarcomesfromthefrictionofthewireropesagainstthegroovedsheaves.Themainsheaveisdrivenbyanelectricmotor.
Motor-generator(M-G)setstypicallypro-videtodcpowerforthedrivemotor.Newersystemsuseastaticdrivecontrol.Theelevatorcontrolsvarythemotor'sspeedbasedonasetoffeedbacksignalsthatindicatethecar'spositionintheshaftway.Asthecarapproachesitsdestination,aswitchnearthelandingsignalsthecontrolstostopthecaratfloorlevel.Additionalshaftwaylimitswitchesareinstalledtomonitorovertravelconditions.
Theworstfearof'litanypassengersisthattheelevatorwillgooutofcontrolandfallthroughspaceuntilitsmashesintothebottomoftheshaft.Thereareseveralsafetyfeaturesinmodernelevatorstopreventthisfromoccurring.Thefirstisthehigh-strengthwireropesthemselves.Each0.625-in-diameterextra-high-strengthwireropecansupport32,000lb,orabouttwicetheaverageweightofamineelevatorfilledwith20passengers.Forsafety'ssakeandtoreducewear,eachcarhassixtoeightofthesecables.Inaddition,elevatorshavebuffersinstalledattheshaftbottomthatcanstopthecarwithoutkillingitspassengersiftheyarestruckatthenormalspeedoftheelevator
Aspreviouslydiscussed,modernelevatorshaveseveralspeedcontrolfeatures.Iftheydonotwork,thecontrolswilldisconnectthemotorandapplythemachinebrake.Finally,the
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