




已阅读5页,还剩1页未读, 继续免费阅读
版权说明:本文档由用户提供并上传,收益归属内容提供方,若内容存在侵权,请进行举报或认领
文档简介
AHIGH-POWERHYDRAULICDRILLFORBREAKINGHARDROCKF.F.VoitsekhovskayaUDC622.01.232.7Unlikeothermaterialssuchasstructuralsteels,rockshaveaveryinhomogeneousstructure.Asinglerockfragment,togetherwithveryhardinclusions,containsalsorelativelysoftpartsattheboundariesbetweenthehardgrains.Measurementsofthemicrohardnessinanydirectiononapolishedsurfaceofarockfragmentgiveveryscat-teredreadings.Wemayencounterpointswithhardnessgreaterthanthatoftungstencarbide,andafractionofamillimeterawaytheremaybeapointatwhichthehardnessandshearstrengthfallpracticallytozero.AnexarnpleofagraphofthemicrohardnessofarockalongsomedirectionorotherisillustratedinFig.1,curvec.Ifasimilarexperimenttomeasurethemicrohardnesswerecarriedoutwithsteel,weshouldstillfindsomescatterofthereadings,buttheamountofscatter(theratioofthemaximumhardnesstotheminimum)wouldbeseveralordersofmagnitudeless(Fig.1,curved)1.Astudyoftheeffectsofinhomogeneityofrockisthemainprerequisiteforelucidatingthepossibilityofobtainingadurabletool.Astheloadingareaofarockincreases,thereisanincreaseintheprobabilityofthepresenceofweakplacesinthezoneofstrongstresses.Figure2isagraphillustratingthedependenceofthebreakingstressontheareaofcontact.Owingtotheabovefeatures,inrockweobserveadecreaseinthebreakingloadwithincreaseoftheareaofcontact(curvea).Totheleftofpoint0thecurverepresentsthemaximumstrengthoftherock.Formetal,thesamecharacteristicappearsintheformofastraightlinebparalleltotheaxis,andisdeterminedbythefatiguelimitofthemetal.Notethattotherightofpoint0themetalshouldretainitsintegrityunderrepeatedloading,whereasarockshouldbreakafterasingleloadapplication.Evidentlytheworkingzoneliestotherightofpoint0,becauseitisinthiszonethatthemetalisstrongerthantherock.Thetoolwillsometimesfallontoapointwheretherockhashighstrengthandwillthenbesubjectedtomarkedabrasivewear.Iftheenergyofthepercussivedeviceislow,thenfurtherbreakageoftherockwillcease.Itisreasonabletotaketheimpactenergyintheregionof5000-15,000kgm.ResearchattheInstituteofHydrodynamicsoftheSiberianBranchoftheAcademyofSciencesoftheUSSRhasrevealedthatthepossibilityofinflictinghigh-energyblowscompletelyremovesanumberofdifficultieswhichpreventtheadoptionofpercussivebreakingofhardrocksinindustry,whileotherfactorsarisewhichincreasethebreakingefficiency,namely,durabilityofthetoolandasharpreductioninpowerconsumption.In1964someworkersattheInstituteofHydrodynamicsoftheSiberianBranchoftheAcademyofSciencesoftheUSSRputforwardthehypothesis(laterconfirmedbyAmericanworkers)thattheenergyconsumptionofbreak-ingisreducedwhentheimpactenergyisraisedabove5000kg-m.Onthebasisofthishypothesis,workhasbegunoncreatinganinstrumentwithhighimpactenergy.Atthepresenttime,hydraulicandpneumaticdrillsarewidelyusedinindustry.Mostofthesehaveimpactenergiesbelow300kg-m.Onlyinexceptionalcases,forexample,insmashingboulders,doweuserubblehammerswithimpactenergiesof1500kg.m.Hydraulic/pneumatichammersusedatthefaceclearlyhaveinsufficientpowertogiveanyadvantageoverdrillingandblastinginrockbreaking.Thisisbecauseofthehighpowercon-InstituteofHydrodynamics.SiberianBranch,AcademyofSciencesoftheUSSR,Novosiblrsk.TranslatedfromFiziko-TekhnicheskieProblemyRazrabotkiPoleznykhIskopaemykh,No.5,pp.82-89,September-October,1974.OriginalarticlesubmittedMay31,1974.91975PlenumPublishingCorporation,227West17rhStreet,NewYork,N.Y.10011.Nopartofthispublicationmayberepro-duced,storedinaretrievalsystem,ortransmitted,inanyformorbyanymeans,electronic,mechanical,photocopying,micro-filming,recordingorotherwise,withoutwrittenpermissionofthepublisher.Acopyofthisarticleisavailablefromthepublisherfor$15.oo.599e.kg/cmzox-NOIIIF,cm2Fig.1Fig.2Fig,1.IllustrativegraphofmicrohardnessalongXdirection.Curvec:microhardnessofrock;curved:microhardnessofsteel.Fig,2.BreakingstressobvsloadingareaF:a)forrock;b)fortoolmetal.sumpdonandcostofthetoolspercubicmeterofbrokenrock,becausebluntingofthecuttingedgeleadstoces-sationofbreaking.Atthesametime,industryneedspercussivemachinesforcuttingtunnelsinhardrocks,breakinguprockobstaclesinpits,etc.2,3.Forahydraulicdrillwithanimpactenergyabove5000kg.mbluntingofthecuttingedgehaslittleeffectontheefficiencyofrockbreaking.Theseresultswereobtainedwiththeaidofanewlydesignedhydraulicdrill.Indevelopingitwecametotheconclusionthatforpercussivemachineswithimpactenergiesabove5000kg.mitisnecessarytojointhestrikertothetoO1.Thispermitsustoeliminatecollisionbetweenthemasses,tosim-plifythedesign,andtogreatlyincreasetheimpactenergy.Asaresulttheenergypercubicmeterofbrokenrockisreducedto1.15-111oofthatforprevioushydropneumadcdrills.Fromtheexperimentaldataweseethatthemeanspecificenergyconsumptionofbreaking,takenastheratioofthekineticenergyoftheimpactmasstothemeanvolumeofbrokenrockfromoneimpactofenergy4000kg.m,isequalto5kW-h/mS;iftheimpactenergyis12,000kg-m,theenergyconsumptionis2.9kW-h/m3.Inalteringthedesignofthetool,theworkersattheInstituteofHydrodynamicsoftheSiberianBranchoftheAcademyofSciencesoftheUSSRhavetriedtorealizetheprincipleofself-sharpening,inwhichthetoolasitwearskeepsitscrosssectionwhileitsendacquiresasteadyroundedshape.Assuchastrikerwears,itisonlyneces-sarytoadvanceitfromthecollidingmass.Startingin1966,weplannedandbuiltseveralmodificationstothebusinessendsofpercussivemachines.TheyweretestedintheButovskayapitoftheKemerovoregionandmorerecentlyattheTyrnyauzpitoftheKabardino-BalkarASSR,wherethehardnessoftherocksreaches14ontheProtodyakonovscale.Ourdesignforahydraulicdrillwasbasedontheattempttomaximizetheimpactenergywithahighef-ficiency.Thisproblemwassolvedmainlybyusinganenergyaccumulator(airreservoirs),byfeedingenergydirectlyrotheimpactmass,andbyusingfloatingseals.Adifficultyindesign/ngahydraulicdrillwithhighimpactenergyisthenecessityofavoidingthedisruptiveactionofthereboundingrock4-8.TechnicalCharacteristicsofPercussiveDrillHead(HydraulicDrill)Sizeofdrill,m.4.5x0.7x0.7Weightofdrill,kg.4500Weightofmovingparts,kg.1500Impactenergy,kg/m.10,000-15,000Energyconsumption,kW-h/ms.5()e=14)Meanrockspallatlonperimpact,Liters.6-10(f=14)Airchargingpressure,atm.40-50Tenimpactsperminutearepossibleundermanualcontrol.60018I7,516B519104lZI157exk.z;.z././212022;5I4I129/2ZFig.3UnitB/192OFCD2224;3-78/./._.2/k-.-/A-.,J1II-.1.-.)k/.,-?&.-./Fig.4Figure3showsadiagramofthehydraulicdrill.Theimpactmass17issitedwithagapinsideelasticguides16fixedtotheframe,whichisformedfromtubularreceivers4joinedbyfaceplates3(front)and2(back).Insidetheframeisforcecylinder1andthemovingsystemofthepiston,rod,andimpactmass.Therod5hasarticulatedjointsateachend;oneofthese(6)lieswithintheimpactmass,andtheother,thepistonjoint7,iswithinthepistoncup8.Thissystemgivesalldegreesoffreedomanddampingtotheimpactmass.Thepistoncupdividestheforcecylinderintoanaircavity11andawatercavity12.Waterentersthelatterfrompumpsatabovethepressureoftheair.Waterenterscavity12viaannulargap6(Fig.4)formedbytheexternalsurfaceoftheslider13whichclosesport10.Thenpiston8compressesthepneumaticspringanddisplacesairintothereceivers.Aswaterisejectedfromcavity12,thepiston-md-impact-masssystemaccelerates,andtheblowisinflictedontherock.Potentialenergyaccumulatesintheairreceiver.Thelossofenergystoredintheairreceiverischarac-terizedbytheefficiencyofthepneumaticspring,whichisdefinedastheratioofthekineticenergyoftheimpactmassattheendofitsaccelerationtotheworkdoneincompressingthegas:=E/A,whereEmU2max2Assumingthatthegasiscompressedadiabatically,wehavev(Q_,_Vo-),A=Pin1-(1)whereV0=Vr+Vc,mistheweightoftheimpactmass,Umaxisthemaximumvelocityoftheimpactmass,Vristhevolumeoftheairreceiver,Vcisthevolumeoftheaircavityofthecylinderatthemomentwhentheimpact601t,see4.lO-2o5Vr=4.5m/sec/iI.IiI10152025Jo35,04550556os57o75eoc.cmFig.5.Recordofmovementsofimpactmassofhydraulicdrill.Fig.6massreachesthevelocityUreax,andPinistheairpressurebeforethestartofbackwardtraveloftheimpactmass.Equation(1)isonlyapproximate,becauseduringcompressionoftheairpartoftheheatinthereceivertubeshastimetoleakaway.Withanautomaticrecordingde
温馨提示
- 1. 本站所有资源如无特殊说明,都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
- 2. 本站的文档不包含任何第三方提供的附件图纸等,如果需要附件,请联系上传者。文件的所有权益归上传用户所有。
- 3. 本站RAR压缩包中若带图纸,网页内容里面会有图纸预览,若没有图纸预览就没有图纸。
- 4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
- 5. 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,对用户上传分享的文档内容本身不做任何修改或编辑,并不能对任何下载内容负责。
- 6. 下载文件中如有侵权或不适当内容,请与我们联系,我们立即纠正。
- 7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。
最新文档
- 培训采购评审模板
- 预防医学视频课件
- 项目管理课件PMP
- 音乐课件教学课件
- 2025年棉花生产项目建议书
- 2025年气体检测设备项目合作计划书
- 水肌酸产品项目申请报告(参考模板)
- 城市污水管网建设工程资金申请报告(范文)
- 2025年抗血吸虫病药合作协议书
- 无人驾驶技术在物流中的应用
- 《地下工程泥浆施工标准》
- 抛光简介介绍
- 热射病预防与急救
- 初中音乐课件《夏日泛舟海上》
- 采气工班长岗位述职报告
- 呼吸系统课件ppt免费
- 国家开放大学2023年7月期末统一试《42732土地利用规划》试题及答案-开放专科
- 某药业集团产品说明书:加替沙星注射液
- 工艺危险性分析报告
- 消防水箱施工方案 消防水箱的制作要求(6篇)
- 美国范登堡空军基地
评论
0/150
提交评论