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外文翻译--采矿作业的机械化及自动化采石挖掘机工作装置的模型 英文版.pdf

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外文翻译--采矿作业的机械化及自动化采石挖掘机工作装置的模型 英文版.pdf

MECHANIZATIONANDAUTOMATIONOFMININGOPERATIONSAMODELOFTHEWORKINGOPERATIONSOFAQUARRYEXCAVATORE.V.Gaisler,A.P.Mattis,E.A.Mochalov,andS.V.ShishaevWedevelopamethematicalmodeloftheprocessofopenpitminingwithaquarryexcavatorusingabucketthathasactivebladesdrivenbyimpactblocksinstalledinthefrontwall.Thebucketoperatesasfollows.Whenthebucketcomesincontactwitharockareathatcanbebrokenbyaforcegreaterthanthesumoftheforcesoffrictionofthetoolonthesleeveandtheforceofactivationofthestartingdevice,theimpactblocksareenergized.TheactionoftheseblockscausesthebucketbladestoentertherocktoadepthX,weakeningthezonelocateddirectlyunderthebladesandformingthesocalleddisruptedbondingzone\i\.Thiszonerequiresmuchlessforcetobebrokenthananintactmass.Withsuchactivebuckets,strongrockscanbeexcavatedwithoutpreloosening.Themainparametersdescribingthemovementsofthebucketduringexcavationincludethemechanicalpropertiesoftherock,thevariationofthesepropertiesundertheeffectoftheimpact,theworkingcharacteristicsofthedrivesoftheactuatormechanisms,andtheparametersoftheequipment.Twotypesofdestructiontakeplaceduringthecourseofexcavationcuttingandimpactbreaking.Thegeometricsumofforcesactingonallthefacesofabladerepresentstheresistancetointrusion.TheprojectionofthissumontotheaxisoftheimpactblockisPltheprojectionontothedirectionperpendiculartotheaxisisP2.Thesumofforcesactingperpendicularlytothebuckettravelingplaneisequaltozerobecauseblockfracturingismainlyperformed.Thefollowingassumptionsaremadeforamathematicalmodeldescribingthemotionsofthebucketthecenterofmassoftherockinthebucketisstationaryrelativetothebucketchipsareseparatedcontinuouslytheloadsonthebucketbladesareequalthebladespenetratetherockinstantaneouslyuponimpacttheresistancetothebucketfillingisdisregardedthemomentoffrictionrelativetotherotationaxisofthearmisdisregarded.Withtheseassumptions,themotionofthebucketcanbeinterpretedasthemotionofatwodimensionalmechanismundertheeffectofexternalforces,whichincludestheforcedevelopedbythedrivesofthepressuremechanismandtheliftmechanism,thegravityforce,andtheresistanceforceoftherockface.Thepositionofthebucketateachpointintimeisdefinedbythecoordinatert,thedistanceOC,andttheanglebetweentheboomandthebucketstick.Thekineticenergyofthismechanismisexpressedasm,JT1wherem1istherockmassandthebucketm2isthemassofthestickandtheemptybucketJisthemomentofinertiaofthebucketwithrockandthestickrelativetoitsrotationaxisInstituteofMining,SiberianBranch,AcademyofSciencesoftheUSSR,Novosibirsk.TranslatedfromFizikoTekhnicheskieProblemyRazrabotkiPoeznykhIskopaemykh,No.2,pp.6067,MarchApril,1991.Originalarticle.submittedSeptember25,1990.00385581/91/27020131512.5091992PlenumPublishingCorporation131YmlrlCBiiJmirrl2IGA\,2whereJ1isthemomentofinertiaofanemptybucketandthestickrelativetothecenterofmassandrrlisthecoordinateofthecenterofmassoftheemptybucketwiththestick.Therockmassinthebucketmdependsonthepathtraveledbythefrontedgeofthebucketandtheinitialshapeoftherockface.Inordertowriteanexpressionfortherateofmassincrement,wewillconsidertheschemeinFig.2.Supposethatthepathtraveledbythebucketedgebythetimetisdescribedbythecurvef2r2,2Theinitialshapeofthefacebythecurvef3r3,3,wherer2,,r3,3arepolarcoordinateswiththeoriginatzero.DuringthetimedtthebucketedgetravelsadistanceICDIinthatcase,sinced2d3themassincrementwithinthetimedtisspecifiedbyIdmT,BIOClIODIIOA\.IOBIsinda2,where0istherockdensityandBisthewidthofthebucketedge.Weseefromthediagramthatlocir,ION{r§dr,IOAIr,IOBIr§dr3.Consideringthatsindada2anddisregardingthesquaresoftheinfinitesimalvariables,wewrite1a,,,,r,z,da.Theincrementd2isequaltotheproductattheangularspeedofthestickatthetimetandtheincrementdt,i.e.,d2da3dt.TherateofincrementofthemassisnowexpressedasdNlo,.7_,id,.,.3Themassfallingintothebucketduringthetimetisdefinedbym,JsdT0ThismassmIisonlyafunctionofthetimet.MakinguseofthefundamentalequationofthedynamicsofavariablemasspointMeshcherskiisequation,wecandemonstratethatLagrangianequationsareapplicabletothemechanicalsystemthatconsistsofvariablemassmaterialpointsiftheabsolutevelocityoftheassociatedmassisequaltozero.Consideramechanicalsystemcomprisedofnmaterialpointswithmassesml,m2.....mi,...,mn,thatmovewithvelocitiesvi.Lagrangianequationsformiconsthavebeenderivedin\2,p.340\.Considerthecaseofmimit.Infollowing\2\,weintroducegeneralizedcoordinatesq,suchthatiriql,q2,,qs,t,whereriisthepositionvectoroftheithmass.Now,i1j,OliOijIuqjUqjOqwherejisgeneralizedvelocity.Thekineticenergyofthemechanicalsystematanytimepointisdefinedas1TniViUi.WefindpartialderivativesofkineticenergywithrespecttothegeneralizedcoordinateqjandthegeneralizedvelocityjoroiaqjmiUir,ilaqi132_ih,iOriOTmivlmiviOqji1Oqji\OqjWedifferentiatethisexpressionwithrespecttotime.Considernowthefirstsum,takingintoaccountthefundamentalequationofthedynamicsofvariablemasspointforthecasewheretheabsolutevelocityoftheassociatedmassisequaltozero\2,p.143\,amvF,m.7wherePistheresultantoftheforcesappliedtothepoint.Foranonfreematerialpointwithvariablemass,wehaveelT,idmml77dfviF.,7,whereRiistheresultantofthereactionsofconstraintsappliedtotheithpoint.Now,7,,m,.,,,7,,7,,i1S.OriFnQ.ilThesecondsumis,infact,8T/Sqj\2,p.342\.WeobtaindtQjoOTOqForasystemwithstationaryperfectconstraintsQjR0dOT07ItistheLagrangianequationforamechanicalsystemconsistingofvariablemassmaterialpointsundertheassumptionthattheabsolutevelocityoftheassociatedmassisequaltozero.Aswesee,itisidenticaltoaLagrangianequationderivedforaconstantmassofmaterialpointsbelongingtothemechanicalsystem.TheLagrangianmotionequationsforthismechanismareru7QJ7,,A,Q5whereQI,Q2aregeneralizedforcesactingondisplacements6rand6,respectively,lQ,,,,o,/,o.,/o,,,.oImm.gcos,O,l.r.sinOCDrICDI/\.P..sincosnOCD/6133Fig.1Fig.i.Fig.2.CDFig.2Designschemeforanexcavatorwithanactivebucket.Evaluationoftheincrementofrockweightinthebucket.,,iocl/\11..,.sin.I,.tCEI.,sinmxgsin2gsin.,rlmj.ICBImelCAIgc,where88r,aistheanglebetweenthedirectionsoftheforcesFIandFwhicharegeneratedbythedrivesofthepressuremechanismandliftmechanism,respectively.Thecharacteristicsofthedrivesofthepressureandliftmechanismsoftheexcavatorestablishtherelationshipbetweenthemomentofforcesonthemotorshaftsandtherotationvelocities,soF,/,.,/,.7Theformofthefunctionsf1andf2,dependsonthecharacteristicsofthedrivesandthegearratiosofthepressureandliftmechanisms.TheexpressionforQlandQ2includestheforcesPlandP2theyarethecomponentsoftheresistancetodigging.TheycanbeestimatedwiththeaidofthemathematicallogicmodelsofDombrovskii,Zelenin,Vetrov,Artemev,Balovnev,orFedorov\3\.Generally,theresistancetodiggingdependsonthemechanicalpropertiesofthebed,thetoolgeometry,thecuttingangle2,andthethicknessofthelayercuth.WeshouldconsiderthatthelasttwoparametersdependimplicitlyOntimesinOCOqa|csin,a,,7,arcsin1trr.r71,rCD\22rlCDIcosOCDhlar2rAftercomputingthederivativesofthekineticenergyandsubstitutingthemintotheLagrangianequations,wehaverotm2rmlrmlrm2rr,,a2Qi,8whereQIandQ2aredefinedby6.ThemotionofthismechanismisdescribedbyEqs.8.TheinitialconditionsoftheseequationsaremOO,00,,00,0o,rOro.9134

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