翻譯部分英文原文AbstractInthispaper,theexperimentalresultsofa45-kWand15-troadheaderexcavatingagallerywithtwodifferenttypesofrockatthefaceusingtwodifferentcuttingheadsareshown.Itisprovedthattheroadheaderworksproperlywithbothcuttingheads.Incomparisonwithotherresultsintheliterature,theprincipalparameters,i.e.specificenergy,cuttingrateandtoolwear,areatalevelthatcanbeconsideredsatisfactorytakingintoaccountthelowpoweroftheroadheader.Ontheotherhand,theinfluenceofthenumberofpicks,whichisthemaindifferencebetweenthetwocuttingheads,ontheoperationalparametersisshown.2003ElsevierScienceLtd.Allrightsreserved.Keywords:Roadheaders；Cuttingheaddesign；Specificcuttingenergy；Cuttingrate；Toolwear1.Introduction:experienceinusingofroadheadersinamineThecoalbasinintheNWofSpain(Arecesetal.,1994)formsasynclineinwhichthecoalseamsaremoderatelyinclined(30358)attheNWfoldaxisandalmostvertical(70908)attheSEfoldaxis.CarboniferousmaterialoccursunderaflatPermianoverburden,150mthick.Theuseofroadheadersinthisminewasaconsequenceofmechanisationofthework.Coalminingbythelong-wallmethodwithpoweredroofsupportsmakesrapidadvanceoftheaccessroadsnecessary.Ontheotherhand,thetwoalternativesforminingverythickcoalseams,i.e.room-and-pillarinflatseamsandsublevelcavinginverticalseams,alsomakestheuseofroadheaderdrivinggalleriesinthecoalseamsnecessarySeveraltypesofroadheadersareusedinthemineforthesedifferentworks:a.Oneroadheader(Fig.1)of60tinweight,witha250-kWrippingcuttinghead,especiallydesignedforthistypeofmineinthecontextofresearchproject(Anon.,1991；Toranoetal.,1992；Torano,1994)withtheobjectiveofdrivinggalleriesof10-mcross-2sectionsincoalseamsof1.01.5minthickness(withapprox.50%ofthesectioninhardrockofuniaxialcompressivestrengthuptosc120MPa)；b.Tworoadheaders(Fig.2)of24tinweight,witha110-kWrippingcuttingheadmainlyusedindrivinggallerieswithmediumhardrock(c60MPa)orincroom-and-pillarmining；c.Tworoadheaders(Fig.3)of12.5tinweightwithamillingcuttingheadof45kW,onlyusedinadvancingofgalleriesincoal(softrock)；theconveyortypemeanstheroadheaderhasa2.8-mwidthandbecauseofthisitcanonlybeusedforadvancinggalleriesincoalseamsof3.0minthickness(mainlyintheminingmethodtermedsublevelcaving)；andd.Oneroadheader(Fig.4)of15.5tinweightwitha45-kWmilling-typecuttinghead,developedwiththisnarrowdesignespeciallyforthismine(Toranoetal.,1997)foritsapplicationindrivinggalleriesin2.0-m-thickcoalseams(minimum1.70m)inwhichpreviousroadheaderscouldnotbeused.Thestudydescribedherewascarriedoutinthecontextofthisproject.Duringtheadvanceofgalleriesin2.0-m-thickcoalseams,itwassometimesnecessarytoexcavatetherockoftheseamwalls,thestrengthofwhichwasalmostoverthelimitofthecuttingcapacityoftheroadheader.Itwasdecidedtoinvestigateif,undertheseconditions,theoperationorcuttingparameterswereacceptableusingtwodifferentcuttingheadsinthetest.2.Testdescription2.1.TestobjectivesTheaimwastodeterminethepossibilityofdrivingthesegalleriesbymeansofa45-kWroadheader,comparingtwodifferentcuttingheadsexcavatingthesametypeofrockinsimilaroperatingcycles.Themaindifferencebetweenthetwocuttingheadswasthenumberofpicks:thefirstcuttingheadhad36picks,whilethenewonehadonly24(Fig.5).Becauseofthelowernumberofcuttingtoolsincontactwiththerock,thetorquetransmittedbythemotorwastransformedtoalargertangentialforceinthepick,whichallowshigher-strengthrocktobecut.Stressconcentrationisthemajorfactorinrockfragmentation.Theparameterstomeasure(accordingtoclassicstudiesonthistheme；FowellandMcFeat-Smith,1976；Gehring,1989)arethecuttingrate(volumeofrockexcavatedpertimeunitinm3/s),specificenergy(ener-3gynecessarytoexcavateaunitofvolumeinMJ/m3)3andthetoolwearorspecificpickconsump