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1、Chapter6BasicandSpecialMachining(普通机械加工与特种加工)Lesson23ElectricalDischargeMachiningLesson23ElectricalDischargeMachiningProductApplicationsElectricalDischargeMachiningistheprocessnormallyreferredtoasEDM.Withtheincreasinguseofhard,difficult-to-machinespace-agemetals,EDM'sabilityt
2、omachineburr-free,intricateconfigurations,narrowslots,andblindcavitiesorholesintothesematerials,atclosetolerance,becomesmoreimportant.SinceEDMdoesnotsetupthehighcuttingforcesandmechanicalstrainsoftenassociatedwithconventionalmachining,theprocessiswellsuitedforcuttingtubing,ho
3、neycomb,andotherthin-wall,fragilestructures.Smallholedrilling,0.005in(0.13BACKNEXTLesson23ElectricalDischargeMachiningmm)indiameterandasdeepas20diameters,withvirtuallynobendingordrifting,forexample,ispossible.Forcomparison,inconventionalholedrilling,whenthelengthofatwistdrill
4、is10timestheholediameterorgreater,itisdifficulttoholdstraightness.Slotsasnarrowas0.001in(0.03mm),recesses,reentrantfeatures,holesinawkwardlocations,andevencurvedholesmaybeproducedbythisremarkableprocess.Onewell-establishedapplicationofEDMisinmachiningdiecavitiesandmoldsusedfo
5、rdiecasting,plasticBACKPREVNEXTLesson23ElectricalDischargeMachiningmolding,wiredrawing,extrusion,compacting,cold-heading,andforging.Inthiswidespreadareaofapplication,theEDMprocessisknownas“diesinking.”AnotherimportantapplicationofEDMisinthemetal-formingfieldtoproducepunch,tri
6、m,orstampingdies.Thiscategoryofworkrequiresthatapreciselysizedthroughholebemade,oftenirregularinshape,inasolidcarbidedie.Electricdischargemachiningisideallysuitedtothemanufactureofdiesofthistype,aswellasforprogressiveorcompounddies,whichareacombinationofthroughholeandcavitydi
7、es.BACKPREVNEXTLesson23ElectricalDischargeMachiningAnothervariationofEDMusesawiretravelingfromreeltoreelinsteadofusingashapedtoolfortheelectrode.TheschematicdiagramshowninFig.23-1illustratestheprincipleofamoving-wireelectrodeattachment.Thewireisgraduallyadvancedbetweenthereel
8、stocompensateforthewearthatoccursatthepointofcutting.Thisinnovativev