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1、Unit13TheFormingandMoldingEquipmentLesson27TypesofPress13.1Lesson28TheInjection-moldingMachine13.2Lesson29TheSpecificationsofPress13.3ReadingMaterials27MainComponentsofaPress13.4Unit13TheFormingandMoldingEquipmentReadingMaterials28ComponentsofInjection-moldingMachine13.5ReadingMaterials29TheSpe
2、cificationsofInjection-moldingMachine13.613.1Lesson27TypesofPressFortheapplications,therearemanytypesofthepresses,suchasthesingle-actionstraight-slideeccentricmechanicalpress,punchpress,hydro-formerpress,hydraulicpress,pressbrake,triple-actionpress,turretpress,two-pointpress,twin-drivepress,two
3、-pointsingle-actionpress,watchpress,trimmingpress,closed-typesingle-actioncrankpress,knuckle-leverpress,one-pointsingle-actionpress,open-backinclinablepress,open-sidepress,four-pointpress,four-crankpress,flywheel-typescrewpress,frictionscrewpress,straight-sidesingle-actiondouble-crankpress,rock
4、er-armpress,screwpressandtop-drivesheet-metalstampingautomaticpressandsoon.Adouble-actionpressisusedforlarge,ordeepdrawingoperationsonsheetmetalparts．Thistypeofpresshasanouterram(blankholder)andasectioninnerram(punchholder).Duringtheoperatingcycle,theblankholdercontactsthematerialfirstandapplie
5、spressuretoallowthepunchholdertoproperlydrawthepart(Figure13-1).Atriple-actionpresshasthesameinnerandouterramasthedouble-actionpress,butathirdraminthepressbedmovesupallowingareversedrawtobemadeinonepresscycle[1].Thetriple-actionpressisnotwidelyused．Aknucklepressisusedforcoiningoperation.Thedesi
6、gnofthedriveallowsforveryhighpressuresatthebottomoftheramstroke.Thistypeusesacrank,whichmovesajointconsistingoftwoleversthatoscillatetoandfromthedeadcenterandresultsinashort,powerfulmovementoftheslidewithslowtravelnearthebottomofthestroke．Ahydraulicpressisusedbasicallyforformingoperationsandhas
7、asloweroperatingcycletimethanmostmechanicalpresses.Theadvantagesofhydraulicpressesarethattheworkingpressure,stroke,andspeedoftheramareadjustable(Figure13-2).Hydraulicpressesbelongtotheforce-constrainedtypeofformingmachines.Theirma
