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1、ForgingofMetalsIntroductionForgingisanimportanthot-formingprocess.Itisusedinproducingcomponentsofallshapesandsizes,fromquitesmallitemstolargeunitsweighingseveraltons.Forgingistheprocessbywhichmetalisheatedandisshapedbyplasticdeformationbysuitablyapplyingcompressiveforce.Handforgi
2、ngtoolscomprisevariouslyshapedhammers.Thebaseonwhichtheworkissupportedduringforgingistheanvil.Forthesemimechanizedforgingofsmalltomedium-sizedcomponents,forginghammerspoweredbyvariousmeansareemployed.Thefeaturecommontoallofthemisthat,likethehandforginghammer,theyutilizetheenergyo
3、fafallingweighttodevelopthepressureneededforshapingthemetal.Largercomponentsareforgedbymeansofforgingpressesoperatedbysteamorcompressedairorbyhydraulicorelectricpower.Largelyautomaticforgingmachinesareusedforthequantityproductionofengineeringparts.Adistinctionmaybemadebetweenopen
4、-dieforging,usuallyintheformofhammerforging,andclosed-dieforging.Inhammerforging,thecomponentisshapedbyhammerblowsaidedbyrelativelysimpletools.Thesemayincludeopendiesi.e.,diesthatdonotcompletelyenclosethemetaltobeshaped.Oneofthebasicoperationsofhammerforgingistheelongationofapiec
5、eofmetalbystretchingwithhammerblows,causingittobecomethinnerandlonger.Inhandforgingthework-pieceisusuallyturned90°aftereachblow,inordertoforgeitthoroughlyandpreventitslateralexpansion.Theoppositeofelongationisupsetting,whichproducescompressiveshortening.Forexample,thediameterofab
6、arcanbeincreasedbyheatingandhammeringaxially.Moreimportantisclosed-dieforging,verywidelyusedformassproductioninindustry,inwhichthemetalisshapedbypressingbetweenapairofforgingdies.Theupperdieisusuallyattachedtotheramofaforgingpressoraforginghammer,whilethelowerdieisstationary.Toge
7、thertheyformacloseddie.Closed-dieforgingcanproducecomponentsofgreatercomplexityandaccuracy,withabettersurfacefinishthanthemoretraditionalmethodsnotusingcloseddies.Thediesaremadeofspecialheat-resistantandwear-resistanttoolsteels.Apieceofhotmetalsufficienttoslightlyoverfillthediesh
8、apeisplacedinthebottomdie,andthetopdieis
