MSE#440/540:#Processing#of#Metallic#Materials
Instructors:)Yuntian)Zhu Office:)308)RBII Ph:)513D0559 [email protected]
Lecture)9:)Forging
Department)of)Materials)Science)and)Engineering 1 NC#State#University Forging
Deformation-process-in-which-work-is-compressed- between-two-dies-- • Oldest-of-the-metal-forming-operations – Dates-from-about 5000-B-C- • Products:-engine-crankshafts,-connecting-rods,-gears,- aircraft-structural-components,-jet-engine-turbine-parts-- – Also,-basic-metals-industries-use-forging-to-establish-basic- shape-of-large-parts-that-are-subsequently-machined-to-final- geometry-and-size---
http://www.youtube.com/watch?v=Fa0FVYxbVWk (Axe,-5.5-min)
NC#State#University Classification+of+Forging+Operations
• Cold+vs.+hot+forging:++ – Hot+or+warm+forging+– advantage:+reduction+in++ strength+and+increase+in+ductility+of+work+metal++ – Cold+forging+– advantage:+increased+strength+due+ to+strain+hardening+ • Impact+vs.+press+forging: – Forge+hammer+@ applies+an+impact+force+ – Forge+press+@ applies+gradual+force+
NC#State#University Types&of&Forging&Operations
• Open2die&forging&2 work&is&compressed&between&two& flat&dies,&allowing&metal&to&flow&laterally&with&minimum& constraint • Impression2die&forging&2 die&contains&cavity&or& impression&that&is&imparted&to&workpart – Metal&flow&is&constrained&so&that&flash&is&created& • Flashless&forging&(closed&die&forging)&2 workpart&is& completely&constrained&in&die
NC#State#University Open%Die(Forging(
Compression(of(workpart(between(two(flat( dies(( – Deformation(operation(reduces(height(and( increases(diameter(of(work(( – Also(called(upsetting or(upset)forging)(decrease( in(height,(increase(in(diameter)
https://mail.google.com/mail/u/0/?shva=1#inbox/15ee3788482e1e36?projector=1 (Autoparts,(3(min)(
NC#State#University Open>Die%Forging%with%No%Friction
• (1)%Start%of%process%with%workpiece%at%its%original%length% and%diameter,%(2)%partial%compression,%and%(3)%final%size
ho True%strain:% ! = ln h
Quiz:%What%is%engineering%strain? NC#State#University Open4Die'Forging'with'Friction
Actual'deformation'of'a'cylindrical'workpart'in'open4die' forging,'showing'pronounced'barreling:'(1)'start'of' process,'(2)'partial'deformation,'and'(3)'final'shape
!.!!" ! ! ! = ! ! ! , ! = 1 + , ! = ! !! = ! ℎ ! ! ! ! ! ! ! ! ! !
NC#State#University Impression*Die,Forging
Compression,of,workpart,by,dies • Flash,is,formed,by,metal,that,flows,beyond,die,cavity, into,small,gap,between,die,plates, • Flash,must,be,later,trimmed,,but,it,serves,an,important, function,during,compression: – As,flash,forms,,friction,resists,continued,metal,flow,into,gap,, constraining,metal,to,fill,die,cavity,,
NC#State#University Impression*Die,Forging,Practice
• Several,forming,steps,are,often,required – With,separate,die,cavities,for,each,step,, • Beginning,steps,redistribute,metal,for,more, uniform,deformation,and,desired,metallurgical, structure,in,subsequent,steps, • Final,steps,bring,the,part,to,final,geometry,,
http://www.youtube.com/watch?v=mySkT0Gw_X0 (1,min),
NC#State#University Advantages*and*Limitations*of* Impression3Die*Forging • Advantages*compared*to*machining*from*solid*stock: – Higher*production*rates – Less*waste*of*metal – Greater*strength – Favorable*grain*orientation*in*the*metal • Limitations: – Not*capable*of*close*tolerances – Machining*is*often*required*to*achieve*accuracies*and* features*needed
Quiz:*why*forging*improve*the*strength?
NC#State#University Flashless'(closed'die)'Forging
Compression'of'work'in'punch'and'die'tooling'whose' cavity'does'not'allow'for'flash • Starting'work'volume'must'equal'die'cavity'volume' within'very'close'tolerance'' • Process'control'more'demanding'than' impression?die'forging'' • Best'suited'to'part'geometries'that'are'simple'and' symmetrical'' • Often'classified'as'a'precision)forging process
NC#State#University Flashless%Forging%(Closed%Die%Forging)
• (1)%Just%before%contact%with%workpiece,%(2)% partial%compression,%and%(3)%final%punch%and% die%closure
NC#State#University Upset'Forging
• Upset'forging'to'form'a'head'on'a'bolt'or'similar' hardware'item:'(1)'wire'stock'is'fed'to'stop,'(2)'gripping' dies'close'on'stock'and'stop'retracts,'(3)'punch'moves' forward,'(4)'bottoms'to'form'the'head
NC#State#University Heading*(Upset*Forging)
• Examples*of*heading*operations:*(a)**heading*a*nail*using* open*dies,*(b)*round*head*formed*by*punch,*(c)*and*(d)*two* common*head*styles*for*screws*formed*by*die,*(e)*carriage* bolt*head*formed*by*punch*and*die
NC#State#University Swaging'
Accomplished'by'rotating'dies'that' hammer'a'workpiece'radially'inward'to' taper'it'as'the'piece'is'fed'into'the'dies'' • Used'to'reduce'diameter'of'tube'or'solid' rod'stock • Mandrel'sometimes'required'to'control' shape'and'size'of'internal'diameter'of' tubular'parts''
NC#State#University Swaging(and(Radial(Forging
• Swaging(process(to(reduce(solid(rod(stock4(dies(rotate(as(they( hammer(the(work(( • In(radial(forging,(workpiece(rotates(while(dies(remain(in(a(fixed( orientation(as(they(hammer(the(work((
https://www.youtube.com/watch?v=LFly3VRqjiE (cartoon,(1.12( min)
NC#State#University HW#assignment
• Reading#assignment:#Chapters#13
• Review#Questions:#13.10,#13.11,#13.12,# 13.14,# • Problems:#13.10,#13.12,#13.14
Department#of#Materials#Science#and#Engineering 17 NC#State#University