to ach ieve certain u sefu l p rop erties. Su ch p rocesses in clu d e h eat treat- m en t p rocesses su ch as h ard en in g or recrystallization an n ealin g.
Form ing – as t h e t ech n o lo gy fo rm in g t h e cen t ral su bject m at t er o f t h is bo o k – is d efin ed by DIN 8580 as m an u fact u rin g t h ro u gh t h e t h ree-
d im en sio n al o r p last ic m o d ificat io n o f a sh ap e wh ile ret ain in g it s m ass an d m at erial co h esio n . In co n t rast t o d efo rm at io n , fo rm in g is t h e m o d -
ificat io n o f a sh ap e wit h co n t ro lled geo m et ry. Fo rm in g p ro cesses are cat ego rized as ch ip less o r n o n -m at erial rem o val p ro cesses.
In p ract ice, t h e field o f “fo rm in g t ech n o lo gy” in clu d es n o t o n ly t h e m ain cat ego ry o f fo rm in g bu t also su bt o p ics, t h e m o st im p o rt an t o f
wh ich are dividing an d joining through form i ng
Fig. 2.1.2 . Co m bin at io n s
wit h o t h er m an u fact u rin g p ro cesses su ch as laser m ach in in g o r cast in g are also u sed .
2.1.2 Forming
Fo rm in g t ech n iq u es are classified in acco rd an ce wit h DIN 8582 d ep en d in g o n t h e m ain d irect io n o f ap p lied st ress
Fig. 2.1.3 :
– fo rm in g u n d er co m p ressive co n d it io n s, – fo rm in g u n d er co m bin ed t en sile an d co m p ressive co n d it io n s,
– fo rm in g u n d er t en sile co n d it io n s, – fo rm in g by ben d in g,
– fo rm in g u n d er sh ear co n d it io n s.
6
Basic principles of metal forming
fo rm
in g
un de
r c om
pr es
si ve
co nd
iti on
s fo
rm in
g un
de r s
he ar
c on
di tio
ns
fo rm
in g
un de
r c om
pr es
si ve
an d
te ns
ile c
on di
tio ns
fo rm
in g
un de
r t en
si le
c on
di tio
ns
forming parting
joining
fo rm
in g
by be
nd in
g
jo in
in g
th ro
ug h
fo rm
in g
di vi
di ng
Fig. 2.1.2 Production
processes used in
the field of forming
technology
Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998
Th e DIN st an d ard d ifferen t iat es bet ween 17 d ist in ct fo rm in g p ro cesses acco rd in g t o t h e relat ive m o vem en t bet ween d ie an d wo rkp iece, d ie
geo m et ry an d wo rkp iece geo m et ry Fig. 2.1.3
. Form ing under com pressive conditions
Cast slabs, ro d s an d billet s are fu rt h er p ro cessed t o sem i-fin ish ed p ro d - u ct s by rolling. In o rd er t o keep t h e req u ired ro llin g fo rces t o a m in i-
m u m , fo rm in g is p erfo rm ed in it ially at h o t fo rm in g t em p erat u re. At t h ese t em p erat u res, t h e m at erial h as a m alleable, p ast e-like an d easily
fo rm able co n sist en cy wh ich p erm it s a h igh d egree o f d efo rm at io n wit h o u t p erm an en t wo rk h ard en in g o f t h e m at erial. Ho t fo rm in g can
be u sed t o p ro d u ce flat m at erial o f t h e t yp e req u ired fo r t h e p ro d u ct io n o f sh eet o r p lat e, bu t also fo r t h e p ro d u ct io n o f p ip e, wire o r p ro files. If
t h e t h ickn ess o f ro lled m at erial is belo w a cert ain m in im u m valu e, an d wh ere p art icu larly st rin gen t d em an d s are im p o sed o n d im en sio n al ac-
cu racy an d su rface q u alit y, p ro cessin g is p erfo rm ed at ro o m t em p era- t u re by co ld ro llin g. In ad d it io n t o ro llin g sem i-fin ish ed p ro d u ct s, su ch
as sh eet an d p lat e, gears an d t h read s o n d iscret e p art s are also ro lled u n d er co m p ressive st ress co n d it io n s.
Open die form ing is t h e t erm u sed fo r co m p ressive fo rm in g u sin g t o o ls wh ich m o ve t o ward s each o t h er an d wh ich co n fo rm eit h er n o t at all o r
o n ly p art ially t o t h e sh ap e o f t h e wo rkp iece. Th e sh ap e o f t h e wo rk- p iece is creat ed by t h e execu t io n o f a free o r d efin ed relat ive m o vem en t
7
M ethods of forming and cutting technology
forming under compres- sive conditions DIN 8583
forming under compres- sive and tensile
conditions DIN 8584 forming under
tensile conditions DIN 8585
forming under shearing conditions DIN 8587
forming by bending DIN 8586
forming
ro lli
ng op
en d
ie fo
rm in
g
cl os
ed d
ie fo
rm in
g
co in
in g
st rip
pi ng
de ep
d ra
w in
g fla
ng in
g sp
in ni
ng w
rin kl
e bu
lg in
g ex
te nd
in g
by s
tr et
ch in
g
ex pa
nd in
g di
sp la
ce m
en t
tw is
tin g
st re
tc h
fo rm
in g
be nd
in g
w ith
li ne
ar
di e
m ov
em en
t be
nd in
g w
ith ro
ta ry
di e
m ov
em en
t
fo rm
in g
by fo
rc in
g th
ro ug
h
an o
rif ic
e
Fig. 2.1.3
Classification of production processes used in forming in accordance w ith DIN 8582
Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998
bet ween t h e wo rkp iece an d t o o l sim ilar t o t h at u sed in t h e h am m er fo rgin g p ro cess
Fig. 2.1.4 .
Closed die form ing is a co m p ressive fo rm in g p ro cess, wh ere sh ap ed t o o ls d ies m o ve t o ward s each o t h er, wh ereby t h e d ie co n t ain s t h e
wo rkp iece eit h er co m p let ely o r t o a co n sid erable ext en t t o creat e t h e fin al sh ap e
Fig. 2.1.5 .
Coining is co m p ressive fo rm in g u sin g a d ie wh ich lo cally p en et rat es a wo rkp iece. A m ajo r ap p licat io n wh ere t h e co in in g p ro cess is u sed is in
m an u fact u rin g o f co in s an d m ed allio n s Fig. 2.1.6
. Form ing by forcing through an orifice is a form in g tech n iq u e wh ich
in volves th e com p lete or p artial p ressin g of a m aterial th rou gh a form in g d ie o rifice t o o bt ain a red u ced cro ss-sect io n o r d iam et er. Th is t ech n iq u e
in clu d es t h e su bcat ego ries free extrusion, extrusion of sem i-finished prod- ucts and extrusion of com ponents cf.
Sect . 6.1 .
8
Basic principles of metal forming die
w orkpiece
Fig. 2.1.4
Open die forming
upper die w orkpiece
low er die
Fig. 2.1.5
Closed die forming
Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998
Du rin g free extrusion, a billet is p art ially red u ced wit h o u t u p set t in g o r bu lgin g o f t h e n o n -fo rm ed p o rt io n o f t h e wo rkp iece
Fig. 2.1.7 an d
cf. Sect . 6.5.4
. Free ext ru sio n o f h o llo w bo d ies o r t ap erin g by free ext ru - sio n in vo lves p art ial red u ct io n o f t h e d iam et er o f a h o llo w bo d y, fo r
exam p le a cu p , a can o r p ip e, wh ereby an ext ru sio n co n t ain er m ay be req u ired d ep en d in g o n t h e wall t h ickn ess.
In extrusion of sem i-finished products a h eat ed billet is p laced in a co n - t ain er an d p u sh ed t h ro u gh a d ie o p en in g t o p ro d u ce so lid o r h o llo w
ext ru sio n s o f d esired cro ss-sect io n . Cold extrusion of discrete parts in vo lves fo rm in g a wo rkp iece lo cat -
ed bet ween sect io n s o f a d ie, fo r exam p le a billet o r sh eet blan k cf. Sect s. 6.5.1
t o 6.5.3
an d 6.5.7
. In co n t rast t o free ext ru sio n , larger d efo rm at io n s are p o ssible u sin g t h e ext ru sio n m et h o d .
9
M ethods of forming and cutting technology
embossing punch
w orkpiece
Fig. 2.1.6
Coining
punch
w orkpiece press bush
Fig. 2.1.7 Free extrusion
of shafts
Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998
Ext ru sio n is u sed fo r t h e m an u fact u re o f sem i-fin ish ed it em s su ch as lo n g p ro files wit h co n st an t cro ss sect io n s. Co ld ext ru sio n is u sed t o p ro -
d u ce in d ivid u al co m p o n en t s, e. g. gears o r sh aft s. In bo t h m et h o d s, fo rm in g t akes p lace u sin g eit h er rigid d ies o r act ive m ed ia. In ad d it io n ,
a d ifferen ce is d rawn d ep en d in g o n t h e d irect io n o f m at erial flo w re- lat ive t o t h e p u n ch m o vem en t – i. e. fo rward s, backward s o r lat eral –
an d t h e m an u fact u re o f so lid o r h o llo w sh ap es cf. Fig. 6.1.1
. Based o n t h e co m bin at io n o f t h ese d ifferen t iat in g feat u res, in acco rd an ce wit h
DIN 8583 6 a t o t al o f 17 p ro cesses exist fo r ext ru sio n . An exam p le o f a m an u fact u rin g m et h o d fo r can s o r cu p s m ad e fro m a so lid billet is back-
ward cu p ext ru sio n Fig. 2.1.8
. Form ing under com bination of tensile and com pressive conditions
Drawing is carried o u t u n d er t en sile an d co m p ressive co n d it io n s an d in vo lves d rawin g a lo n g wo rkp iece t h ro u gh a red u ced d ie o p en in g. Th e
m o st sign ifican t su bcat ego ry o f d rawin g is strip drawing. Th is in vo lves d rawin g t h e wo rkp iece t h ro u gh a clo sed d rawin g t o o l d rawin g d ie,
lo wer d ie wh ich is fixed in d rawin g d irect io n . Th is allo ws t h e m an u - fact u re o f bo t h so lid an d h o llo w sh ap es. In ad d it io n t o t h e m an u fact u re
o f sem i-fin ish ed p ro d u ct s su ch as wires an d p ip es, t h is m et h o d also p erm it s t h e p ro d u ct io n o f d iscret e co m p o n en t s. Th is p ro cess in vo lves
red u cin g t h e wall t h ickn ess o f d eep -d rawn o r ext ru d ed h o llo w cu p s by iro n in g, an d h as t h e effect o f m in im izin g t h e m at erial in p u t , p art icu -
larly fo r p ressu re co n t ain ers, wit h o u t alt erin g t h e d im en sio n s o f t h e can bo t t o m
Fig. 2.1.9 an d cf.
Sect . 6.5.5 .
10
Basic principles of metal forming punch
w orkpiece press bush
blank
ejector
Fig. 2.1.8 Backw ard
can extrusion
Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998
Deep drawing is a m et h o d o f fo rm in g u n d er co m p ressive an d t en sile co n d it io n s wh ereby a sh eet m et al blan k is t ran sfo rm ed in t o a h o llo w
cu p , o r a h o llo w cu p is t ran sfo rm ed in t o a sim ilar p art o f sm aller d im en - sion s with ou t an y in ten tion of alterin g th e sh eet th ickn ess cf.
Sect. 4.2.1 .
Usin g t h e single-draw deep drawing technique it is p o ssible t o p ro d u ce a d rawn p art fro m a blan k wit h a sin gle wo rkin g st ro ke o f t h e p ress
Fig. 2.1.10 .
In case o f large d efo rm at io n s, t h e fo rm in g p ro cess is p erfo rm ed by m eans of redrawing, gen erally u sin g a n u m ber o f d rawin g o p erat io n s.
Th is can be p erfo rm ed in t h e sam e d irect io n by m ean s o f a t elesco p ic p u n ch
Fig. 2.1.11 o r by m eans of reverse drawing, wh ich in vo lves t h e
seco n d p u n ch act in g in o p p o sit e d irect io n t o t h e p u n ch m o t io n o f t h e p revio u s d eep -d rawin g o p erat io n
Fig. 2.1.12 .
11
M ethods of forming and cutting technology
punch
w orkpiece
sinking die
Fig. 2.1.9
Can ironing
punch blank holder
blank draw n part
die
Fig. 2.1.10
Single-draw deep draw ing w ith blank holder
Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998
Th e m o st sign ifican t variat io n o f d eep d rawin g is d o n e wit h a rigid t o o l
Fig. 2.1.10 . Th is co m p rises a p u n ch , a bo t t o m d ie an d a blan k
h o ld er, wh ich is in t en d ed t o p reven t t h e fo rm at io n o f wrin kles as t h e m et al is d rawn in t o t h e d ie. In sp ecial cases, t h e p u n ch o r d ie can also
be fro m a so ft m at erial. Th ere are d eep d rawin g m et h o d s wh ich m ake u se o f act ive m ed ia
an d act ive en ergy. Deep d rawin g u sin g act ive m ed ia is t h e d rawin g o f a blan k o r h o llo w bo d y in t o a rigid d ie t h ro u gh t h e act io n o f a m ed iu m .
Act ive m ed ia in clu d e fo rm less so lid su bst an ces su ch as san d o r st eel balls, flu id s o il, wat er an d gases, wh ereby t h e fo rm in g wo rk is p er-
fo rm ed by a p ress u sin g a m et h o d sim ilar t o t h at em p lo yed wit h t h e rigid t o o ls. Th e great est field o f ap p licat io n o f t h is t ech n iq u e is hydro-
m echanical drawing, fo r exam p le fo r t h e m an u fact u re o f co m p o n en t s fro m st ain less st eel
Fig. 2.1.13 , cf.
Sect s. 4.2.4 an d
4.2.5 .
12
Basic principles of metal forming punch for 2 draw
nd
punch for 1 draw as blank holder
for redraw
st
initial hollow body
2 draw n part
nd
die
Fig. 2.1.11
M ultiple-draw deep draw ing w ith telescopic punch
die for 1 draw
st
blank holder for 1 draw
st
punch for1 draw as die for reverse draw
st
blank holder for reverse draw punch for reverse draw
Fig. 2.1.12
Reverse draw ing
Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998
Flanging is a m et h o d o f fo rm in g u n d er co m bin ed co m p ressive an d t en sile co n d it io n s u sin g a p u n ch an d d ie t o raise clo sed rim s flan ges o r
co llars o n p ierced h o les Fig. 2.1.14
. Th e h o les can be o n flat o r o n cu rved su rfaces. Flan ges are o ft en p ro vid ed wit h fem ale t h read s fo r t h e
p u rp o se o f assem bly. Spinning is a co m bin ed co m p ressive an d t en sile fo rm in g m et h o d u sed
t o t ran sfo rm a sh eet m et al blan k in t o a h o llo w bo d y o r t o ch an ge t h e p erip h ery o f a h o llo w bo d y. O n e t o o l co m p o n en t sp in n in g m an d rel,
sp in n in g bu sh co n t ain s t h e sh ap e o f t h e wo rkp iece an d t u rn s wit h t h e wo rkp iece, wh ile t h e m at in g t o o l ro ll h ead en gages o n ly lo cally
Fig. 2.1.15 . In co n t rast t o sh ear fo rm in g, t h e in t en t io n o f t h is p ro cess
is n o t t o alt er t h e sh eet m et al t h ickn ess. W rinkle bulging o r u p set bu lgin g is a m et h o d o f co m bin ed t en sile an d
co m p ressive fo rm in g fo r t h e lo cal exp an sio n o r red u ct io n o f a gen eral- ly t u bu lar sh ap ed p art . Th e p ressu re fo rces exert ed in t h e lo n git u d in al
d irect io n resu lt in bu lgin g o f t h e wo rkp iece t o ward s o u t sid e, in sid e o r in lat eral d irect io n
Fig. 2.1.16 .
13
M ethods of forming and cutting technology punch
blank holder seal
pressure medium container
pressure medium w orkpiece
Fig. 2.1.13
Hydromechanical deep draw ing
punch
blank holder
w orkpiece die
Fig. 2.1.14
Flanging w ith blank holder on a flat sheet
Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998
Form ing under tensile conditions Extending by stretching is a m et h o d o f t en sile fo rm in g by m ean s o f a t en -
sile fo rce ap p lied alo n g t h e lo n git u d in al axis o f t h e wo rkp iece. St ret ch fo rm in g is u sed t o in crease t h e wo rkp iece d im en sio n in t h e d irect io n o f
fo rce ap p licat io n , fo r exam p le t o ad ju st t o a p rescribed len gt h . Ten sile t est is also a p u re st ret ch in g p ro cess. St raigh t en in g by st ret ch in g is t h e
p ro cess o f ext en d in g fo r st raigh t en in g ro d s an d p ip es, as well as elim i- n at in g d en t s in sh eet m et al p art s.
14
Basic principles of metal forming spinning mandrel
spinning roller
circular blank w orkpiece
Fig. 2.1.15
Spinning a hollow body
pressure ring w orkpiece
punch container
ejector
Fig. 2.1.16
Wrinkle bulging to the outside
Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998
Exp an d in g is t en sile fo rm in g t o en large t h e p erip h ery o f a h o llo w bo d y. As in case o f d eep d rawin g, rigid
Fig. 2.1.17 as well as so ft t o o ls,
act ive m ed ia an d act ive en ergies are also u sed . Stretch form ing is a m et h o d o f t en sile fo rm in g u sed t o im p art im p res-
sio n s o r cavit ies in a flat o r co n vex sh eet m et al p art , wh ereby su rface en largem en t – in co n t rast t o d eep d rawin g – is ach ieved by red u cin g t h e
t h ickn ess o f t h e m et al. Th e m o st im p o rt an t ap p licat io n fo r st ret ch fo rm in g m akes u se o f a
rigid d ie. Th is t yp e o f p ro cess in clu d es also stretch drawing an d em boss- ing. St ret ch d rawin g is t h e creat io n o f an im p ressio n in a blan k u sin g
a rigid p u n ch wh ile t h e wo rkp iece is clam p ed firm ly aro u n d t h e rim Fig. 2.1.18
. Em bo ssin g is t h e p ro cess o f creat in g an im p ressio n u sin g a p u n ch in a m at in g t o o l, wh ereby t h e im p ressio n o r cavit y is sm all in
co m p ariso n t o t h e o verall d im en sio n o f t h e wo rkp iece Fig. 2.1.19
.
15
M ethods of forming and cutting technology
mandrel
w orkpiece
collet
punch w orkpiece
s s
1
1
s s
Fig. 2.1.18
Stretch forming
Fig. 2.1.17
Expanding by stretching
Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998
Form ing by bending In bending with a linear die m ovem ent t h e d ie co m p o n en t s m o ve in a
st raigh t lin e cf. Sect . 4.8.1. Th e m o st im p o rt an t p ro cess in t h is su b- cat ego ry is die bending, in wh ich t h e sh ap e o f t h e p art is im p act ed by t h e
d ie geo m et ry an d t h e elast ic reco very Fig. 2.1.20
. Die ben d in g can be co m bin ed wit h d ie co in in g in a sin gle st ro ke. Die co in in g is t h e rest rik-
in g o f ben t wo rkp ieces t o relieve st resses, fo r exam p le in o rd er t o red u ce t h e m agn it u d e o f sp rin gback.
Bending with rotary die m ovem ent in clu d es ro ll ben d in g, swivel ben d - in g an d circu lar ben d in g. Du rin g ro ll ben d in g, t h e ben d in g m o m en t is
ap p lied by m ean s o f ro llin g. Usin g t h e ro ll ben d in g p ro cess, it is p o ssi- ble t o m an u fact u re cylin d rical o r t ap ered wo rkp ieces
Fig. 2.1.21 . Th e
ro ll ben d in g p ro cess also in clu d es ro ll st raigh t en in g t o elim in at e u n d e- sirable d efo rm at io n s in sh eet m et al, wire, ro d s o r p ip es
Fig. 2.1.22 an d
cf. Sect . 4.8.3
as well as co rru gat in g an d ro ll fo rm in g Fig. 2.1.23
an d cf.
Sect . 4.8.2 .
16
Basic principles of metal forming
punch
die w orkpiece
Fig. 2.1.19
Embossing
punch w orkpiece
bending die
U die V die
Fig. 2.1.20
Die bending
Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998
Swivel bending is ben d in g u sin g a t o o l wh ich fo rm s t h e p art aro u n d t h e ben d in g ed ge
Fig. 2.1.24 . Circular bending is a co n t in u o u s p ro cess
o f ben d in g wh ich p ro gresses in t h e d irect io n o f t h e sh an k u sin g st rip , p ro file, ro d , wire o r t u bes
Fig. 2.1.25 . Circu lar ben d in g at an an gle
great er t h an 360°, fo r exam p le is u sed in t h e p ro d u ct io n o f sp rin gs an d is called co ilin g.
Form ing under shear conditions Displacem ent is a m et h o d o f fo rm in g wh ereby ad jacen t cro ss-sect io n s o f
t h e wo rkp iece are d isp laced p arallel t o each o t h er in t h e fo rm in g zo n e by a lin ear d ie m o vem en t
Fig. 2.1.26 . Disp lacem en t alo n g a clo sed d ie
ed ge can be u sed fo r exam p le fo r t h e m an u fact u re o f weld in g bo sses an d cen t erin g in d en t at io n s in sh eet m et al co m p o n en t s.
17
M ethods of forming and cutting technology
w orkpiece straightening rollers
Fig. 2.1.22
Roll straightening
w orkpiece rollers
Fig. 2.1.21
Roll bending
Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998
Twisting is a m et h o d o f fo rm in g u n d er sh earin g co n d it io n s in wh ich ad jacen t cro ss-sect io n al su rfaces o f t h e wo rkp ieces are d isp laced relat ive
t o each o t h er by a ro t ary m o vem en t Fig. 2.1.27
.
18
Basic principles of metal forming
Fig. 2.1.23
Roll forming
clamping jaw s w orkpiece
cheek
Fig. 2.1.24
Sw ivel bending
w orkpiece support w orkpiece
bending mandrel clamping fixture
Fig. 2.1.25
Circular bending
Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998
2.1.3 Dividing
