3
M E T A L F O R M I N G
H A N D B O O K
SCHULER GmbH
Bahnhofstr. 41
73033 Göppingen
Germany
Consulting editor: Professor Taylan Altan
Director, Engineering Research Center for Net Shape Manufacturing The Ohio State University, USA
Cataloging-in-Publication Data applied for Die Deutsche Bibliothek – CIP-Einheitsaufnahme
Metal forming handbook / Schuler. – Berlin ; Heidelberg ; New York ; Barcelona ; Budapest ; Hong Kong ; London ; Milan ; Paris ; Santa Clara ; Singapore ; Tokyo : Springer, 1998
Dt. Ausg. u. d. T.: Handbuch der Umformtechnik ISBN 3-540-61185-1
ISBN 3-540-61185-1 Springer-Verlag Berlin Heidelberg New York
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© Springer-Verlag Berlin Heidelberg 1998 Printed in Germany
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Preface
Fo llo win g t h e lo n g t rad it io n o f t h e Sch u ler Co m p an y, t h e Met al Fo r-m in g Han d bo o k p resen t s t h e scien t ific fu n d ar-m en t als o f r-m et al fo rr-m in g t ech n o lo gy in a way wh ich is bo t h co m p act an d easily u n d erst o o d . Th u s, t h is bo o k m akes t h e t h eo ry an d p ract ice o f t h is field accessible t o t each in g an d p ract ical im p lem en t at io n .
Th e first Sch u ler “Met al Fo rm in g Han d bo o k” was p u blish ed in 1930. Th e last ed it io n o f 1966, alread y revised fo u r t im es, was t ran slat ed in t o a n u m ber o f lan gu ages, an d m et wit h reso u n d in g ap p ro val aro u n d t h e glo be.
O ver t h e last 30 years, t h e field o f fo rm in g t ech n o lo gy h as been rad -ically ch an ged by a n u m ber o f in n o vat io n s. New fo rm in g t ech n iq u es an d ext en d ed p ro d u ct d esign p o ssibilit ies h ave been d evelo p ed an d in t ro d u ced . Th is Met al Fo rm in g Han d bo o k h as been fu n d am en t ally revised t o t ake acco u n t o f t h ese t ech n o lo gical ch an ges. It is bo t h a t ext bo o k an d a referen ce wo rk wh o se in it ial ch ap t ers are co n cern ed t o p ro -vid e a su rvey o f t h e fu n d am en t al p ro cesses o f fo rm in g t ech n o lo gy an d p ress d esign . Th e bo o k t h en go es o n t o p ro vid e an in -d ep t h st u d y o f t h e m ajo r field s o f sh eet m et al fo rm in g, cu t t in g, h yd ro fo rm in g an d so lid fo rm in g. A large n u m ber o f relevan t calcu lat io n s o ffers st at e o f t h e art so lu t io n s in t h e field o f m et al fo rm in g t ech n o lo gy. In p resen t in g t ech -n ical exp la-n at io -n s, p art icu lar em p h asis was p laced o -n easily u -n d er-st an d able grap h ic visu alizat io n . All illu er-st rat io n s an d d iagram s were co m p iled u sin g a st an d ard ized syst em o f fu n ct io n ally o rien t ed co lo r co d es wit h a view t o aid in g t h e read er’s u n d erst an d in g.
Th is Han d book is th e p rod u ct of d ed icated com m itm en t an d th e wid e ran ge of sp ecialized kn owled ge con tribu ted by m an y em p loyees of th e SCHULER Grou p in close coop eration with Prof. Dr.-In g. H. Hoffm an n an d Dip l.-In g. M. Kasp arbau er of th e utg, In stitu te for Metal Form in g an d Castin g at th e Tech n ical Un iversity of Mu n ich . In close coop eration with th e SCHULER team , th ey h ave created a solid fou n d ation for th e p ractical an d scien tific com p eten ce p resen ted in th is Han d book. We wish to offer ou r sin cere th an ks an d ap p reciation to all th ose in volved .
Go ep p in gen , March 1998
Sch u ler Gm bH
Bo ard o f Man agem en t
Contributors
ADAM, K., Dip l.-In g. (FH), SMG Sü d d eu tsch e Masch in en bau Gm bH & Co
BAREIS, A., Dip l.-In g. (FH), Sch u ler Pressen Gm bH & Co BIRZER, F., Prof. Dip l.-In g., Fein tool AG
BLASIG, N., Dip l.-In g. (FH), Sch leich er Au tom ation Gm bH & Co
BRANDSTETTER, R., Dip l.-In g. (FH), Sch u ler Pressen Gm bH & Co
BREUER, W., Dip l.-In g., Sch u ler Pressen Gm bH & Co
FRONTZEK, H., Dr.-In g., Sch u ler Gm bH
HOFFMANN, H., Prof. Dr.-In g., Leh rstu h l fü r Um form tech n ik u n d Gieß
e-reiwesen , Tech n isch e Un iversität Mü n ch en
JAROSCH, B., Dip l.-In g. (FH), Sch u ler Pressen Gm bH & Co
KÄSMACHER, H., SMG En gin eerin g fü r In d u striean lagen Gm bH
KASPARBAUER, M., Dip l.-In g., Leh rstu h l fü r Um form tech n ik u n d Gieß erei-wesen , Tech n isch e Un iversität Mü n ch en
KELLENBENZ, R., Dip l.-In g. (FH), Sch u ler Pressen Gm bH & Co
KIEFER, A., Dip l.-In g. (BA), GMG Au tom ation Gm bH & Co KLEIN, P., Gräben er Pressen system e Gm bH & Co. KG KLEMM, P., Dr.-In g., Sch u ler Pressen Gm bH & Co
KNAUß, V., Dip l.-In g. (FH), Sch u ler Werkzeu ge Gm bH & Co
KOHLER, H., Dip l.-In g., Sch u ler Gu ß Gm bH & Co
KÖRNER, E., Dr.-In g., Sch u ler Pressen Gm bH & Co
KUTSCHER, H.-W ., Dipl.-In g. (FH), Gräben er Pressen system e Gm bH & Co. KG LEITLOFF, F.-U., Dr.-In g., Sch äfer Hyd roform in g Gm bH & Co
MERKLE, D., Sch u ler Pressen Gm bH & Co
OSEN, W., Dr.- In g., SMG Sü d d eu tsch e Masch in en bau Gm bH & Co PFEIFLE, P., Dip l.-In g. (FH), Sch u ler Pressen Gm bH & Co
REITMEIER, C., Dip l.-In g., Sch äfer Hyd roform in g Gm bH & Co
REMPPIS, M., In g. grad ., Sch u ler Pressen Gm bH & Co
SCHÄFER, A.W., Sch äfer Hyd roform in g Gm bH & Co
SCHMID, W ., Dip l.-In g. (FH), Sch u ler Werkzeu ge Gm bH & Co
SCHMITT, K. P., Sch u ler Pressen Gm bH & Co
SCHNEIDER, F., Dip l.-In g. (FH), Sch u ler Pressen Gm bH & Co SIMON, H., Dr.-In g., Sch u ler Werkzeu ge Gm bH & Co
STEINMETZ, M., Dip l.-Wirt.-In g., SMG En gin eerin g fü r In d u striean lagen
Gm bH
STROMMER, K., Dip l.-In g. (FH), Sch u ler Pressen Gm bH & Co
VOGEL, N., Dip l.-In g., Sch leich er Au tom ation Gm bH & Co WEGENER, K., Dr.-In g., Sch u ler Pressen Gm bH & Co
Contents
In dex o f fo rm ula sy m bo ls . . . XV
1 In tro ductio n . . . . 1
2 Basic prin ciples o f m etal fo rm in g . . . . 5
2 .1 Meth o ds o f fo rm in g an d cuttin g tech n o lo gy . . . 5
2.1.1 Su m m ary . . . 5
2.1.2 Fo rm in g . . . 6
2.1.3 Divid in g . . . 19
2.1.4 Co m bin at io n s o f p ro cesses in m an u fact u rin g . . . 22
2 .2 Basic term s . . . 25
2.2.1 Flo w co n d it io n an d flo w cu rve . . . 25
2.2.2 Defo rm at io n an d m at erial flo w . . . 26
2.2.3 Fo rce an d wo rk . . . 28
2.2.4 Fo rm abilit y . . . 30
2.2.5 Un it s o f m easu rem en t . . . 31
Bibliography . . . 32
3 Fun dam en tals o f press design . . . 33
3 .1 Press ty pes an d press co n structio n . . . 33
3.1.1 Press fram e . . . 34
3.1.2 Slid e d rive . . . 37
3.1.3 Drive syst em s fo r d eep d rawin g p resses . . . 41
3 .2 Mech an ical presses . . . 49
3.2.1 Det erm in at io n o f ch aract erist ic d at a . . . 49
3.2.2 Typ es o f d rive syst em . . . 54
3.2.3 Drive m o t o r an d flywh eel . . . 60
3.2.4 Clu t ch an d brake . . . 61
3.2.5 Lo n git u d in al an d t ran sverse sh aft d rive . . . 63
3.2.6 Gear d rives . . . 65
3.2.7 Press cro wn assem bly . . . 66
3.2.8 Slid e an d blan k h o ld er . . . 66
3.2.9 Pn eu m at ic syst em . . . 70
3.2.10 Hyd rau lic syst em . . . 71
3.2.11 Lu bricat io n . . . 72
3 .3 Hy draulic presses . . . 73
3.3.1 Drive syst em . . . 73
3.3.2 Hyd rau lic o il . . . 77
3.3.3 Parallelism o f t h e slid e . . . 80
3.3.4 St ro ke lim it at io n an d d am p in g . . . 82
3.3.5 Slid e lo ckin g . . . 83
3 .4 Ch an gin g dies . . . 86
3.4.1 Die h an d lin g . . . 86
3.4.2 Die clam p in g d evices . . . 91
3 .5 Press co n tro l sy stem s . . . 94
3.5.1 Fu n ct io n s o f t h e co n t ro l syst em . . . 94
3.5.2 Elect rical co m p o n en t s o f p resses . . . 94
3.5.3 O p erat in g an d visu alizat io n syst em . . . 95
3.5.4 St ru ct u re o f elect rical co n t ro l syst em s . . . 97
3.5.5 Fu n ct io n al st ru ct u re o f t h e co n t ro l syst em . . . 99
3.5.6 Majo r elect ro n ic co n t ro l co m p o n en t s . . . 99
3.5.7 Arch it ect u re an d h ard ware co n figu rat io n . . . 101
3.5.8 Arch it ect u re o f t h e PLC so ft ware . . . 101
3.5.9 Fu t u re o u t lo o k . . . 102
3 .6 Press safety an d certificatio n . . . 106
3.6.1 Accid en t p reven t io n . . . 106
3.6.2 Legislat io n . . . 107
3.6.3 Eu ro p ean safet y req u irem en t s . . . 107
3.6.4 CE m arkin g . . . 111
3.6.5 Measu res t o be u n d ert aken by t h e u ser . . . 115
3.6.6 Safet y req u irem en t s in t h e USA . . . 117
3 .7 Castin g co m po n en ts fo r presses . . . 120
Bibliography . . . 122
4 Sh eet m etal fo rm in g an d blan kin g . . . 123
4 .1 Prin ciples o f die m an ufacture . . . 123
4.1.1 Classificat io n o f d ies . . . 123
4.1.2 Die d evelo p m en t . . . 128
4.1.3 Die m at erials . . . 142
4.1.4 Cast in g o f d ies . . . 142
4.1.5 Try-o u t eq u ip m en t . . . 148
4.1.6 Tran sfer sim u lat o rs . . . 154
4 .2 Deep draw in g an d stretch draw in g . . . 156
4.2.1 Fo rm in g p ro cess . . . 156
4.2.2 Mat erials fo r sh eet m et al fo rm in g . . . 174
4.2.3 Frict io n , wear an d lu bricat io n d u rin g sh eet m et al fo rm in g . . . 179
4.2.4 Hyd ro -m ech an ical d eep d rawin g . . . 185
4.2.5 Act ive h yd ro -m ech an ical d rawin g . . . 188
4 .3 Co il lin es . . . 194
4 .4 Sh eet m etal fo rm in g lin es . . . 198
4.4.1 Un iversal p resses . . . 198
4.4.2 Pro d u ct io n lin es fo r t h e m an u fact u re o f flat rad iat o r p lat es . . . 208
4.4.3 Lin es fo r sid e m em ber m an u fact u re . . . 210
4.4.4 Dest ackers an d blan k t u rn o ver st at io n s . . . 217
4.4.5 Press lin es . . . 222
4.4.6 Tran sfer p resses fo r sm all an d m ed iu m sized p art s . . . 229
4.4.7 Large-p an el t ri-axis t ran sfer p resses . . . 234
4.4.8 Cro ssbar t ran sfer p resses . . . 243
4.4.9 Presses fo r p last ics . . . 250
4.4.10 St ackin g u n it s fo r fin ish ed p art s . . . 252
4.4.11 Co n t ro l syst em s fo r large-p an el t ran sfer p resses . . 254
XI
4 .5 Blan kin g pro cesses . . . 268
4 .6 Sh earin g lin es . . . 284
4.6.1 Slit t in g lin es . . . 284
4.6.2 Blan kin g lin es . . . 286
4.6.3 High -sp eed blan kin g lin es . . . 291
4.6.4 Lin es fo r t h e p ro d u ct io n o f elect ric m o t o r lam in at io n s . . . 296
4.6.5 Pro d u ct io n an d p ro cessin g o f t ailo red blan ks . . . . 310
4.6.6 Perfo rat in g p resses . . . 314
4.6.7 Co n t ro l syst em s fo r blan kin g p resses . . . 320
4 .7 Fin e blan kin g . . . 330
4.7.1 Fin e blan kin g p ro cess . . . 330
4.7.2 Fin e blan kin g m at erials, fo rces, q u alit y ch aract erist ics an d p art variet y . . . 338
4.7.3 Fin e blan kin g t o o ls . . . 351
4.7.4 Fin e blan kin g p resses an d lin es . . . 359
4 .8 Ben din g . . . 366
4.8.1 Ben d in g p ro cess . . . 366
4.8.2 Ro ll fo rm in g an d variet y o f sect io n s . . . 373
4.8.3 Ro ller st raigh t en in g . . . 383
4 .9 Organ izatio n o f stam pin g plan ts . . . 389
4.9.1 Design . . . 389
4.9.2 Layo u t . . . 391
4.9.3 Q u alit y assu ran ce t h ro u gh q u alit y co n t ro l . . . 398
Bibliography . . . 403
5 Hy dro fo rm in g . . . 405
5 .1 Gen eral . . . 405
5 .2 Pro cess tech n o lo gy an d ex am ple applicatio n s . . . 405
5.2.1 Pro cess t ech n o lo gy . . . 405
5.2.2 Typ es o f h yd ro fo rm ed co m p o n en t s . . . 408
5.2.3 Field s o f ap p licat io n . . . 410
5 .3 Co m po n en t dev elo pm en t . . . 413
5.3.1 User-o rien t ed p ro ject m an agem en t . . . 413
5.3.2 Feasibilit y st u d ies . . . 414
5.3.3 Co m p o n en t d esign . . . 416
5 .4 Die en gin eerin g . . . 420
5.4.1 Die layo u t . . . 420
5.4.2 Lu brican t s . . . 422
5 .5 Materials an d prefo rm s fo r pro ducin g h y dro fo rm ed co m po n en ts . . . 423
5.5.1 Mat erials an d h eat t reat m en t . . . 423
5.5.2 Prefo rm s an d p rep arat io n . . . 424
5 .6 Presses fo r h y dro fo rm in g . . . 426
5 .7 Gen eral co n sideratio n s . . . 429
5.7.1 Pro d u ct io n t ech n o lo gy issu es . . . 429
5.7.2 Tech n ical an d eco n o m ic co n sid erat io n s . . . 431
Bibliography . . . 432
6 So lid fo rm in g (Fo rgin g) . . . 433
6 .1 Gen eral . . . 433
6 .2 Ben efits o f so lid fo rm in g . . . 441
6.2.1 Eco n o m ic asp ect s . . . 441
6.2.2 Wo rkp iece p ro p ert ies . . . 443
6 .3 Materials, billet pro ductio n an d surface treatm en t . . . 450
6.3.1 Mat erials. . . 450
6.3.2 Billet o r slu g p rep arat io n . . . 454
6.3.3 Su rface t reat m en t . . . 459
6 .4 Fo rm ed part an d pro cess plan . . . 464
6.4.1 Th e fo rm ed p art . . . 464
6.4.2 Pro cess p lan . . . 467
6 .5 Fo rce an d w o rk requirem en t . . . 469
6.5.1 Fo rward ro d ext ru sio n . . . 469
6.5.2 Fo rward t u be ext ru sio n . . . 474
XIII
6.5.3 Backward cu p ext ru sio n an d cen t erin g . . . 474
6.5.4 Red u cin g (o p en d ie fo rward ext ru sio n ) . . . 475
6.5.5 Iro n in g . . . 476
6.5.6 Up set t in g . . . 476
6.5.7 Lat eral ext ru sio n . . . 477
6 .6 Part tran sfer . . . 478
6.6.1 Lo ad in g st at io n . . . 479
6.6.2 Tran sfer st u d y . . . 481
6 .7 Die design . . . 485
6.7.1 Die h o ld ers . . . 488
6.7.2 Die an d p u n ch d esign . . . 491
6.7.3 Die an d p u n ch m at erials . . . 496
6.7.4 Die clo sin g syst em s (m u lt ip le-act io n d ies) . . . 502
6 .8 Presses used fo r so lid fo rm in g . . . 505
6.8.1 Ch o ice o f p ress . . . 505
6.8.2 Mech an ical p resses . . . 507
6.8.3 Hyd rau lic p resses . . . 514
6.8.4 Su p p lem en t ary eq u ip m en t . . . 517
6.8.5 Sp ecial feat u res o f h o t an d warm fo rm in g lin es . . 520
6.8.6 Sizin g an d co in in g p resses . . . 522
6.8.7 Min t in g an d co in blan kin g lin es . . . 526
Bibliography . . . 541
In d ex . . . 543
Index of formula symbols
a rib an gle, ben d in g an gle, °
clearan ce an gle, °
d ie o p en in g an gle, °
co rn er an gle fo r blan kin g °
a1 req u ired ben d in g an gle °
a2 d esired ben d in g an gle °
b d raw rat io ,
co rn er an gle wh en ben d in g °
bt o t t o t al d raw rat io bm ax m axim u m d raw rat io
« elo n gat io n , st art in g m easu rem en t
«A relat ive cro ss sect io n ch an ge %
h efficien cy
hA d egree of u tilization of th e sh eet m etal, u tilization force
hF fo rm in g efficien cy fact o r m co efficien t o f frict io n
V vo lu m et ric flo w 1/ s
s st ress N/ m m2
sm m ean st ress N/ m m2
sm ax largest st ress N/ m m2
sm d m ean co m p arat ive st ress N/ m m2
sm in sm allest st ress N/ m m2
sN n o rm al co n t act st ress N/ m m2
sr rad ial st ress N/ m m2
st t an gen t ial st ress N/ m m2
sv co m p arat ive st ress, effect ive st ress N/ m m2
sz crit ical bu cklin g st ress N/ m m2
s1 great est p rin cip le st ress N/ m m2
s2 m ean p rin cip le st ress N/ m m2
s3 sm allest p rin cip le st ress N/ m m2
tR frict io n al sh ear st ress N/ m m2
w d egree o f d efo rm at io n , st rain , lo garit h m ic/ t ru e st rain
w st rain rat e, d efo rm at io n rat e, d efo rm at io n sp eed
wB fract u re st rain
wg p rin cip le d efo rm at io n
w1,w2,w3 d efo rm at io n in m ain d irect io n s
A su rface m m2
a blan kin g p lat e m easu rem en t , rim wid t h , m m
leg len gt h d u rin g ben d in g, slo t wid t h m m
A0 in it ial su rface, su rface o f blan k cro ss sect io n m m2
a1 blan kin g p u n ch d im en sio n m m
A1 su rface o f blan k cro ss sect io n , en d su rface m m2
A5, A80 u lt im at e elo n gat io n %
AG eject o r su rface, su rface area u n d er p ressu re by
t h e eject o r m m2
aR sp ace bet ween t h e ro ws m m
AS sh eared su rface m m2
ASt cro ss sect io n o f t h e p u n ch , m m2
su rface area o f h o le p u n ch m m2
AZ blan k su rface, area o f t h e blan k m m2
b web wid t h , leg len gt h d u rin g ben d in g, m m
st rip wid t h , sect io n wid t h m m
B d eflect io n m m
bA sh ell-sh ap ed t ear wid t h m m
bE d ie ro ll wid t h m m
bS st rip wid t h m m
c m at erial co efficien t
D blan k d iam et er, p lat e d iam et er, m m
m an d rel d iam et er m m
XVI M etal Forming Handbook
d in n er d iam et er, h o le d iam et er, m m
(p erfo rat in g) p u n ch d iam et er m m
d ’ in sid e d iam et er o f bo t t o m d ie m m
d0 blan k d iam et er, in it ial billet d iam et er m m
d1 d iam et er o f t h e d raw p u n ch in t h e first d rawin g m m o p erat io n , p u n ch d iam et er, en d d iam et er m m
d2 u p p er cu p d iam et er, o u t sid e d iam et er m m
d3 o u t sid e flan ge d iam et er m m
e o ff-cen t er p o sit io n o f fo rce ap p licat io n m m
E elast icit y m o d u le N/ m m2
F fo rce kN
f1, f2, f3 o ffset fact o rs
FA eject io n fo rce kN
FB blan k h o ld er fo rce kN
Fb ben d in g fo rce kN
FG co u n t erfo rce kN
FGa eject io n fo rce kN
FGes t o t al m ach in e fo rce kN
FN n o rm al fo rce kN
FN0 rat ed p ress fo rce, n o m in al lo ad kN
FR rad ial t en sio n fo rce, frict io n fo rce, vee-rin g fo rce kN
FRa st rip p in g fo rce kN
FRe react io n fo rce kN
FS blan kin g fo rce fo r p u n ch wit h flat gro u n d kN
wo rk su rface, sh earin g fo rce kN
FST slid e fo rce kN
Ft t an gen t ial co m p ressio n fo rce kN
FU p ressin g fo rce, fo rm in g fo rce, kN
m axim u m d rawin g fo rce kN
g gravit at io n al accelerat io n m / s2
h fo rm in g p at h , d rawin g st ro ke, d ist an ce, h eigh t , m m
p u n ch d isp lacem en t ; m m
lu bricat io n gap mm
H p lat e t h ickn ess m m
h0 in it ial billet h eigh t , h eigh t o f blan k m m
XVII
h1 fin al h eigh t o f a bo d y aft er co m p ressio n m m h1’ in t erm ed iat e h eigh t , h eigh t o f t h e t ru n cat ed co n e m m
h2 cu p h eigh t m m
hE d ie ro ll h eigh t m m
hG flash h eigh t m m
hR, HR h eigh t o f vee-rin g m m
hS1 sm o o t h cu t sect io n in case o f fract u re %
hS2 m in im al sm o o t h cu t sect io n in case o f
sh ell-sh ap ed fract u re %
i sid e cu t t er scrap m m
k co rrect io n fact o r
k2a co rrect io n co efficien t (an gle)
kf flo w st ress N/ m m2
kf0 flo w st ress at t h e st art o f t h e fo rm in g p ro cess N/ m m2
kf1 flo w st ress t o ward s t h e en d o f t h e fo rm in g p ro cess N/ m m2
kfm m ean st abilit y fact o r N/ m m2
kh co rrect io n co efficien t (h eigh t )
kR sp rin gback fact o r
kS sh earin g resist an ce, sh earin g st ren gt h , N/ m m2
relat ive blan kin g fo rce N/ m m2
kw d efo rm at io n resist an ce N/ m m2
kwm m ean d efo rm at io n resist an ce N/ m m2
l rib len gt h m m
L st rip len gt h , m an d rel len gt h m m
la rim len gt h m m
le web len gt h , st rip len gt h m m
lR len gt h o f vee-rin g m m
lS len gt h o f sh eared co n t o u r cu t m m
m m ass, kg
m o d u le o f a gear
Mx eccen t ric m o m en t o f lo ad aro u n d t h e x axis kNm
My eccen t ric m o m en t o f lo ad aro u n d t h e y axis kNm
P p erfo rm an ce, d rive p o wer W, kW
p p ressu re N/ m m2
pB sp ecific blan k h o ld er p ressu re N/ m m2
pG average co m p ressive st ress o n t h e co u n t erp u n ch N/ m m2
pi in t ern al p ressu re N/ m m2
pj co m p ressive st ress at t h e wall o f t h e bo t t o m d ie N/ m m2
pm m ean (h yd rau st at ic) p ressu re N/ m m2
pSt average co m p ressive st ress o n t h e p u n ch , N/ m m2
average fo rm in g p ressu re N/ m m2
qG sp ecific co u n t erfo rce, co u n t erp ressu re N/ m m2
r rad iu s m m
R co rn er rad iu s m m
ra ext ern al rad iu s o f an in sid e co n t o u r m m
Ra ext ern al rad iu s o f an o u t sid e co n t o u r m m
ReL lo wer yield st ren gt h N/ m m2
Rp 0,2 co m p ressio n lim it N/ m m2
ri in sid e ben d in g rad iu s, m m
in t ern al rad iu s o f an in sid e co n t o u r m m
Ri in t ern al rad iu s o f an o u t sid e co n t o u r m m
ri1 in sid e rad iu s at t h e d ie m m
ri2 in sid e rad iu s at t h e wo rkp iece m m
Rm t en sile st ren gt h o f t h e m at erial N/ m m2
Rt su rface ro u gh n ess mm
Rw ro ller rad iu s m m
Rz su rface ro u gh n ess mm
s sh eet m et al t h ickn ess, wall t h ickn ess, m m
blan k t h ickn ess m m
sR p o sit io n o f t h e cen t er o f fo rce (xs- u n d ys:
co o rd in at es o f t h e fo rce), cen t er o f gravit y m m
t p it ch m m
tw ro ller p it ch m m
u blan kin g clearan ce m m
U sp eed / st ro kin g sp eed , 1/ m in
cu t co n t o u r circu m feren ces, p u n ch p erim et er m m
v co u n t erbalan ce valu e d u rin g ben d in g, m m
co m p en sat io n fact o r m m
V feed st ep , m m
vo lu m e m m3
XIX
V0 st art in g vo lu m e, o verall vo lu m e, p art vo lu m e m m3
V1 in t erm ed iat e vo lu m e, co m p en sat io n valu e m m3
V1’ in t erm ed iat e vo lu m e, co m p en sat io n valu e m m3
V2 in t erm ed iat e vo lu m e, co m p en sat io n valu e m m3
Vd vo lu m e d isp laced d u rin g d efo rm at io n m m3
W d efo rm at io n / fo rm in g wo rk Nm , kNm
J, kJ
w d ie wid t h m m
Wb ben d in g wo rk Nm
Wd d rawin g wo rk o n d o u ble-act io n p resses, Nm , kNm
d raw en ergy o f a d o u ble-act io n p ress Nm , kNm
We d rawin g wo rk o n sin gle-act io n p resses, Nm , kNm
d raw en ergy o f a sin gle-act io n p ress Nm , kNm
wid referen ced d eform ation work, sp ecific form in g work Nm m / m m3
WN n o m in al wo rk fo r co n t in u o u s st ro kin g Nm , kNm
WS blan kin g wo rk, blan kin g en ergy, sh earin g wo rk Nm , kNm
x co rrect io n fact o r
xs lo cat io n o f t h e resu lt in g blan kin g fo rce
in t h e x d irect io n m m
ys lo cat io n o f t h e resu lt in g blan kin g fo rce
in t h e y d irect io n m m
z n o. of teeth of a gear, n o. of workp ieces
zw ro ller feed valu e m m
1 Introduction
Tech n ology h as exerted a far greater in flu en ce on th e d evelop m en t of ou r p ast th an m ost h istory books give cred it for. As late as th e 19th cen -tu ry, craftm an sh ip an d tech n ology were p ractically syn on ym ou s. It is on ly with th e ad ven t of m ech an isation – th rou gh th e u se of m ach in es – th at th e term tech n ology took on a n ew m ean in g of its own .
To d ay, t ech n o lo gy is o n e o f t h e bast io n s o f o u r m o d ern lifest yle an d t h e basis fo r o u r p ro sp erit y, in wh ich m et al fo rm in g t ech n o lo gy p lays a cen t ral ro le. Alo n gsid e t h e m an u fact u re o f sem i-fin ish ed p ro d u ct s t h ro u gh ro llin g, wire d rawin g an d ext ru sio n , t h e p ro d u ct io n o f d iscret e co m p o n en t s u sin g sh eet m et al an d so lid fo rm in g t ech n iq u es is o f m ajo r sign ifican ce. It s field s o f ap p licat io n ran ge fro m au t o m o t ive en gin eerin g, p ro d u ct io n leerin e an d co n t aeerin er co n st ru ct io n t h ro u gh t o t h e bu ild -in g co n st ru ct io n , h o u seh o ld ap p lian ce an d p ackag-in g -in d u st ries.
Th e m ach in e t o o l, wit h it s cap acit y t o p recisely gu id e an d d rive o n e o r m o re t o o ls fo r t h e m ach in in g o f m et al, h as beco m e a sym bo l o f eco -n o m ic m et alwo rki-n g. I-n t h e p ast , t h e wo rk p ro cesses t yp ically see-n i-n m et al fo rm in g t ech n o lo gy u sed t o be execu t ed in a series o f in d ivid u al o p erat io n s o n m an u ally o p erat ed m ach in e t o o ls. To d ay, h o wever, au t o -m at ic p ro d u ct io n cells an d in t erlin ked in d ivid u al -m ach in es t h ro u gh t o t h e co m p act p ro d u ct io n lin e wit h in t egrat ed feed , t ran sp o rt , m o n it o rin g an d frin ish ed p art st ackrin g syst em s are t h e st at e o f t h e art . Develo p -m en t s in t h is field creat ed t h e t ech n o lo gical basis t o allo w t h e ben efit s o f fo rm ed wo rkp ieces, su ch as a m o re favo rable flo w lin e, o p t im u m st ren gt h ch aract erist ics an d lo w m at erial an d en ergy in p u t , t o be co m -bin ed wit h h igh er p ro d u ct io n o u t p u t , d im en sio n al co n t ro l an d su rface q u alit y.
As a rep u ted Germ an m an u factu rer of m ach in e tools, th e com p an y
o f m o re t h an 150 years: Fro m t h e m an u ally o p erat ed sh eet m et al sh ear t o t h e fu lly au t o m at ic t ran sfer p ress fo r co m p let e car bo d y sid e p an els.
O ver t h e m illen n iu m s, t h e h an d wo rkin g o f m et al by fo rm in g reach ed wh at m ay st ill t o d ay be co n sid ered a rem arkable d egree o f skill, resu lt -in g -in t h e creat io n o f m agn ificen t wo rks -in go ld , silver, bro n ze, co p p er an d brass. It was o n ly in aro u n d 1800 t h at iro n sh eet p ro d u ced in ro llin g p lan t s began t o fin d it s way in t o t h e craft sm en ’s wo rksh o p s, req u irin g co m p let ely n ew p ro cessin g t ech n iq u es: In co n t rast t o n o n -ferro u s m et als, t h e m u ch h ard er an d m o re brit t le n ew m at erial co u ld be m o re eco n o m ically wo rked wit h t h e aid o f m ach in es.
In 1839, m ast er lo cksm it h Louis Schuler fo u n d ed a m o d est wo rksh o p co m p risin g p rim arily a t in sm it h ’s sh o p , as well as a blacksm it h ’s fo rge an d a sm it h y. Driven by h is Swabian bu sin ess sen se, h e co n sid ered t h e p o ssibilit ies o p en ed u p by t h e n ewly available, ch eap er iro n sh eet . He was q u ick t o realize t h at t h e in creased in p u t req u ired in t erm s o f p h ys-ical st ren gt h an d wo rkin g t im e, an d t h u s t h e m an u fact u rin g co st s in vo lved in p ro d u cin g t h e fin ish ed art icle were far t o o h igh t o ben efit fro m t h e favo rable p rice o f t h e iro n sh eet it self. St ep by st ep , Louis
Schuler acco rd in gly began t o rep lace m an u al wo rk p ro cesses by m ech an
-ical fixt u res an d d evices. He began t o m ech an ise h is wo rksh o p wit h sh eet sh ears, ben d in g m ach in es an d p ress breaks, wh ich were co n sid er-able in n o vat io n s in t h o se d ays.
In sp ired by t h e Wo rld Exh ibit io n in Lo n d o n in 1851, Louis Schuler d ecid ed t o co n cen t rat e h is act ivit ies en t irely o n p ro d u cin g m ach in es fo r sh eet m et al wo rkin g. His p ro d u ct io n ran ge was co n t in u o u sly ext en d ed t o in clu d e sh eet m et al st raigh t en in g m ach in es, m et al sp in n in g an d levellin g ben ch es, eccen t ric p resses, sp in d le p resses, t u rret , cran k an d d rawin g p resses, bo t h m ech an ically an d h yd rau lically p o wered , n o t ch -in g p resses as well as cu t t -in g an d fo rm -in g t o o ls an d d ies. As early as 1859, h e exp o rt ed h is first sh eet m et al fo rm in g m ach in es.
At t h e en d o f t h e 1870s, Schuler regist ered h is first p at en t fo r “In n o -vat io n s in p u n ch in g d ies, sh ears an d sim ilar”. In 1895, h e p at en t ed “Hyd rau lic d rawin g p resses wit h t wo p ist o n s fit t ed in t o each o t h er”, an d in t h e sam e year was also award ed first p rize at t h e Sh eet Met al In d u st ry Trad e Exh ibit io n in Leip zig. Wit h exp an sio n o f t h e p ro d u ct io n p ro gram , t h e wo rkfo rce as well as t h e co m p an y p rem ises h ad u n d er-go n e co n t in u o u s gro wt h (Fig. 1.1). Th e Sch u ler m ach in e t o o l co m p an y
was o n e o f t h e fo resigh t ed en t erp rises o f t h e d ay t o p io n eer t h e p ro cess o f d ifferen t iat io n t akin g p lace in t h e field o f m ach in e t o o l en gin eerin g. As a su p p lier o f m ach in es an d p ro d u ct io n lin es fo r in d u st rial m an -u fact -u re – in p art ic-u lar series p ro d -u ct io n – t h e co m p an y’s rep -u t at io n in creased rap id ly.
Th e in creasin g exp o rt vo lu m e an d a co n sist en t p ro cess o f d iversifica-t io n in iversifica-t h e field o f fo rm in g iversifica-t ech n o lo gy led iversifica-t o an early p ro cess o f glo b-alisat io n an d t o t h e d evelo p m en t o f t h e in t ern at io n alSCHULERGro u p o f Co m p an ies.
Th e SCHULERGro u p ’s p ro cess o f glo balisat io n go t u n d er way at t h e begin n in g o f t h e sixt ies wit h t h e fo u n d in g o f fo reign su bsid iaries. To -d ay, SCHULERru n s n o t o n ly eigh t m an u fact u rin g p lan t s in Germ an y bu t also ad d it io n al five p ro d u ct io n facilit ies in Fran ce, t h e US, Brazil an d Ch in a. Alo n gsid e it s wo rld -wid e n et wo rk o f sales agen cies, SCHULERh as also set u p it s o wn sales an d service cen t ers in Sp ain , In d ia, Malaysia an d Th ailan d .
An in t ern at io n allybased n et wo rk o f p ro d u ct io n facilit ies co o rd in at -ed fro m t h e p aren t p lan t in Go ep p in gen p erm it s rap id resp o n se t o t h e ch an ges t akin g p lace in t h e t arget ed m arket s. Pro d u ct io n in o verseas lo cat io n s brin gs abo u t n o t o n ly a red u ct io n in co st s bu t also creat es
3
Introduction
m ajo r st rat egic ben efit s by in creasin g “lo cal co n t en t ” an d so en su rin g an im p ro ved m arket p o sit io n .
Th e No rt h an d So u t h Am erican m arket s are su p p lied lo cally. Th e NAFTA area is co o rd in at ed by Sch u ler In c. in O h io , wh ile So u t h Am eri-ca’s co m m o n m arket , t h e Merco su l, is su p ervised fro m Brazil. Th e h igh st an d ard o f q u alit y ach ieved by t h e SCHULERp lan t in Brazil h as o p en ed u p even t h e m o st d em an d in g m arket s.
In t h e gro win g m arket o f Ch in a, t h e SCHULERGro u p ru n s t wo jo in t ven t u re co rp o rat io n s in co o p erat io n wit h Ch in ese p art n ers fo r t h e m an -u fact -u re o f m ech an ical p resses an d h yd ra-u lic p resses.
To d ay, we st an d o n t h e t h resh o ld t o a n ew m illen n iu m m arked by in creasin g m arket glo balisat io n an d rap id ly ch an gin g o rgan izat io n al an d p ro d u cin g st ru ct u res. Un d er t h ese rap id ly ch an gin g co n d it io n s, it is SCHULER’swo rkfo rce wh ich rem ain s t h e sin gle m o st im p o rt an t d et er-m in in g fact o r bet ween su ccess an d failu re. Th e t ech n o lo gical o rien t a-t io n o f a-t h e sa-t aff p ro vid es a-t h e in n o vaa-t ive im p ea-t u s wh ich will secu re a-t h e co m p an y’s d evelo p m en t as it m o ves in t o t h e 21st cen t u ry.
Th is Met al Fo rm in g Han d bo o k reflect s t h e t ech n ical co m p et en ce, t h e rich so u rce o f id eas an d t h e creat ivit y o f t h e SCHULERGro u p ’s wo rkfo rce. Th e bo o k t akes an in -d ep t h lo o k at t h e p io n eerin g st age o f d evelo p m en t reach ed by t o d ay’s p resses an d fo rm in g lin es, an d at relat ed p ro d u ct io n p ro cesses, wit h p art icu lar em p h asis o n t h e d evelo p m en t o f co n t ro l en gin eerin g an d au t o m at io n . Develo p m en t s in t h e classical field s o f d esign , m ech an ical en gin eerin g, d yn am ics an d h yd rau lics are n o w bein g in flu en ced t o an ever great er d egree by m o re recen t ly d evelo p ed t ech n o lo gies su ch as CAD, CAM, CIM, m ech at ro n ics, p ro cess sim u la-t io n an d co m p u la-t er-aid ed m easu rem en la-t an d p ro cess co n la-t ro l la-t ech n o lo gy. In t o d ay’s en viro n m en t , t h e m ain o bject ive o f ach ievin g en h an ced p ro d u ct q u alit y an d p ro d u ct ivit y is co u p led wit h lo wer in vest m en t an d o p erat in g co st s. In ad d it io n , q u est io n s o f reliabilit y, u p t im e, accid en t p reven t io n , p ro cess acco u n t in g, eco n o m ical u se o f reso u rces an d en vi-ro n m en t al co n servat io n p lay also a cen t ral vi-ro le.
In view o f t h e fu n d am en t al im p o rt an ce o f m et al fo rm in g t ech n o lo gy t o d ay, t h is Han d bo o k o ffers t h e read er a referen ce wo rk wh o se u sefu l-n ess st ret ch es t o p ract ically every bral-n ch o f il-n d u st ry. Th e bo o k p ro vid es an in d ep t h an alysis o f m o st o f t h e im p o rt an t m an u fact u rin g t ech -n o lo gies as a syst em co m p risi-n g t h e t h ree elem e-n t s: p ro cess, p ro d u ct io -n lin e an d p ro d u ct .
2 Basic principles of metal forming
2.1 M ethods of forming and cutting technology
2.1.1 Summary
As d escribed in DIN 8580, m an u fact u rin g p ro cesses are classified in t o six m ain gro u p s: p rim ary sh ap in g, m at erial fo rm in g, d ivid in g, jo in in g, m o d ifyin g m at erial p ro p ert y an d co atin g (Fig. 2.1.1).
Prim ary shaping is th e creation of an in itial sh ap e from th e m olten ,
gaseou s or form less solid state. Divid in g is th e local sep aration of m ate-rial. Join in g is th e assem bly of in d ivid u al workp ieces to create su b-assem blies an d also th e fillin g an d satu ration of p orou s workp ieces. Coatin g m ean s th e ap p lication of th in layers on com p on en ts, for exam -p le by galvan ization , -p ain tin g an d foil wra-p -p in g. Th e -p u r-p ose of m od i-fyin g m aterial p rop erty is to alter m aterial ch aracteristics of a workp iece
coating dividing
joining
modifying material property
primary shaping
forming
Fig. 2.1.1
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 ree-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 ing (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
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 ifin 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 i-m , fo ri-m in g is p erfo ri-m ed in it ially at h o t fo ri-m in g t ei-m 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 iera-t io n era-t o ro llin g sem i-fin ish ed p ro d u cera-t 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
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
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 ifinished 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
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 ivi-d 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 re-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
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
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 exahydro-m p le fo r t h e hydro-m an u fact u re o f co hydro-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 drawnd punch for 1 draw as blank holder for redraw
st
initial hollow body
2 draw n partnd die
Fig. 2.1.11 M ultiple-draw deep draw ing w ith telescopic punch
die for 1 drawst
blank holder for 1 drawst
punch for1 draw as die for reverse draw
st
blank holder for reverse draw
punch for reverse draw
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
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 ii-n g d ei-n t s ii-n 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
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
s1
1 0
0 s < s
Fig. 2.1.18 Stretch forming
[image:35.439.54.220.74.171.2]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 rik-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 r-in 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. 2.1.22an 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
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
[image:37.439.52.218.73.187.2]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
[image:38.439.56.387.142.596.2]2.1.3 Dividing
Dividing is t h e first su bgro u p u n d er t h e h ead in g o f p art in g, bu t is gen
-erally cat ego rized as a “fo rm in g t ech n iq u e” sin ce it is o ft en u sed wit h o t h er co m p lem en t ary p ro d u ct io n p ro cesses (cf. Fig. 2.1.2). Acco rd in g
t o t h e d efin it io n o f t h e t erm , d ivid in g is t aken t o m ean t h e m ech an ical sep arat io n o f wo rkp ieces wit h o u t t h e creat io n o f ch ip s (n o n cu t -t in g). Acco rd in g -t o DIN 8588, -t h e d ivid in g ca-t ego ry in clu d es -t h e su b-cat ego ries sh ear cu t t in g, wed ge-act io n cu t t in g, t earin g an d breakin g
(Fig. 2.1.28). O f t h ese, t h e sh ear cu t t in g is t h e m o st im p o rt an t in in d u
s-t rial ap p licas-t io n .
19
M ethods of forming and cutting technology
punch
[image:39.439.50.213.73.367.2]w orkpiece blank holder
Fig. 2.1.26 Displacement
ϕ
w orkpiece
MT
Shear cutting – kn o wn in p ract ice as sh earin g fo r sh o rt – is t h e sep
ara-t io n o f wo rkp ieces beara-t ween ara-t wo cu ara-t ara-t in g ed ges m o vin g p asara-t each o ara-t h er (Fig. 2.1.29an d cf. Sect . 4.5).
Du rin g sin gle-stroke sh earin g, th e m aterial sep aration is p erform ed alon g th e sh earin g lin e in a sin gle stroke, in m u ch th e sam e way as u sin g a com p ou n d cu ttin g tool. Nibblin g, in con trast, is a p rogressive, m u lti-p le-stroke cu ttin g lti-p rocess u sin g a cu ttin g lti-p u n ch d u rin g wh ich sm all waste p ieces are sep arated from th e workp iece alon g th e cu ttin g lin e.
Fine blanking is a sin gle-st ro ke sh earin g m et h o d t h at u ses an an n u lar
serrat ed blan k h o ld er an d a co u n t erp ressu re p ad . Th u s t h e gen erat ed blan ked su rface is free o f an y in cip ien t bu rrs o r flaws, wh ich is fre-q u en t ly u sed as a fu n ct io n al su rface (Fig. 2.1.30 an d cf. Sect . 4.7).
20 Basic principles of metal forming
parting
dividing
breaking tearing
w edge-action cutting shear cutting
Fig. 2.1.28 Parting techniques classified under forming
open shearing blanking contour punch
die
W edge-action cutting o f wo rkp ieces is gen erally p erfo rm ed u sin g a
wed ge-sh ap ed cu t t in g ed ge. Th e wo rkp iece is d ivid ed bet ween t h e blad e an d a su p p o rt in g su rface. Bit e cu t t in g is a m et h o d u sed t o d ivid e a wo rkp iece u sin g t wo wed ge-sh ap ed blad es m o vin g t o ward s each o t h er. Th is cu t t in g m et h o d is em p lo yed by cu t t in g n ip p ers o r bo lt cu t t ers
(Fig. 2.1.31).
Th e p ro cesses tearing an d breaking su bject t h e wo rkp iece eit h er t o t en -sile st ress o r ben d in g o r ro t ary st ress beyo n d it s u lt im at e breakin g o r t en sile st ren gt h .
21
M ethods of forming and cutting technology
die counterpunch
punch
[image:41.439.54.181.442.590.2]serrated ring annular serrated blank holder
Fig. 2.1.30 Fine blanking
w orkpiece tool
2.1.4 Combinations of processes in manufacturing
Vario u s co m bin at io n s o f d ifferen t fo rm in g p ro cesses o r co m bin at io n s o f fo rm in g, cu t t in g an d jo in in g p ro cesses h ave been fo u n d t o be su c-cessfu l o ver m an y years.
Stretch drawing and deep drawing, fo r exam p le, assu m e an im p o rt an t
ro le in t h e sh eet m et al p ro cessin g in d u st ry (cf.Sect . 4.2.1). Du rin g st ret ch d rawin g, t h e blan k is p reven t ed fro m slid in g in t o t h e d ie u n d er t h e blan k h o ld er by m ean s o f a lo ckin g bead an d bead in g ro d s o r by ap p lyin g a su fficien t ly h igh blan k h o ld er fo rce (Fig. 2.1.32). As a resu lt ,
t h e blan k is su bject ed t o t en sile st ress d u rin g p en et rat io n o f t h e p u n ch . So t h e sh eet m et al t h ickn ess is red u ced .
Deep d rawin g, in co n t rast , is a p ro cess o f fo rm in g u n d er co m bin ed t en sile an d co m p ressio n co n d it io n s in wh ich t h e sh eet is fo rm ed u n d er t an gen t ial co m p ressive st ress an d rad ial t en sile st ress wit h o u t an y in t en t io n t o alt er t h e t h ickn ess o f t h e sh eet m et al (cf. Fig. 4.2.1).
Fo r exam p le wh en d rawin g co m p lex bo d y p an els fo r a p assen ger car, st ret ch d rawin g an d d eep d rawin g m ay be co n d u ct ed sim u lt an eo u sly. Th e t o o l co m p rises a p u n ch , d ie an d blan k h o ld er (Fig. 2.1.32). Th e
blan k h o ld er is u sed d u rin g st ret ch d rawin g t o act as a brake o n t h e m et -al, an d d u rin g d eep d rawin g t o p reven t t h e fo rm at io n o f wrin kles.
Mo d ern p ressin g t ech n iq u es t o d ay p erm it t h e d esired m o d ificat io n o f t h e blan k h o ld er fo rce d u rin g t h e d rawin g st ro ke. Th e blan k h o ld er fo rces can be ch an ged in d ep en d en t ly at vario u s lo cat io n s o f t h e blan k h o ld er d u rin g t h e d rawin g st ro ke. Th e blan k is in sert ed in t h e d ie an d clam p ed by t h e blan k h o ld er. Th e fo rm in g p ro cess begin s wit h p en et
ra-22 Basic principles of metal forming
draw ing w ith blank holder stretch forming deep draw ing
+ =
punch
blank holder
blank
die
FBl FBl FBl FBl
FSt FSt
s0 s0 s0
s0
s1
t io n o f t h e p u n ch t o p erfo rm a st ret ch d rawin g p ro cess in wh ich t h e wall t h ickn ess o f t h e st ret ch ed blan k is red u ced . Th e bo t t o m o f t h e d rawn p art is su bseq u en t ly fo rm ed .
Th e d eep d rawin g p ro cess begin s o n ce t h e req u ired blan k h o ld in g fo rce h as been red u ced t o t h e ext en t t h at t h e blan k m at erial is able t o flo w wit h o u t gen erat in g wrin kles o ver t h e ro u n d ed sect io n s o f t h e d ie. At t h e en d o f t h e d rawin g p ro cess, t h e blan k h o ld er fo rce is freq u en t ly in creased again in o rd er t o o bt ain a rep ro d u cible fin al geo m et ry by resp ect in g t h e st ret ch in g p o rt io n o f t h e d rawin g st ro ke.
In ad d it io n t o d eep d rawin g, bo d y p an els are ad d it io n ally p ro cessed in t h e st am p in g p lan t by fo rm in g u n d er ben d in g, co m p ressive an d sh earin g co n d it io n s. A ch aract erist ic o f t h e bending p ro cess is t h at a cam ber is fo rced o n t h e wo rkp iece in vo lvin g an gu lar ch an ges an d swiv-el m o t io n s bu t wit h o u t an y ch an ge in t h e sh eet t h ickn ess. Th e sp rin g-back o f t h e m at erial resu lt in g fro m it s elast ic p ro p ert ies is co m p en sat ed for by overben d in g (cf.Sect. 4.8.1). An oth er p ossibility for obtain in g d im en sion ally p recise workp ieces is to com bin e com p ressive stresses with in tegrated restrikin g of th e workp iece in th e area of th e bottom d ead cen ter of th e slid e m ovem en t.
Form ing is alm o st always co m bin ed wit h cutting. Th e blan k fo r a sh eet
m et al p art is cu t o u t o f co il st o ck p rio r t o fo rm in g. Th e fo rm in g p ro cess is fo llo wed by t rim m in g, p iercin g o r cu t -o u t o f p art s (cf.Sect . 4.1.1).
If n eit h er t h e cu t t in g n o r t h e fo rm in g p ro cess d o m in at es t h e p ro -cessin g o f a sh eet m et al p art , t h is co m bin at io n o f m et h o d s is kn o wn as
blanking. W h ere great er p iece n u m bers are p ro d u ced , fo r m o st sm all
an d m ed iu m -sized p u n ch ed p art s a p ro gressive t o o l is u sed , fo r exam p le in t h e case o f fin e-ed ge blan kin g (cf.Sect . 4.7.3). Ho wever, so lid fo rm -in g p ro cesses o ft en also co m b-in e a n u m ber o f d ifferen t t ech n iq u es -in a sin gle set o f d ies (cf.Sect . 6.1).
Th e call fo r great er co st red u ct io n s d u rin g p art m an u fact u re h as bro u gh t abo u t t h e in t egrat io n o f ad d it io n al p ro d u ct io n t ech n iq u es in t h e fo rm in g p ro cess. St ackin g an d assem bly o f p u n ch ed p art s, fo r exam -p le, co m bin es n o t o n ly t h e classical blan kin g an d fo rm in g -p ro cesses bu t also jo in in g fo r t h e m an u fact u re o f fin ish ed st at o r an d ro t o r assem -blies fo r t h e elect ric m o t o r in d u st ry (Fig. 2.1.33, cf. Fig. 4.6.22 an d 4.6.23). Sh eet m et al p art s can also be jo in ed by m ean s o f fo rm in g, by
t h e so -called h em m in g o r flan gin g (Fig. 2.1.34).
23
Dividing, coating and m odifying m aterial property technologies will su
bst an t ially exp an d t h e field o f ap p licat io n co vered by fo rm in g t ech n o lo gy in t h e fu t u re. Th is will allo w fin ish p ro cessin g in o n ly a sm all n u m -ber o f st at io n s, wh ere p o ssible in a sin gle lin e, an d will red u ce co st s fo r h an d lin g an d lo gist ics t h ro u gh o u t t h e p ro d u ct io n seq u en ce.
24 Basic principles of metal forming
Fig. 2.1.33 Joining by parting
Fig. 2.1.34
2 Basic principles of metal forming
2.2 Basic terms
2.2.1 Flow condition and flow curve
Met allic m at erials m ay be sh ap ed by ap p lyin g ext ern al fo rces t o t h em wit h o u t red u cin g t h eir st ru ct u ral co h esio n . Th is p ro p ert y is kn o wn as t h e fo rm abilit y o f m et al. Defo rm at io n o r flo w o ccu rs wh en t h e ro ws o f at o m s wit h in t h e in d ivid u al cryst allin e grain s are able, wh en st ressed beyo n d a cert ain lim it , t o slid e again st o n e an o t h er an d co h esio n bet ween t h e ro ws o f at o m s t akes p lace at t h e fo llo win g at o m ic lat t ice. Th is slid in g o ccu rs alo n g p lan es an d d irect io n s d et erm in ed by t h e crys-t allin e scrys-t ru ccrys-t u re an d is o n ly m ad e p o ssible by, fo r exam p le, d islo cacrys-t io n s (fau lt s in t h e arran gem en t o f t h e at o m ic lat t ice). O t h er flo w m ech n ism s su ch as t win cryst al fo rm at io n , in wh ich a p erm an en t d efo rm a-t io n is cau sed by a ro a-t aa-t io n o f a-t h e laa-t a-t ice fro m o n e p o sia-t io n a-t o an o a-t h er, p lay o n ly a m in o r ro le in m et al fo rm in g t ech n o lo gy.
Flo w co m m en ces at t h e m o m en t wh en t h e p rin cip le st ress d ifferen ce (
s
m ax–s
m in) reach es t h e valu e o f t h e flo w st ress kf, o r wh en t h e sh earst rain cau sed by a p u rely sh earin g st ress is eq u al t o h alf t h e flo w st ress, given by:
By n eglect in g t h e p rin cip le st ress
s
2, t h is m at h em at ical exp ressio n rep-resen t s an ap p ro xim at e so lu t io n o f t h e sh earin g st ress h yp o t h esis wit h t h e great est p rin cip le st ress
s
1an d t h e sm allest p rin cip le st resss
3:kf = σmax–σmin
Th e valu e o f t h e flo w st ress d ep en d s o n t h e m at erial, t h e t em p erat u re, t h e d efo rm at io n o r st rain ,
w
, an d t h e sp eed at wh ich d efo rm at io n o r st rain rat e is carried o u t ,w
. Belo w t h e recryst allisat io n t em p erat u re, t h e flo w st ress gen erally rises wit h in creasin g d efo rm at io n , wh ile t h e t em p erat u re an d d efo rm at io n rat e exert o n ly a m in im al in flu en ce. Excep -t io n s -t o -t h is ru le are fo rm in g -t ech n iq u es su ch as ro llin g an d fo rgin g, in wh ich ext rem ely h igh d efo rm at io n rat es are u sed . Abo ve t h e recryst allisarecryst io n recryst em p erarecryst u re, recryst h e flo w srecryst ress is gen erally su bjecrecryst recryst o recryst h e recryst em -p erat u re an d d efo rm at io n rat e, wh ile a -p revio u s d efo rm at io n h ist o ry h as o n ly m in im al in flu en ce. Th e flo w st ress gen erally d ro p s wit h in -creasin g t em p erat u re an d d e-creasin g d efo rm at io n rat e.Acco rd in gly, DIN 8582 d ifferen t iat es bet ween m et al fo rm in g p ro cess-es in vo lvin g a last in g ch an ge in st ren gt h p ro p ert icess-es an d t h o se in vo lvin g n o ap p reciable ch an ge in st ren gt h p ro p ert ies, p revio u sly d esign at ed as co ld an d h o t fo rm in g. In t h e t em p erat u re ran ge bet ween , d efo rm at io n in vo lves o n ly a t em p o rary ch an ge in t h e st ren gt h p ro p ert ies o f t h e m at erial. In t h is case, t h e d efo rm at io n sp eed is h igh er t h an t h e reco v-ery o r recryst allisat io n rat e. Recryst allisat io n st art s o n ly aft er co m p le-t io n o f le-t h e fo rm in g p ro cess. Th e ru les o f m ele-t al fo rm in g wile-t h lasle-t in g ch an ge in t h e st ren gt h p ro p ert ies ap p ly in t h is case.
Th e DIN 8582 st an d ard also breaks d o wn t h e p ro cess acco rd in g t o fo rm in g wit h o u t h eat in g (co ld fo rm in g) an d fo rm in g aft er t h e ap p lica-t io n o f h ealica-t (h o lica-t fo rm in g). Th ese lica-t erm s sim p ly sp ecify wh elica-t h er h ealica-t in g d evices are n ecessary. Un like t h eir fo rm er m ean in g, t h ese t erm s are n o t p h ysically relat ed t o t h e m at erial co n cern ed . Th e flo w st ress o f t h e in d i-vid u al m at erials is d et erm in ed by exp erim en t s in fu n ct io n o f d efo rm at io n (o r sat rain ) an d d efo rm aat io n raat e (o r sat rain raat e) aat at h e vario u s at em -p erat u re ran ges, an d d escribed in flo w cu rves. O n e o f t h e u ses o f flo w cu rves is t o aid t h e calcu lat io n o f p o ssible d efo rm at io n , fo rce, en ergy an d p erfo rm an ce.
2.2.2 Deformation and material flow
Act u al d efo rm at io n
w
, also called lo garit h m ic o r t ru e st rain , is given by:26 Basic principles of metal forming
.
ϕ1
1
0 0
1
=
∫
dh =h h h
h h
in wh ich
w
1is d efo rm at io n in
