In ad d ition , hole punching, notching, bending or threading p rocesses can be p erform ed on th e p art in cases wh ere th is h as n ot alread y been p erform ed
as p art of th e h yd roform in g seq u en ce itself Fig. 5.7.2
. By calibratin g th e p art, it is p ossible to p rod u ce sp ecial con tou rs at th e en d s of th e tu bes. A
sep arate p rocess is req u ired , gen erally by m ean s of weld in g, in ord er to assem ble add-on com ponents or to assem ble th e p art with oth er com p on en ts
p rod u ced u sin g d ifferen t p rod u ction p rocesses. In th e case of a production lot-related m ultiple pressing, com p on en ts th at are assem bled togeth er are
form ed in a sin gle p ressin g p rocess an d m u st be sep arated by cu ttin g.
5.7.2 Technical and economic considerations
Th e m o st im p o rt an t t ech n ical an d eco n o m ic asp ect s o f h yd ro fo rm in g are t h at :
– Co m p o n en t s wit h co m p lex geo m et ries can be m an u fact u red wh ich p revio u sly co u ld n o t be p ro d u ced in a sin gle p iece.
431
General considerations
Fig. 5.7.2
Hole punching, notching and bending during hydroforming
p
i
p
i
inw ard hole punching
notching and bending over
outw ard hole punching
Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998
– Th e sin gle-p art co n st ru ct io n elim in at es t h e n eed fo r weld in g seam s. – Th e calibrat io n p ro cess en su res a h igh d egree o f accu racy in t h e co n -
t o u rs an d d im en sio n s o f h yd ro fo rm ed co m p o n en t s. – St rain h ard en in g gen erally len d s h yd ro fo rm ed co m p o n en t s a h igh
d egree o f t o rsio n al rigid it y. Th eir elast ic reco very p ro p ert ies are less p ro n o u n ced t h an is t h e case wit h weld ed sh eet m et al sh ells. Fo r t h is
reaso n , it is o ft en p o ssible fo r t h e wall t h ickn ess o f h yd ro fo rm ed co m p o n en t s t o be relat ively lo w co m p ared t o cast p art s o r sh ell co n -
st ru ct io n s. Th is effect can be u sed eit h er t o red u ce weigh t o r t o en h an ce st ren gt h o r rigid it y.
– Usin g t h e sam e d ie, it is p o ssible t o u se an d t est t u bes wh ich , wit h in cert ain lim it s, h ave d ifferen t wall t h ickn esses an d st art in g d iam et ers
an d are m ad e o f d ifferen t m at erials p ro vid ed t h e u lt im at e d efo rm a- t io n is n o t exceed ed . Th is allo ws t h e weigh t an d st ren gt h p ro p ert ies
o f t h e p art t o be o p t im ized . – Exp erien ce h as sh o wn t h at lo wer flo w resist an ce an d larger fat igu e
st ren gt h are ach ieved in exh au st syst em s. By select ive co m p o n en t an d p ro cess co n figu rat io n , it is p o ssible t o save
bo t h en ergy an d m at erial an d t o red u ce d evelo p m en t an d p ro d u ct io n t im es. Th u s, gen erally it is p o ssible t o red u ce m an u fact u rin g co st s.
Bibliography
Leitloff, F.-U.: Innenhochdruckumformen mit dem Schäfer-ASE-Verfahren, Stahl 1995 5. M alle, K.: Aufw eiten - Stauchen - Expandieren, VDI Journal 137 1995 9.
N. N.: ASE-Verfahren bringt Hohlkörper in Form, Stahlmarkt 1993 4. N. N. : Hochdruckumformen - Fertigungsverfahren mit Zukunft, Stahl 1993 4.
N. N.: M it Wasser immer in Form, Automobil-Industrie 1993 4. N. N.: Schäfer bringt Hohlkörper in Form, Technische Informationsbroschüre zur Schäfer-ASE-
Technologie, Wilhelm Schäfer M aschinenbau GmbH Co. Schäfer, A. W., Fröb, K., Bieselt, R., Hassanzadah, G.: Kaltgeformte T-Stücke für den Anlagenbau –
Anforderungen und technische Realisierbarkeit, 3R International 29 1990 9.
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Hydroforming
Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998
6 Solid forming Forging
6.1 General
