5.3.2 Feasibility studies
W h en d evelo p in g h yd ro fo rm ed co m p o n en t s, t h e p recise an alysis o f bo u n d ary co n d it io n s is essen t ial. O p t im u m d esign o f co m p o n en t s t ak-
in g in t o co n sid erat io n sp ecial p ro cess-sp ecific fact o rs en h an ces safet y an d also t h e co st -effect iven ess o f series p ro d u ct io n .
Th e feasibilit y st u d y, t h e co m p o n en t co n figu rat io n an d d efin it io n o f a p ro d u ct io n seq u en ce are clo sely in t erlin ked . O n ce t h ese p ro cesses
h ave p ro d u ced a p o sit ive resu lt , it is p o ssible t o st art wit h p ro t o t yp e d evelo p m en t o f t h e co m p o n en t s. W h en wo rkin g t h ro u gh t h e in d ivid -
u al st ep s, d ifferen t bo u n d ary co n d it io n s m u st be t aken in t o acco u n t . Th ese are briefly o u t lin ed belo w.
Review of feasibility W h en reviewin g feasibilit y, a d ifferen ce is d rawn bet ween t wo gro u p s o f
co m p o n en t s: n ew d evelo p m en t s wit h a geo m et ry t h at h as been co n fig- u red sp ecifically wit h h yd ro fo rm in g in m in d , an d t h e p ro d u ct io n o f
exist in g co m p o n en t s u sin g h yd ro fo rm t ech n o lo gy. Sign ifican t fact o rs h ere in clu d e t h e geo m et ry, wall t h ickn esses, m at e-
rials an d p ro cu rem en t o f t h e sem i-fin ish ed p art s o r p refo rm s. In it ially, t h e geo m et ry d at a is evalu at ed wit h t h e aid o f a CAD CAM syst em .
Circu m feren ces, rad ii, cro ss sect io n s an d t ran sit io n s are all d et erm in ed . A d ecisio n m u st also be t aken regard in g t h e ch aract erist ics o f t h e p re-
fo rm . In t h e case o f a t u be, fo r in st an ce, t h ese fact o rs wo u ld in clu d e t h e m at erial t o be u sed , t h e d iam et er, t h e wall t h ickn ess an d also an y p o s-
sible n eed fo r p re-fo rm in g. Th e exp ect ed circu m feren t ial exp an sio n is t h en d et erm in ed . Takin g
in t o acco u n t t h e m at erial d at a, t h e wall t h ickn ess, p re-fo rm in g o f t h e t u bu lar blan k an d o t h er bo u n d ary co n d it io n s, it is p o ssible t o assess t h e
m an u fact u rin g feasibilit y. Su bseq u en t ly, t h e in t ern al p ressu re, clo sin g fo rce, fo rces an d m o vem en t s o f t h e h o rizo n t al cylin d ers h ave t o be cal-
cu lat ed . Sin ce t h e co rrelat io n s bet ween all t h e d ifferen t in flu en cin g variables are h igh ly co m p lex, sp ecific exp ert ise is an essen t ial co m p o -
n en t o f su ccessfu l p art co n figu rat io n . Part configuration
If it is p o ssible t o m an u fact u re t h e p art , t h e n ext st age is t o d esign t h e d et ails, t h e p o sit io n in t h e d ie an d t h e slid e ch an n els. In t h e case, wh en
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a co m p o n en t d o es n o t ap p ear t o be p ro d u cible u sin g h yd ro fo rm in g t ech n o lo gy, an at t em p t is m ad e t o m o d ify t h e exist in g co n d it io n s in
su ch a way t h at t h e p art can be p ro d u ced wit h o u t m o d ifyin g it s fu n c- t io n al ch aract erist ics.
Th e p art geom etry m u st be op tim ized takin g in to accou n t th e p rocess lim its. W h ere assem blies are p rod u ced , it m ay u n d er certain circu m -
stan ces be p ossible to grou p several p arts in to a sin gle on e or to sp lit th e assem blies u p d ifferen tly. A d ifferen t m aterial can also be selected . W h en
m akin g th is typ e of m od ification , th e q u estion of reliability in series p ro- d u ction m u st n ot be n eglected , as th is is of d ecisive im p ortan ce con cern -
in g th e cost effectiven ess an d p rocess en gin eerin g related issu es. Configuration for series production
Th is st age in clu d es t h e d efin it io n o f a p ro d u ct io n seq u en ce an d co n fig- u rat io n o f t h e n ecessary p ro d u ct io n lin es. Co n sist en t im p lem en t at io n
o f t h e p ro t o t yp in g resu lt s is o f p art icu lar im p o rt an ce h ere. An o p t im u m p ro d u ct is o n ly ach ieved t h ro u gh effect ive in t eract io n o f t h eo ret ical
an alysis an d p ract ice-o rien t ed t est in g. An o t h er asp ect is t h e d efin it io n o f q u alit y-relevan t Q A d at a.
Form ing sim ulation Th e Fin it e Elem en t Met h o d FEM h as beco m e an est ablish ed feat u re o f
m et al fo rm in g t ech n o lo gy. Th e o bject ive o f FEM is t o rep lace co st ly an d elabo rat e exp erim en t al t est in g by fast , lo w-co st co m p u t er sim u lat io n .
An y p ract ical im p lem en t at io n o f p relim in ary co n sid erat io n s m u st t ake in t o acco u n t t h e sp ecial feat u res o f h yd ro fo rm in g:
– co n sid erat io n o f p art ial st rain h ard en in g o n p re-fo rm ed t u bes, – co rrelat io n bet ween p ro cess p aram et ers: m o t io n s an d fo rces o f t h e
h o rizo n t al cylin d ers, variat io n o f in t ern al p ressu re in t im e, m o t io n o f ad d it io n al d ie co m p o n en t s su ch as h o le p u n ch es an d co u n t erp res-
su re p u n ch es, clo sin g m o vem en t o f t h e d ie, – fu n ct io n al co o rd in at io n o f p ro cess p aram et ers: in t ern al p ressu re, d if-
feren t ad d it io n al d ie elem en t s su ch as h o le p u n ch es an d co u n t er- p ressu re p u n ch es an d axial cylin d ers,
– sp rin gback, – failu re crit eria: bu cklin g an d bu rst in g,
– m at erial beh avio r: an iso t ro p y an d flo w cu rve an d – d escrip t io n o f t h e co n t act frict io n co n d it io n s.
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Th e fo llo win g in fo rm at io n can be co m p u t ed u sin g a su it ably co n fig- u red FEM p ro gram :
– eq u ivalen t p last ic st rain , – effect ive st ress,
– t h ickn ess d ist ribu t io n , – d ist ribu t io n o f p last ic st rain rat e,
– p rin cip al st rain s an d – d ist an ce bet ween o u t er wall o f wo rkp iece an d t h e d ie wall.
5.3.3 Component design
Kategori