Try-out equipment Principles of die manufacture .1 Classification of dies

– abilit y t o wo rk wit h co m p licat ed co m p o n en t s wit h sm all m an u fac- t u rin g t o leran ces, – bet t er d ist ribu t io n o f fo rces in t h e cast p iece via cu rvat u res an d sm o o t h blen d in g o f su rfaces, – better d am p in g ch aracteristics of cast iron com p ared to steel p late con - stru ction ; as a resu lt, q u iet an d low vibration p roven com p on en ts th at can be h igh ly stressed an d p rovid e low n oise level in p rod u ction , – less t en d en cy t o d ist o rt io n wit h cast iro n , wh ich en su res t h at a h igh level o f p recisio n is d elivered fro m t h e p ro d u ct io n syst em , – go o d wear an d slid in g ch aract erist ics, – d ie m at erials t h at can be h ard en ed ; t h u s, t h e cast co m p o n en t can fu llfill vario u s fu n ct io n al req u irem en t s wit h o u t an y ad d it io n al at - t ach m en t s, – o il-t igh t co n t ain ers, et c., – n o co rn ers an d cracks in t h e seam s, wh ich can lead t o abso rp t io n o f m o ist u re an d co rro sio n , – go o d m ach in abilit y, t h ro u gh wh ich savin gs in t h e o rd er o f 20 t o 50 o n m ach in in g co st s can be ach ieved , – as a ru le, n o st ress-relievin g p ro cess is n ecessary.

4.1.5 Try-out equipment

Try-out presses Eq u ip m en t fo r d ie t ry-o u t p lays an im p o rt an t ro le in m o d ern p resswo rk o p erat io n s. Dies are t est ed o n a t ry-o u t p ress befo re st art in g p ro d u ct io n . In t h is way, t h e d ie set -u p t im e o n a p ro d u ct io n lin e p ress is red u ced t o a m in im u m . Press ru n n in g t im es fo r all p art s are co n seq u en t ly lim it ed t o set -u p an d p ro d u ct io n t im e o n ly an d t h is in creases t h e p ro fit abilit y o f t h e p ro d u ct io n lin e. In m akin g d ies fo r sh eet m et al fo rm in g, t h e scu lp t u red su rface o f t h e d ie cavit y will be m ach in ed t o fo rm t h e m ale an d fem ale d ies u sin g t h e CAD-gen erat ed d at a fo r t h e fin ish ed p art . As a gen eral p ract ice, bo t h p arts of th e d ie are n orm ally p rod u ced from cast p attern s cf. Sect. 4.1.4 . Du rin g d ie d evelo p m en t o n a t ry-o u t p ress, it is p o ssible t o ascert ain fo r t h e first t im e, wh ere an y rewo rkin g n eed s t o be carried o u t o n t h e geo m et ry. Th e o p erat io n al ch aract erist ics o f t h e d ies an d t h e co n t act p at t ern are ch ecked o u t . Th e flo w o f t h e m at erial is evalu at ed t o see 148 Sheet metal forming and blanking Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998 h o w it co m p ares wit h t h e t h eo ret ical calcu lat io n s. Th e fo rm ed p art s are in sp ect ed fo r p resen ce o f an y wrin klin g, t ears o r bu lges. In p art icu lar, h igh m at erial t h ickn esses d o o ccu r in t h e co rn er areas o f t h e blan k h o ld er su rface becau se o f t an gen t ial co m p ressive st resses, wh ich lead t o u n d esirable h igh er su rface p ressu res an d can ad versely affect resu lt s o f t h e d eep d rawin g p ro cess. To rect ify t h is, it is n ecessary t o rem o ve m at e- rial an d rewo rk sp ecific areas o f t h e blan k h o ld er. In a t ry-o u t p ress, t h e d ie geo m et ry is m o d ified by first fo rm in g a p art an d t h en grin d in g t h e p u n ch , t h e d ie an d t h e blan k h o ld er at t h e m o st crit ical p o in t s in o rd er t o o bt ain t h e req u ired p art q u alit y. Th is p ro ce- d u re, e. g. fo rm in g an d regrin d in g, is rep eat ed u n t il go o d q u alit y p art s are fo rm ed . Th e aim is t o p erfect t h e d ie o n t h e t ry-o u t p ress, so t h at co st ly m o d ificat io n s fo r a series ru n o n a p ro d u ct io n p ress are m in i- m ized . Try-o u t o p erat io n s can o n ly be co n sid ered co m p let e wh en t h e req u ired p art q u alit y is ach ieved , i. e. wh en t h e first go o d p art is p ro - d u ced , an d p ro d u ct io n o n t h e p ro d u ct io n p resses can t h en st art . If t h e d raw cu sh io n o f a sin gle-act io n p ress o r fo r t h at m at t er, t h e blan k h o ld er o f a d o u ble-act io n p ress, is eq u ip p ed wit h a m u lt i p o in t co n t ro ller, t h e t ry-o u t co st s can be great ly red u ced cf. Sect . 3.1.4 an d 3.2.8 – t h e p ro d u ct io n p ress o n t o wh ich t h e d ie will lat er be in st alled an d t h e t ry-o u t p ress sh o u ld cert ain ly be eq u ip p ed , as far as p o ssible, wit h a sim ilar t yp e o f co n t ro l syst em . In st ead o f wo rkin g o n t h e sp e- cific d ie area, o r u sin g d raw bead s cf. Fig. 4.2.6 an d 4.2.7 , t h e req u ired d eep d rawin g resu lt can be ach ieved sim p ly by m akin g ad ju st m en t s o f in d ivid u al co n t ro l cylin d ers. An ad d it io n al d evice, wh ich co n t ro ls t h e p ressu re d u rin g t h e d raw st ro ke cf. Fig. 3.1.12 co n t ribu t es sign ifican t - ly t o red u cin g t ry-o u t co st s an d ach ievin g t h e h igh est p art q u alit y o n t h e p ro d u ct io n p ress. Du rin g t h e t ry-o u t p ro cess, t h e p aram et ers o f t h e fo rm in g o p erat io n , esp ecially t h o se wh ich can be ad ju st ed o n t h e act u al p ress bein g u sed , p lay a d ecisive ro le. Hyd rau lic an d m ech an ical t ry-o u t p resses t est t h e d ies u n d er co n d it io n s wh ich are as clo se as p o ssible t o t h o se fo u n d in n o rm al p ro d u ct io n ru n s. In o rd er t o ach ieve a fast er an d m o re reliable p ro d u ct io n st art -u p , a h igh d egree o f co m p at ibilit y o f t h e m ain p ress ch aract erist ics – su ch as t h e rigid it y an d t ran sverse ben d in g o f t h e bed an d slid e, et c. – bet ween t h e t ry-o u t p ress an d t h e st at io n s o f t h e p ro - d u ct io n p ress is an ad van t age. Th e clo ser t h e ch aract erist ics o f t h e t ry- o u t p ress are t o t h o se o f t h e p ro d u ct io n lin e p ress, t h e sh o rt er will be 149 Principles of die manufacture Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998 t h e t im e req u ired t o be sp en t d u rin g p ro d u ct io n st art -u p an d t h e so o n - er t h e p ro d u ct io n o f go o d p art s can be ach ieved . Fo r exam p le, t h e m o st su ccessfu l way o f d evelo p in g d ies fo r m ech an ical large-p an el t ran sfer p resses is t o u se m ech an ical t ry-o u t p resses, wh ich h ave n early id en t ical ch aract erist ics. In p art icu lar, t h is m ean s t h at fo r t h e first d rawin g st age, t h e t ry-o u t p ress, ap art fro m h avin g t h e sam e co n st ru ct io n , also h as a sim ilar d raw cu sh io n t o t h at o f t h e sin gle-act io n p ress Fig. 4.1.19 , left. O n e o r m o re sin gle-act io n m ech an ical p resses wit h o u t a d raw cu sh io n , h o wever, are u sed t o d evelo p t h e d ies fo r t h e su bseq u en t st at io n s o f a t ran sfer p ress Fig. 4.1.19 , right. A m u ch less exp en sive so lu t io n is p ro vid ed by h yd rau lic p resses Fig. 4.1.20 . Ad m it t ed ly, t h eir kin em at ic ch aract erist ics an d , in p art icu - lar, t h e fo rm in g sp eed can o n ly m at ch t h o se o f a m ech an ical p ress t o a lim it ed d egree cf. Fig. 3.2.3 to Fig. 3.3.1 ; bu t t h eir en ergy cap acit y d o es n o t d ep en d u p o n t h e st ro kin g rat e. Th eir flexibilit y m akes an y d esired slid e m o vem en t p o ssible irresp ect ive o f wh et h er t h e d o wl ed ges sh o u ld be carefu lly t est ed o r an y p re-p ro d u ct io n series o f st am p in gs are p ro - 150 Sheet metal forming and blanking Fig. 4.1.19 M echanical try-out presses for die try-out: w ith draw cushion for the first forming process left and w ithout draw cushion for the subsequent processes right Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998 d u ced . In ad d it io n , a sp o t t in g fixt u re fo r t h e slid e an d blan k h o ld er can be ap p lied t o t h e co n t o u rs o f t h e d ie wit h a p recisely co n t ro lled sp eed . Th e d ie m o u n t in g area, t h e st ro ke an d t h e fo rce o n all t ry-o u t p resses are so d esign ed t h at t h e p ress can acco m o d at e t h e t o t al ran ge o f large size t o o ls. Fo rce an d sp eed can be select ed in t h e rat io o f at least 1 : 10, so t h at t h e d ies can be t ried o u t by st art in g wit h a very lo w ram sp eed . As a ru le, bo t h t h e p u n ch an d t h e d ie m u st be rewo rked at t h e sam e t im e d u rin g d ie t ry-o u t . In o rd er t o facilit at e t h e rewo rk an d save t im e, h yd rau lic t ry-o u t p resses can be eq u ip p ed wit h a p ivo t in g slid e p lat e Fig. 4.1.21 . At first , t h e m o vin g bo lst er carryin g t h e lo wer d ie m o ves o u t o f t h e p ress. W h en p ivo t ed , t h e t o p d ie is ro t at ed t h ro u gh 180° an d lo wered an d cen t ered o n t o a m o vable p allet t ru ck. Aft er t h is, t h e slid e, t h e clam p in g p lat e an d t o p d ie are lo wered t o a p re-d efin ed h eigh t an d lo cked in t o t h e ro ll-o ver d evice. Th e q u ick-act io n clam p s release t h e slid e p lat e fro m t h e slid e, an d t h e slid e m o ves t o t h e t o p d ead cen t er p o sit io n . Aft er t h e slid e p lat e an d t o p d ie h ave been t u rn ed o ver, t h e slid e p laces t h e slid e p lat e wit h t h e t o p d ie in t h e cen t erin g o f t h e p allet t ru ck an d m o ves again t o t h e 151 Principles of die manufacture Fig. 4.1.20 Design of a hydraulic try-out press hydraulic draw cushion deep drawing ad ustment stepless slide locking blank holder cylinder slide cylinder marking stop slide cushion with adapter position sensor for the draw cushion spotting cylinder slide Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998 u p p er st o p p o sit io n . Aft er bein g t aken o u t o f t h e back o f t h e p ress o n t h e p allet t ru ck, t h e t o p d ie is accessible fro m all sid es. Th is allo ws co n - ven ien t an d t im e-savin g rewo rkin g t o be carried o u t . Aft er reverse ro t a- t io n , t h e d ie d o es n o t n eed t o be rep o sit io n ed as it is alread y p o sit io n ed by t h e clam p in g p lat e o n t h e p allet t ru ck. Th e elect rical syst em o f a t ry-o u t p ress in clu d es a sen so r syst em fo r m easu rin g t h e set t in g p aram et ers fo r each d ie. Sen so rs fo r m easu rin g vario u s p ro cess p aram et ers an d a d at a acq u isit io n syst em allo w t o p er- fo rm st at ist ical evalu at io n . Th e o p t im al set t in g p aram et ers are saved an d m ad e available as in p u t in t o t h e co n t ro l syst em o f t h e p ro d u ct io n p ress. In o rd er t o ach ieve p ro d u ct io n -like co n d it io n s in h yd rau lic t ry- o u t p resses, an y elast ic d efo rm at io n s o r o ff-cen t er m o vem en t s o f t h e slid e, wh ich are d et ect ed at t h e d ie an d t h e p ro d u ct io n lin e m u st be co n sid ered by t h e co n t ro l syst em . Du rin g ru n -in , t h e d ies n eed t o be freq u en t ly m o ved in an d o u t o f t h e p ress. A m o vin g bo lst er allo ws t h is wo rk t o be carried o u t fast er an d m o re safely cf. Fig. 3.4.3 . In a t ry-o u t cen t er fo r exam p le, several t ry- 152 Sheet metal forming and blanking Fig. 4.1.21 Rotating the slide of a hydraulic try-out press Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998 o u t p resses m ay be lin ked t o get h er wit h T-t racks Fig. 4.1.22 an d cf. Fig. 3.4.4 . Th is arran gem en t allo ws co m p reh en sive t est in g o f t h e p ro - gressive fo rm in g o p erat io n s so t h at d ie set s are m o re q u ickly an d effi- cien t ly ru n -in . Try-o u t p resses an d abo ve all t ry-o u t cen t ers are also su it able fo r p ro - d u cin g sh o rt ru n p art s o r carryin g o n p ro d u ct io n o n a sm aller scale in t h e even t o f t h e breakd o wn o f a large p ro d u ct io n p ress. Dep en d in g o n t h e t ask t h ey h ave t o p erfo rm , su ch u n iversal p resses m ay be u sed , fo r exam p le, fo r p ro d u ct io n as well as fo r t ry-o u t p u rp o ses. Parallel lift m echanism s Fo r an y rep airs an d rewo rkin g o p erat io n s, t h e t o p d ie h as t o be lift ed o ff t h e bo t t o m d ie. Fo r ergo n o m ic o verh ead wo rkin g an d sch ed u lin g rea- so n s wo rkin g at t h e sam e t im e o n t h e t o p an d bo t t o m d ies bo t h d ies are laid d o wn sep arat ely. Dies wh ich can n o t be h an d led m an u ally can be m o ved wit h t h e h elp o f a h yd rau lic p arallel lift m ech an ism . Th is ap p arat u s en su res q u ick clam p in g fo r rep airs an d m ain t en an ce o f d ies. 153 Principles of die manufacture Fig. 4.1.22 Try-out center: try-out presses linked by T-tracks Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998 Th e m ech an ism , seen in Fig. 4.1.23 , lift s t h e t o p d ie p arallel t o t h e lo w- er d ie, an d aft er a 180° t u rn p laces it n ext t o t h e lo wer d ie. Th e m ech a- n ism en su res t h at bo t h p art s o f t h e d ie are lift ed safely an d wit h co n - sist en t accu racy wit h o u t an y t ilt in g.

4.1.6 Transfer simulators