Lines for side member manufacture

Th e slid e gib is m o u n t ed at six p o in t s in sp h erical ball jo in t s cf. Fig. 3.1.5 . Th e n eckin g act io n o f t h e p ress fram e wh ich o ccu rs u n d er lo ad is co m p en sat ed by a su p p lem en t ary in t ern al slid e gib in t h e bed . Pn eu m at ic slid e weigh t co m p en sat io n is p erfo rm ed by m ain t en an ce- free bello w cylin d ers cf. Fig. 3.2.11 . Th e d ie m o u n t in g area is d esign ed t o p erm it t h e u se o f all feasible d ie syst em s: – sin gle-act io n d ies fo r in d ivid u al rad iat o r p lat es, – d o u ble-act io n d ies wh ich can be u sed t o st am p t wo ad jacen t p lat es fro m wid e co il st o ck, – san d wich d ies in wh ich t wo blan ks are fed o n e abo ve t h e o t h er an d t wo p lat es, i. e. t o p an d bo t t o m p lat es are p ressed at t h e sam e t im e. Th e sh eet m at erial is fed by an elect rical ro ll feed syst em lo cat ed o n t h e back o f t h e p ress, abo ve t h e d rive syst em . Sp ecial fram e seals p reven t t h e d ie lu bricat in g em u lsio n fro m p en et rat in g in t o t h e d rivin g u n it . Su rp lu s em u lsio n is co llect ed in a p erip h eral gro o ve at t h e p ress bed o r p ress fram e an d ret u rn ed t o t h e syst em t o p erfo rm fu rt h er greasin g o r lu bricat io n wo rk. Th e lin e is co n t ro lled by a PLC co n t ro l syst em wit h o p erat o r gu id - an ce an d p ro gram p re-select io n fo r d ifferen t rad iat o r t yp es. Th e n u m - ber o f p art s n ecessary fo r co rresp o n d in g len gt h s can be p u t in t o t h e co n t ro ller by sp ecifyin g t h e ap p ro p riat e rad iat o r p lat e t yp e. Th e co m p let e lin e is su p p lem en t ed by a d eco iler an d a d ie ch an ge cart o r a d ie ch an ge syst em wit h q u ick-act io n d ie clam p in g o n t h e slid e o r bed p lat e cf. Sect . 3.4 . Scrap d isp o sal t akes p lace u n d er t h e d ie by m ean s o f a scrap ch u t e d irect ly in t o a scrap co n t ain er. All t h e d rive u n it s are accessible fro m t h e flo o r.

4.4.3 Lines for side member manufacture

Production m ethods Th e p ro d u ct io n o f ch assis sid e m em bers fo r t h e t ru ck in d u st ry is carried o u t in t wo st ep s: First , a blan k is cu t o u t an d p erfo rat ed . Next , t h e blan k is ben t t o a U-sh ap e t o fo rm a sid e m em ber, wh ile sim u lt an eo u sly web n ecks an d wh ere ap p licable also o ffset s are fo rm ed Fig. 4.4.12 . Left - an d righ t -h an d m em bers, fo r in st an ce, m u st be co n figu red in m irro r im age t o each o t h er an d h ave red u ced rib h eigh t s in t h e area o f t h e d ri- 210 Sheet metal forming and blanking Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998 ver’s cab. Bo t h o p erat io n s are gen erally execu t ed in a sin gle lin e u sin g t wo d ie set s. W h en m an u fact u rin g sid e m em bers, t wo d ifferen t m et h o d s are u sed in co n ju n ct io n wit h d ifferen t t yp es o f p ro d u ct io n lin es. Th ese are d is- t in gu ish ed fro m each o t h er alread y in t h e blan k feed st age. Sid e m em bers wit h a len gt h o f u p t o 7 m are gen erally m an u fact u red fro m plates, wh ich h ave a m axim u m t h ickn ess o f 4 m m . Th e p lat es are fed in t o t h e p ress o n an in t erm it t en t basis t ran sversely t o t h e lo n git u - d in al axis o f t h e p ress. Wit h each st ro ke t h e blan kin g d ie in t h e p ress p u n ch es a co n t o u red blan k fro m t h e p lat e. Th e blan k is t h en ben t in t h e n ext st at io n t o beco m e a sid e m em ber. To p ro d u ce sid e m em bers wit h a len gt h ran gin g fro m 4 t o 13 m , blanks wit h a t h ickn ess o f 5 t o 10 m m are available. Th e blan ks are gen erally cro ss-cu t d irect ly o ff t h e co il t o t h e co n t o u red blan k wid t h cf. Sect . 4.6.1 in o rd er t o en su re o p t im u m m at erial u t ilizat io n . Th e cam ber sh ap ed blan ks p ro d u ced u sin g t h is m et h o d h ave t o be co rrect - ed in a sep arat e u n it by st raigh t en in g. Th e st raigh t en ed blan ks are fed in d ivid u ally in t o t h e lo n git u d in al axis o f t h e p ress an d p ro cessed t o cre- 211 Sheet metal forming lines Fig. 4.4.12 Side members used in truck production Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998 at e a co n t o u red blan k. Th is is d o n e eit h er by an all ro u n d blan kin g st ro ke o r by lo cal ed ge blan kin g – gen erally at bo t h en d s o f t h e sid e m em ber. Th e ad van t age o f p ro cessin g sh eet p lat es is t h at t h e blan ks d o n o t assu m e a cam ber sh ap e d u e t o t h e all ro u n d blan kin g cu t u sed in t h eir m an u fact u re. Th u s, t h e st raigh t en in g p ro cess can be o m it t ed . Ho wever, in t h is case a lo wer d egree o f m at erial u t ilizat io n is ach ieved . In t h e case o f co m p lex sid e m em ber geo m et ries, in vo lvin g d ifferen t flan ge an d web h eigh t s, h o wever, it is p o ssible t o save o n m at erial in p u t by n est in g t h e co n t o u red blan ks cf. Fig. 4.5.2 to 4.5.5 . Th e blan kin g cu t leaves beh in d scrap webs wh ich are bro ken d o wn in t o scrap segm en t s. Production line concepts Th ere are t wo basic lin e t yp es u sed t o p ro d u ce sid e m em bers. Th ese d if- fer in p rin cip le, based o n t h e in feed an d o u t feed d irect io n o f t h e sh eet m et al: W h ereas sh eet p lat es belo w 7 m in len gt h can st ill be fed in t o t h e p ress t h ro u gh t h e p ress u p righ t s t ran sversely t o t h e lo n git u d in al p ress axis, lo n ger u n t reat ed blan ks h ave t o be fed p arallel t o t h e lo n git u d in al p ress axis. In lin es wh ere transport takes place parallel to the longitudinal press axis, t h e blan ks are fed by m ean s o f an in feed co n veyo r belt in sid e t h e p ress u p righ t s Fig. 4.4.13 . Cro ss-feed u n it s sim u lt an eo u sly feed t h e u n cu t blan k in t o t h e d ie an d t h e p revio u sly co n t o u red blan k o u t o f t h e d ie o n t o t h e reverse o u t feed co n veyo r. Tran sp o rt syst em s m akin g u se o f m agn et s are u sed t o st ack t h e co n t o u red blan ks em ergin g fro m t h e o u t - feed co n veyo r. In t egrat ed in t h e lin e is also a blan k t u rn in g st at io n . Th e lin es are d esign ed in su ch a way t h at bo t h , co n t o u red blan ks p u n ch ed fro m u n cu t blan ks an d sid e m em bers fo rm ed fro m co n t o u red blan ks, can be m an u fact u red . Im p o rt an t accesso ries fo r u se wit h fu lly au t o m at ic lin es in clu d e a blan k lu bricat in g o r sp rayin g d evice at t h e p ress in feed , a h o le p at t ern cam era t o d et ect p u n ch breakage an d a d evice fo r ed ge m illin g. Fu lly au t o m at ic lin es ach ieve cycle t im es o f 3 st ro kes p er m in u t e. Takin g in t o acco u n t t h e n eed fo r t wo p asses an d wit h o u t co n sid erin g t h e set -u p t im e o f aro u n d 15 m in req u ired fo r t h e ch an ge fro m blan kin g t o ben d - in g, t h is resu lt s in an average lin e o u t p u t o f so m e 1.5 sid e m em bers p er m in u t e. Die ch an geo ver also t akes p lace in t h e lo n git u d in al axis o f t h e p ress. 212 Sheet metal forming and blanking Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998 In t h e case o f p resses wit h m aterial transport transversely to the longitu- dinal press axis, t h e sh eet p lat es are gu id ed bet ween t h e p ress u p righ t s by m ean s o f a ch ain co n veyo r an d a grip p er feed d evice in syn ch ro - n izat io n wit h t h e p ress cycle. Aft er each st ro ke, t h e rem ain in g p lat e p u sh es t h e n ewly p u n ch ed co n t o u red blan k o n t o t h e reverse o u t feed co n veyo r belt . W h en an o p erat io n h as been co m p let ed , t h e wast e st rip o f t h e o ld p lat e m u st be d isp o sed o f t o get h er wit h t h e blan kin g wast e fro m t h e n ew p lat e. Th e eq u ip m en t u sed fo r d est ackin g t h e bales o f p lat es o r co n t o u red blan ks an d t h e o t h er elem en t s o f t h e lin e are t h e sam e as t h o se u sed in lin es t ran sp o rt in g t h e m at erial in t h e d irect io n o f t h e lo n git u d in al p ress axis. 213 Sheet metal forming lines Fig. 4.4.13 Layout of a line for the manufacture of truck side members F N = 50,000 kN, blanking shock damping and stroke limitation, 11 bed cushions, 25 slide ejectors, maximum off-center load: 25,000 kNm w ith electronic control of parallelity Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998 Die concept Th e blan kin g an d ben d in g d ie each co m p rise a basic d ie eq u ip p ed wit h t rim m in g an d p iercin g m o d u les in acco rd an ce wit h t h e vario u s sid e m em ber len gt h s. Sid e m em bers are st ru ct u red in su ch a way t h at cer- t ain gro u p s o f h o les, fo r exam p le t h o se u sed t o fast en t h e fro n t an d rear su sp en sio n m o u n t in g, are id en t ical an d o n ly ch an ge relat ive t o t h e wh eel base. In t h e area o f t h e d river’s cab at t h e fro n t en d o f t h e sid e m em ber, t h e co n t o u r an d h o le p at t ern s are id en t ical. Th e m o d u les are acco rd in gly ad ju st ed an d p o sit io n ed acco rd in g t o t h e req u irem en t s o f each in d ivid u al sid e m em ber t yp e: – fro n t m o d u le fo r t h e area o f t h e d river’s cab, – m ain m o d u le, fo r exam p le fo r t h e rear axle area, – in t erm ed iat e m o d u le t o brid ge d ifferen t sid e m em ber len gt h s an d – t h e en d m o d u le. If at all p ossible, righ t an d left-h an d sid e m em bers sh ou ld h ave th e sam e h ole p attern . On ly th en it is p ossible to m in im ize th e effort req u ired for d rawin g an d m ou n tin g p iercin g h ole p u n ch es wh en ch an gin g set-u p from righ t-h an d to left-h an d sid e m em bers. Th e sh earin g ed ges req u ired for blan kin g th e sid e m em ber con tou r d o n ot h ave to be reset, as for exam p le th e left-h an d con tou red blan k is p rod u ced from th e righ t-h an d con tou red blan k by sim p ly rotatin g it in th e tu rn in g station . However, for th e ben d in g p rocess, ben d in g d ies, form in g ed ges an d ejector beam s in th e asym m etrical areas m u st be ch an ged for a n ew set-u p . As t h e p o sit io n o f t h e fro n t m o d u le d o es n o t ch an ge, if t h e len gt h o f t h e sid e m em bers d ecreases, t h e p o sit io n o f t h e wo rkp ieces in t h e blan kin g an d ben d in g d ies beco m es in creasin gly o ff-cen t er. If a sin gle- sid ed co p in g cu t is t o be carried o u t at t h e sam e t im e, e. g. fo r exam p le wh en t rim m in g t h e fro n t , an ad d it io n al o ff-cen t er lo ad is ap p lied . Th e o ff-cen t er fo rces m u st be acco u n t ed fo r, eit h er by a balan cin g m o d u le o r by p ro vid in g a su it able p ress co n cep t . O t h erwise an u n accep t able am o u n t o f slid e t ilt in g act io n will o ccu r. To red u ce t h e blan kin g fo rce, t h e ed ges o f t h e blan kin g d ie an d p u n ch are co n figu red in a saw-t o o t h arran gem en t an d t h e p iercin g h o le p u n ch es are st aggered o n several blan kin g levels. Th e aim is t o ach ieve u n ifo rm lo ad in g o ver t h e en t ire len gt h o f t h e wo rkp iece at every blan k- in g p lan e. 214 Sheet metal forming and blanking Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998 Du rin g t h e ben d in g p ro cess, t h e web su rface o f t h e sid e m em ber is su p p o rt ed abo ve t h e bed cu sh io n by m ean s o f a su p p o rt beam . By vary- in g t h e bed cu sh io n p ressu re levels, it is p o ssible t o in flu en ce t h e flat - n ess o f t h e web su rface, an d in p art icu lar t h e rect an gu larit y o f t h e ribs. A st rip p in g d evice in t h e d ie en su res co n t ro lled st rip p in g o f t h e an gled sid e m em bers fro m t h e ben d in g p u n ch . Parallel eject io n is ach ieved u sin g t h e su p p o rt beam s. Segm ented bed cushion As a resu lt o f t h e variable sid e m em ber len gt h , t h e cu sh io n s at t h e en d zo n es o f t h e sid e m em bers are o n ly p art ially in u se. A t ilt in g m o m en t o ccu rs h ere wh ich m u st be balan ced by m ean s o f st able gibs. If all bed cu sh ion s are activated at th e sam e tim e d u rin g th e u p stroke of th e slid e for ejection , th e cu sh ion s wh ich h ave th e sm allest load reach th e top d ead cen ter first. However, th e sid e m em bers m u st be ejected in p arallel form ation in ord er to avoid d am age. Th ere are two altern atives h ere: to eject th e sid e m em ber wh ile m ain tain in g con tin u ou s con tact with th e top d ie d u rin g th e u p stroke of th e slid e, or to con trol th e syn - ch ron ou s ejection sp eed of all th e cu sh ion s. If sid e m em bers are form ed with righ t-an gled ben d s, d ifferen t cu sh ion strokes are req u ired . Control of parallelity and cylinder deactivation Th e p ist o n s o f t h e cylin d ers t h at co n t ro l p arallelit y are lo cat ed at t h e o u t sid e o f t h e slid e. Du rin g t h e wo rkin g st ro ke, t h ey o p erat e again st t h e m ean p ressu re o f t h e servo valves cf. Fig. 3.3.5 . Th e o ff-cen t er lo ad in g o f t h e d ies gen erat es a t ilt in g m o m en t o n t h e slid e. In t h e even t o f a d eviat io n fro m p arallelit y, t h e p ressu re is in creased in t h e co n t ro l cylin - d er t h at is o n t h e lo ad in g sid e wh ile p ressu re o n t h e o p p o sit e sid e is red u ced . A su p p o rt in g m o m en t o ccu rs wh ich act s o p p o sit e t o t h e t ilt - in g m o m en t . In t h e case o f sid e m em ber t o o ls, t h e o ff-cen t er lo ad in g o f t h e slid e can be large d u e t o t h e arran gem en t o f t h e in d ivid u al m o d - u les. In so m e cases, t ilt in g o f t h e slid e can n o lo n ger be p reven t ed by co n t ro l o f p arallelit y at a reaso n able co st . In su ch cases, t h e co n t ro l o f p arallelism is su p p o rt ed by t h e select ive d eact ivat io n o f in d ivid u al slid e cylin d ers Fig. 4.4.14 . As a resu lt , t h e cen t er o f ap p licat io n o f t h e p ress fo rce sh ift s in t h e d irect io n o f t h e fo rces gen erat ed in t h e d ies. Th e larg- er lever arm s o f t h e p arallelism co n t ro l fo rce h elp t o in crease t h e m o m en t act in g o p p o sit e t o t h e o ff-cen t er lo ad in g. Ho wever, d eact iva- t io n o f in d ivid u al cylin d ers red u ces t h e m axim u m available d ie fo rce. 215 Sheet metal forming lines Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998 216 Sheet metal forming and blanking Fig. 4.4.14 Tilt and parallelity control moments in a press for forming side members a F F F F F b b a slide cylinder parallelity control cylinder blanking shock damping center of loading center of loading controllable moment controllable moment F N = 5 x F – F PR1 – F PR2 F PR1 F PR2 long side members short side members deactivated cylinders F N F U F PR2 35 F N F U F PR2 Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998

4.4.4 Destackers and blank turnover stations