Slide drive Press types and press construction

in g th e correct d istribu tion of m aterial an d con figu ration of tran sition al rad ii between th e bed an d u p righ ts, as well as between th e u p righ ts an d p ress crown , it is p ossible to avoid exceed in g th e m axim u m p erm issible stress levels, also at rated force. An oth er ben efit of FEM-calcu lated com - p on en ts is th e ability to save on m aterial n ot n eed ed to en su re rigid ity. On top of th e press bed lies th e bed p late bolster p late u sed to cen ter an d h old d own th e lower h alf of th e d ie Fig. 3.1.1 an d cf. Sect. 3.4 . Th e bolster p lates on th e p ress bed an d th e slid e are screwed in to p lace to allow sim p le rem oval, for exam p le to alter th e T-n otch con figu ration , to retrofit h yd rau lic clam p in g d evices or to ad ap t th e op en in gs to n ew p ressin g req u irem en ts.

3.1.2 Slide drive

Th e p ress fram e abso rbs all t h e fo rces act in g o n t h e p ress, an d gu id es t h e slid e t o get h er wit h t h e u p p er d ie. Th e slid e, wh ich is m o ved in t h e vert ical d irect io n by a d rive syst em act in g in t h e press crown, t ran sfers t h e fo rm in g o r blan kin g fo rce t o t h e d ie. Alo n gsid e t h is t yp e o f top dri- ven press, t h ere are p resses wh o se d rive syst em is lo cat ed in t h e p ress bed . Th is t yp e o f bottom -driven press is u sed p rim arily fo r so lid fo rm in g, sp ecifically as co in in g p resses cf. Fig. 3.2.5 . A basic d ifferen ce exist s bet ween displacem ent-related, force-related and work-related presses. Th e 37 Press types and press construction one-point configuration two-point configuration four-point configuration Fig. 3.1.3 Connecting rod forces at the slide in one-, tw o- and four-point presses Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998 gro u p o f wo rk-relat ed p resses in clu d es screw p resses an d fo rgin g h am - m ers. Disp lacem en t an d wo rk-relat ed p resses are gen erally referred t o as m echanicalhydraulic p resses. In m ech an ical p resses, fo rce is t ran sm it t ed t o t h e slid e by m ean s o f co n n ect in g r o d s Fig. 3.1.9 , wh ile in h yd rau lic p resses t h is t ran sfer t akes p lace via t h e p ist o n ro d s o f t h e h yd rau lic cylin d er Fig. 3.1.10 . 38 Fundamentals of press design side w all cover plate gib prism eight-track slide gib support plate y base plate x front plate press frame front opening slide force FSt clamping grooves si de o pe ni ng Fig. 3.1.4 Design of the slide in a hydraulic press Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998 Dep en d in g o n t h e n u m ber o f fo rce t ran sm it t in g elem en t s, t h ere are one, two or four-point configurations in the slide Fig. 3.1.3 . W h en an o ff- cen t er lo ad is exert ed by t h e d ie o n t h e slid e, a m u lt ip le-p o in t p ress is bet t er able t o co u n t er t h e resu lt in g t ilt in g m o m en t . Th e slid e, wh ich gen erally h as a weld ed bo x sh ap e, is gu id ed in t h e p ress fram e Fig. 3.1.4 . In t h e case o f o ff-cen t er lo ad s, t h e slide gibs also p ro vid e p art o f t h e su p p o rt in g fo rces. Figure 3.1.5 illu st rat es so m e co m - m o n t yp es o f gibs. A m u lt ip le-p o in t p ress, u sed in co n ju n ct io n wit h a st able slid e gib syst em , o ffers t h e best co n d it io n s fo r ach ievin g go o d p art q u alit y an d a lo n g d ie life as a resu lt o f m in im al t ilt in g o f t h e slid e. Fo r large-scale p resses wit h t wo o r fo u r co n n ect in g ro d d rive syst em s, t h e gibs h ave lo n g gu id an ce len gt h s an d relat ively large vert ical elo n - gat io n o f t h e fram e. Th is calls fo r a read ju st m en t feat u re. Th e gib clear- an ce sh o u ld n o t exceed 0.1 m m . St an d ard d eep d rawin g p resses are eq u ip p ed wit h easily ad ju st able an d exch an geable 45° bro n ze gibs. In t h e case o f blan kin g an d t ran sfer 39 Press types and press construction Fig. 3.1.5 Different gib configurations column gib slide ball joint gib eight-track gib for w ide side uprights eight-track gib for narrow side uprights V-prism gib press w ith 2 side uprights press w ith 2 side uprights press w ith 4 side uprights press w ith 4 side uprights eight-track gib for high eccentric loads in the y direction eight-track block gib for high eccentric loads in the x and y direction x y z z Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998 p resses, eigh t -t rack gu id es an d exch an geable bro n ze gibs o n t h e slid e are t h e st at e o f t h e art . A reliable syst em o f cen t ral lu bricat io n is essen - t ial t o en su re o p t im u m gu id an ce. In st ead o f bro n ze slid e gibs, p last ic gibs are also u sed . Nowad ays, u n iversal p resses are freq u en tly con figu red with eigh tfold roller gibs Fig. 3.1.6 . Th is gu id an ce system is p reten sion ed free of gib clearan ce by in d ivid u al ap p lication of th e rollers, wh ich are each m ou n ted in roller bearin gs. Th e rollers are lu bricated an d sealed for life an d ru n on h ard en ed gu id e rails on th e p ress u p righ t free of oil or grease. Bo t t o m -d riven t o ggle p resses feat u re a lo n g p ress fram e wh ich calls fo r a sp ecial gu id an ce syst em t o co m p en sat e fo r n eckin g, t ilt an d p re- ven t h igh ed ge p ressu res cf. Fig. 3.2.5 . Card an u n iversal ball jo in t bear- in gs co m p en sat e fo r t ilt s an d en su re t h at t h e su p p o rt ive fu n ct io n is even ly sp read o ver t h e gibs Fig. 3.1.5 . Th ese gu id an ce co m p o n en t s can be u sed in an y p o sit io n : in sid e, o u t sid e, sixfo ld , eigh t fo ld o r in co m - bin at io n . 40 Fundamentals of press design Fig. 3.1.6 Roller gib Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998 Th e gu id an ce rat io , i. e. t h e rat io o f gu id e len gt h t o slid e len gt h , can be red u ced t o 1 : 3 in large-scale p resses wit h a h eigh t rest rict io n . Eccen - t ric p ress fo rces can o n ly be p art ially abso rbed by t h e gibs in t h is case. Fo r h o t fo rm in g ap p licat io n s, t h e exp an sio n o f t h e slid e d u e t o t em p er- at u re m u st be t aken in t o co n sid erat io n in t h e ch o ice o f slid e gibs. In t h is case, gu id an ce syst em s are u sed wh ich p erm it exp an sio n o f t h e slid e in o n e d irect io n wit h o u t gen erat in g ad d it io n al st resses Fig. 3.1.7 . Fo r eject io n o f p art s t h at m ay st ick t o t h e u p p er d ies, t h e slid e can be fit t ed wit h p n eu m at ic, h yd rau lic o r m ech an ical knock-out pins cf. Fig. 3.2.12 .

3.1.3 Drive systems for deep draw ing presses