Types of hydroformed components

sio n al st at e o f st ress – wit h a relat ively h igh h yd ro st at ic st ress co m p o - n en t co m p ared t o d eep -d rawin g an d st ret ch d rawin g p ro cesses – rela- t ively h igh d egrees o f d efo rm at io n can be ach ieved cf. Sect s. 4.2.1 , 4.2.4 an d 4.2.5 .

5.2.2 Types of hydroformed components

A basic d ifferen ce is d rawn bet ween h yd ro fo rm ed co m p o n en t s wh ich p erm it t h e fo llo win g p ro cess co n d it io n s, in p art icu lar based o n p art geo m et ry an d frict io n : – co n t in u o u s exp an sio n an d co m p ressio n o r – o n ly p art ial exp an sio n an d co m p ressio n o r – o n ly calibrat io n Th e d ifferen ces are exp lain ed belo w: Th ese com ponents Fig. 5.2.5 are ch aract erized by a h igh d egree o f d efo rm at io n d u e t o t h e axial m at erial flo w wh ich t akes p lace o ver t h e en t ire co n t o u r o f t h e wo rkp iece. Th ey are exp an d ed an d co m p ressed 408 Hydroforming Fig. 5.2.3 Hydroforming process sequence closing force F Z internal pressure p i horizontal path s filling forming calibration release time Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998 409 Process technology and example applications Fig. 5.2.4 Forces exerted on a tube section w ith a branch T-fitting compression path Fr Fa Ft expansion Ft compression path Fa Fr Fig. 5.2.5 Pure expansioncom- pression operation Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998 d u rin g t h e p ro cess. As a resu lt o f t h e axial m at erial flo w, h igh er d egrees o f d efo rm at io n are p o ssible t h an wh en fo rm in g o n ly by ch an gin g t h e wall t h ickn ess. In so m e cases, lo cal m at erial co m p ressio n resu lt s. Th ese com ponents are ch aract erized by a n u m ber o f lo cally d ist ribu t ed bu lges o ver t h e co m p o n en t len gt h wit h o r wit h o u t in t erm ed iat e ben d s Fig. 5.2.6 . Axial m at erial flo w as a resu lt o f co m p ressio n h as an effect o n ly at t h e co m p o n en t en d s. In t h e case o f sh ap ed elem en t s fo llo win g ben d s o r a m arked bu lge, p o sit io n ed clo se t o t h e h o rizo n t al cylin d ers, o n ly exp an sio n an d calibrat io n t ake p lace, bu t h ard ly an y axial co m - p ressio n . In t h e case o f su ch com ponents, axial co m p ressio n is n o t p o ssible fo r vario u s reaso n s Fig. 5.2.7 . A calibrat io n p ro cess is ap p lied h ere, wh ere- by fo rm in g o n ly t akes p lace m ain ly by ch an gin g t h e wall t h ickn ess.

5.2.3 Fields of application