[en] This thesis develops a new application for the Electromagnetic Forming (EMF) technology: the autobody and white panels hemming operation for aluminium alloys. It is a completely new application for this high speed forming technology so the main variables governing this new hemming process had to be identified. After the identification, a more exhaustive experimental plan was designed to evaluate the possibilities of the EMF technology for hemming applications and the experiments were carried out. Quality parameters like crack appearance or conventional hemming quality defects were selected and analyzed to evaluate the input variables. The main goal of this study is to provide an alternative hemming process for the automotive industry. Due to the required precision and quality on the hemming process and the complexity of the parts, most of the bending, flanging and hemming dies are designed based on experience and on lengthy and costly die tests. Besides, cracking problems arise when hemming light alloys like aluminum. The EMF is a high speed forming technology providing especially good results when used for aluminum alloys. So this study aims to develop and characterize a new and more agile hemming solution that saves time as well as money without damaging the quality of the hem joint, especially when using aluminum alloys. The study can be divided in three parts. The first part is devoted to define and analyze the apparently main input variables of this process. After the first experiments two conclusions come up. The first one establishes the possibility to obtain quality hemmed parts using the EMF technology. The second one is the identification of the main variables. The less influent ones are ruled out. The basic concepts for designing EMF hemming coils were established. The second part is the experimental one. After identifying the main variables of the EMF hemming process, an experimental plan was designed and carried out to develop this new hemming technology. The results were analyzed. Material changes associated to the deformation process were analyzed to finish with this second part. The quality obtained with the conventional hemming processes was matched adjusting the input EMF hemming variables. This quality was established analyzing the process output parameters. This result takes on a higher relevance if we consider that the process time has been reduced and the pre-hemming operation eliminated. A hemmability increase was observed for the alloy used in this thesis. The samples hemmed using the EMF technology have less damage compared to the mechanically hemmed ones for the same final geometry. The inertial effects of the EMF produce a larger distribution of the total deformation around the hemming union instead of concentrating it on the edge. On the third part a new finite element simulation was developed and validated. There is no commercial software simulating the EMF process. The solution reached consists on using an un-coupled simulation method to transfer the electromagnetic pressure from the electromagnetic software to the mechanical software to obtain the deformations. This methodology has been and agile solution for the simulation of the EMF bending and hemming processes giving satisfactory results when comparing with the experimental samples.

[eu] Tesi honetan Konformatu Elektromagnetikorako (EMF) aplikazio berri bat garatzen da: automozio karrozeriako kanpoko piezen kakoztadura ("engatillado") aluminiozko aleazioentzat. Garapen hau guztiz berria izanik, ez dago aurretik egindako ikerketarik. Ondorioz prozesu berri honen bariableak zeintzuk diren ezagutzeko lehen azterketa bat egin da. Bariable nagusiak aukeratu ondoren plan experimentala gauzatu zen EMF-ak kakozteko dituen gaitasunak aztertzeko. Aukeratutako eta ondorioz aztertutako irteerako parametroak kalitatearekin zerikusia dute. Kakoztadura, automozioko kanpo piezei bereziki aplikatutako prozesua denez, exijitutako kalitatea oso altua da. Lan honetan gaur egun automozio industriak dituen kakoztatzeko prozesu mekanikoentzat alternatiba bat bilatzen da. Prozesu mekaniko hauek "puesta a punto"-rako denbora asko behar dute eta gainera arazoak dituzte aluminioa bezelako pisu gutxiko aleazioak kakozterako orduan. EMFa aluminioarekin bereziki ondo funtzionatzen duen abiadura handiko deformazio prozesu bat da. Ikerketa honen helburu nagusia kakozteko prozesu berri eta azkar bat garatu eta karakterizatzean datza. Hau dena aluminiozko piezekin sortzen diren arazoak murriztuz eta beti pieza tipo honi eskatzen zaien kalitate maila mantenduz. Garapen prozesu honen barruan hiru fase nagusi bereiztu dira. Lehenengoan EMFrako aplikazio berri honetan parte hartzen duten bariable desberdinak aztertu dira. Lehenengo fase honetatik bi ondorio atera dira. Lehenengoa EMF teknologiaren baliotasuna ezartzea izan da aluminozko piezak kakoztatzeko. Bigarrena influentzia gehien duten bariableak aukeratzea eta influentzia gutxienekoak baztertzea izan da. Bukaerako kalitate parametroetan influentzia gehien duten bariable horiekin plan experimentala diseinatu da eta bukaeran ondorioak atera dira. Bigarren fasearekin amaitzeko, teknologiaren ondorioz materialeak jasandako aldaketak bai propietate mekanikoetan zein mikroestrukturan aztertu dira. Aztertutako EMF bariableak ondo ajustatuz, prozesu mekanikoekin lorturiko kalitate bereko kakoztadurak lortu dira EMF-z. Kalitate hori prozesu irteerako parámetroak neurtuz ezarri da. Lorpen honek garrantzia handiagoa dauka pre-kakoztadurako operaziorik gabe gauzatu dela kontutan hartzen bada, prozesu denbora murriztuz. Erabilitako aluminiozko aleazioan kakoztadura ahalmenaren haundiagotze bat nabarmendu da EMF teknologia erabiltzerakoan. Bukaerako geometria berbererako, EMF-z kakoztutako piezak min estruktural gutxiago dute mekanikoki kakoztutakoak baino. Fenomeno hau EMF teknologian agertzen diren efektu inertzialen ondorio bat da. Efektu hauek deformazioaren distribuzio desberdin bat egiten dute prozesu mekanikoak baino zona haundiago batetan. Hirugarrengo fasean elementu finitozko simulazio metodo berri bat garatu eta balioztatu da. Gaur egun ez dago software komertzialik EMFa simulatzeko kapazidadea duenik. Ondorioz bi softwarekin desakoplaturiko simulazio metodo bat garatu da. Batak parte elektromagnetikoan sorturiko presioak kalkulatzen ditu eta bigarrenak parte mekanikoan sorturiko deformazioa. Garatutako simulaziozko prozedura hau soluzio azkar eta efiziente bat suertatu da EMF-ren bidezko bai tolestaketa zein kokaztadura prozesuak simulatzeko, lorturiko erantzunak experimentu fisikoetatik oso gertu egonik.