[en] This research work is based on two strategic lines at medium and long term: the use of lightweight materials and the development of innovative processes that improve the forming of these materials. In this thesis, within the lightweight materials family, some of the aluminium alloys with best mechanical properties have been selected due to the attractive characteristics they present (high reciclability, elevated resistance/weight ratio, excellent corrosion resistance, good soldability), which make the trend in aluminium compounds fabrication in constant increase. Most of this components need the forming technologies for their elaboration. In order to increase the reduced deformation levels obtained at room temperature with these alloys, the innovative actuation line to assist the forming processes with heat has been chosen. Sheet hydroforming technology has been selected as the innovative technology where this work is centred in, because of its advantages as, the improvement of the part resistance and as a result the reduction of the weight, the very good dimensional and superficial precision of the components, the friction reduction induced higher deformation levels, thickness distribution enhancement and tool costs reduction. The objective of this work has been to develop the warm sheet hydroforming technology for aluminium alloys. The creation of knowledge that will permit the fabrication of high added value aluminium alloy parts with the application of this technology has been pretended. To reach this goal, a preliminary aluminium alloys uniaxial warm characterization study has been completed, necessary to define the working conditions to optimize the forming of the materials. Secondly, a warm sheet hydroforming prototype has been designed and set up. The closing system and the hydraulic system of the installation are innovative, hence, both of them have been patented. Moreover, an automatic strain measurement optical system has been developed. Next, the study has been focused on the biaxial characterization of the material. Besides, the Forming Limit Diagrams (FLDs) of the alloys have been obtained at warm temperatures with the purpose of using the resulting data as a failure criterion tool. In a further stage a prototype part has been formed to evaluate the obtained results with the warm sheet hydroforming technology in comparison to those obtained at room temperature. Finally, a numerical model for the warm sheet hydroforming of aluminium alloys has been created. The results obtained with models based on uniaxial and biaxial characterization have been compared. The developed model has been evaluated with the prototype part forming experimental data.

[eu] Epe ertain eta luzera lerro estrategikotzat definitzen diren bi lan arlotan oinarritzen da ikerkuntza lan hau: material arinen erabilera eta hauen konformatzea errazten duten fabrikazio prozesu berritzaileen garapena. Material arinen taldearen barruan, ezaugarri mekaniko hobereneko aluminiozko aleazio batzuk aztertu dira tesi honetan. Izan ere, hauen ezaugarri deigarriei esker (berziklagarritasuna, erresistentzi/pisu ratio altua, korrosio erresistentzia ezinhobea, soldatzeko egokiera ona) aluminiozko aleazioz ekoizten diren pieza kopurua igoera etengabean dago. Horrelako osagai gehienek deformazio teknologien beharra dute haien fabrikaziorako. Giro tenperaturan horrelako aleazioek duten deformatzeko gaitasun murritzari aurre egiteko, fabrikazio prozesuak beroarekin laguntzeko lan ildo berritzaileari ekitea erabaki d. Txapazko hidrokonformaketa aukeratu da lan honetarako teknologia ardatz bezala, piezen erresistentziaren hobetzea eta ondorioz pisuaren murrizketa ematen duelako, osagaien dimentsio eta gainazal doitasun oso ona posible egiten duelako, marruskadura murriztearen ondorioz lortzen den deformagarritasun maila handiagoa, lodieren banaketan hobekuntza eta erreminta kostuen murrizketa ematen dituelako. Ondorioz, tesi honen helburua aluminiozko aleazioen hidrokonformaketa beroan garatzea izan da. Horrela, etorkizunean erabili ahal izango den ezagutza sortuz aluminiozko pieza konplexuak garatu ahal izatea nahi izan da. Horretarako, txapazko aluminio aleazioen karakterizazio uniaxialaren inguruko ikerketa egin da, beharrezkoa baita lanerako baldintza egokienak topatzeko. Ondoren, txapazko berorako hidrokonformaketa makina bat diseinatu eta martxan jarri da. Instalazioaren itxiera mekanismoa eta sistema hidraulikoa berritzaileak direnez patentatuak izan dira. Gainera, piezen deformazioak era automatikoan neurtzeko sistema optikoa sortu da. Garatutako instalazioa egiaztatu ondoren, aleazioak prozesuko baldintzapean karakterizatu dira, hau da, tentsio egoera biaxialpean. Hara eta gehiago, deformagarritasun muga diagramak (FLDak) kalkulatu dira tenperatura epeletan, hauste irizpide bezala erabili ahal izateko. Pieza prototipo bat ere konformatu da, beroko hidrokonformaketa prozesuaren emaitzak giro tenperaturako hidrokonformaketa bidez ekoiztutakoekin alderatu ahal izateko. Azkenik, beroko txapazko aluminio aleazioen hidrokonformaketarako zenbakizko simulazio eredu bat garatu da. Karakterizazio uniaxialak eta biaxialak kontuan izanik bi eredu desberdin konparatu dira eta lortutako emaitzak pieza prototipoaren esperimentazio datuekin baieztatu dira.