Browsing by Author "Arregi, B."
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Item Automatic welding systems for large ship hulls(2012) Arregi, B.; Granados, S.; Hascoet, J. Y.; Hamilton, K.; Alonso, M.; Ares, E.; EXTREMATWelding processes represents about 40% of the total production time in shipbuilding. Although most of the indoor welding work is automated, outdoor operations still require the involvement of numerous operators. To automate hull welding operations is a priority in large shipyards. The objective of the present work is to develop a comprehensive welding system capable of working with several welding layers in an automated way. There are several difficulties for the seam tracking automation of the welding process. The proposed solution is the development of a welding machine capable of moving autonomously along the welding seam, controlling both the position of the torch and the welding parameters to adjust the thickness of the weld bead to the actual gap between the hull plates.Item A new friction stir welding based technique for corner fillet joints: Experimental and numerical study(2010-04) Buffa, G.; Fratini, L.; Arregi, B.; Penalva, M.; EXTREMAT; FABRIC_INTELFriction stir welding (FSW) is an energy efficient and environmentally friendly (no fumes, noise, or sparks) welding process, during which the sheets are welded together in a solid-state joining process. FSW is mature for simple configurations but a significant lack of knowledge is found when dealing with different designs such as T-sections, corner welds and box sections. The present work explores the feasibility of producing corner fillet geometries using FSW. Although such a kind of geometry has traditionally been considered unfeasible for the process, it seems to have a great potential to be used for T-joint configurations, a recurrent design pattern in transport applications. A specific tool has been developed and a set of welds has been produced with it. The process has been analysed by both micro and macro observations and a dedicated numerical model tuned by comparison of the thermal histories experimentally measured by embedded thermocouples. According to the obtained results, the proposed model is able to represent a useful design tool for the process. Main problem pending to be solved is how to avoid the formation of a tunnel defect in the weld centre line due to a suck effect of the tool on the stirred material.Item Parameter optimization for mould and die recovering using laser cladding(2009) Tabernero, I.; Lamikiz, A.; Ukar, E.; Arregi, B.; Figueras, J.; Soriano, C.; EXTREMATIn the last years the laser cladding has become an important technology that has been studied by several industries as automotive or aeronautical. Therefore, although this technology was used initially for coatings, actually it is being used for repairing or even direct manufacturing of high added value parts. In this paper, the application of laser cladding for repairing a GGG70L stamping die is presented. The first step is to present the methodology used to obtain the optimum conditions for AISI 316L stainless steel clads on structural steel (DIN C45). The next section shows a deeper study about the capacity of the process to fill standard geometries on DIN C45 and DIN 1.2379. Finally, a nodular cast iron GGG70L stamping die is repaired using laser cladding process. The parameters and strategy used for the repairing have been obtained on previous sections. Furthermore, in the final section a powder concentration model is presented as the first step to create a complete model that simulate the three stages of laser cladding: interaction between powder and laser beam, creation of melt pool and generation of clad geometry.Item Reluctance sensor for penetration depth control in friction stir welding(2013-01) García-Arribas, A.; Feutchwanger, J.; Fernández, E.; Penalva, M.; Arregi, B.; FABRIC_INTEL; EXTREMATWe propose a detailed design of a reluctance position sensor for determining the penetration of the welding tool in a friction stir welding machine. It functions by sensing the variations of the inductance of a coil due to the changes in the gap of the magnetic circuit created by the welding tool and the working bench. Intensive finite element simulations have been performed to decide the best configuration, including the geometry of the sensor, the winding of the coil and the properties of the magnetic materials. Static measurements in a functional prototype demonstrate the validity of the method and the design.