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- 검색키워드
- 저자 : Luis Norberto López de Lacalle (검색결과 4 건)
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Felipe Marin,Adriano Fagali de Souza,Alexandre Mikowski,Luís Henrique Guarnieri Fontanella,Paulo Soares,Luis Norberto López de Lacalle 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.10 No.4
The hybrid manufacturing procedure of combining an initial machining process and a posterior laser powder bed fusion (LPBF) process opens a new range of possibilities for manufacturing complex parts, promising to reduce both costs and printing time. Hence, the first portion of the part might be manufactured by machining, which is used as the substrate for the LPBF. Different manufacturing processes produce a melting interface zone (MIZ) that can affect the mechanical properties of hybrid parts. This work investigates the properties of the MIZ in hybrid parts. The influence of the energy density of the LPBF process on the interface zone and the mechanical properties of the final hybrid part were assessed. The different tests showed high-quality interphase even with low energy density, with a melting depth of up to 0.3 mm. Tomography analysis showed no pores in the MIZ and the increase in pore number with the scanning speed, reducing the UTS of the hybrid samples from 8 to 42% in relation to machined Corrax®. Additionally, a test piece for injection molding was produced by this new hybrid manufacturing process. The results showed that the costs and manufacturing time were reduced by about 50%, showing a potential application of hybrid manufacturing in such applications. Besides, this work identifies a limitation of the hybrid manufacturing approach using LPBF machines which are not equipped with a system to identify the substrate coordinate system. The present study develops an operational method to identify the coordinate system in order to ease the referencing of the pre-machined substrate within the machine platform.
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Investigation of thermal-related effects in Hot SPIF of Ti-6Al-4V alloy
Mikel Ortiz,Mariluz Penalva,Edurne Iriondo,Luis Norberto López de Lacalle 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.7 No.2
The present work focuses on a new approach to hot form hard-to-work materials by Single Point Incremental Forming (SPIF) technology using a global heating of the sheet. A set of trials was carried out in order to identify the optimum temperature cycles to minimize geometric distortions associated to each process stage on the fabrication of parts made of Ti–6Al–4V. On the one hand, heating trials allowed defining the optimal procedure to improve the temperature distribution homogeneity along the sheet and consequently to minimize its thermal distortion previous to the forming stage. On the other hand, the influence of both working temperature and the applied cooling on the geometric accuracy was evaluated by means of SPIF trials. For this purpose, a generic asymmetric design with typical aeronautical features was used. These trials pointed out that high forming temperatures allow reducing significantly the material springback whereas a controlled cooling (with an intermediate stress relief treatment) minimizes both the distortion of the part during the cooling and the mechanical stresses accumulated on the clamping system. Furthermore, the work includes a post-forming material evaluation to determinate the influence of the employed processing conditions on microcracks, alpha-case layer, microstructure and hardness.
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Nozzle Design for Combined Use of MQL and Cryogenic Gas in Machining
Octavio Pereira,Adrián Rodríguez,Joaquín Barreiro,Ana Isabel Fernández-Abia,Luis Norberto López de Lacalle 한국정밀공학회 2017 International Journal of Precision Engineering and Vol.4 No.1
Nowadays, the need for not only technically but also environmentally efficient machining processes is increasing. In this context, the reduction of oil emulsion type coolants used during machining of aeronautical engine components supposes a great challenge. In this paper, a novel approach based on the design, optimization and validation of a nozzle adaptor combining cryogenic technology and minimum quantity lubrication systems is proposed. The proposed work also deals with the aim of obtaining a cost-effective process. Thus, CO2 flow and velocity was optimized in this line. Theoretically-based analysis were performed and compared with computational fluid dynamics (CFD) simulations and with real experimental tests as well. Once optimizing these key factors, two nozzle adaptors were designed and simulated by CFD. Different geometries were tested looking for the most efficient design. Finally, to obtain a feasible industrial product, the developed nozzle was tested as a CryoMQL demonstrator comparing with other lubri-coolant techniques during milling Inconel 718. Results show a successful balance between technical and environmental issues using this technology when milling aeronautical alloys.
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Simulation of Cryo-cooling to Improve Super Alloys Cutting Tools
Octavio Pereira,Adrián Rodríguez,Amaia Calleja-Ochoa,Ainhoa Celaya,Luis Norberto López de Lacalle,Asier Fernández-Valdivielso,Haizea González 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.9 No.1
Improve machining processes from an environmental point of view is a hot topic currently. In this line, cryogenics CO 2 is presented as a solution to substitute conventional oil emulsions. However, to be applied industrially, it is needed to control CO 2 flow rate with the aim of reducing CO 2 consumption to reach what it is known as ECO 2 -performance (economy + ecology). Then, despite currently CO 2 cooling technique is used as external coolant, it is needed to improve its use—especially in milling processes—for achieving this goal. In line with this, in this paper is presented the use of CO 2 as tool internal coolant as a solution to optimize its use. For checking its suitability, a study based on computer fluid dynamics with a new cryogenic tool channels design and experimental tests were carried out for analyzing the differences between using CO 2 as internal and external coolant with the aim of improving the use of cryogenic gases during Inconel 718 milling processes. The results show that the use of CO 2 as internal coolant improves the current milling process not only from environmental point of view but also economic and technical, bringing CO 2 cryogenic technology closer to industrial milling conditions.
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