The Experts below are selected from a list of 15 Experts worldwide ranked by ideXlab platform
Henry Valberg - One of the best experts on this subject based on the ideXlab platform.
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Extrusion welding in aluminium Extrusion
International Journal of Materials & Product Technology, 2002Co-Authors: Henry ValbergAbstract:Pressure welds occur in extruded aluminium Profiles either as longitudinal welds (seam welds) or as transverse welds (charge welds). While longitudinal welds only occur in hollow Profiles, transverse welds always occur when the billet is extruded on top of a metal rest left in the die from the previous Extrusion, i.e. in Extrusion of hollows as well as in billet-to-billet Extrusion, and in pre-chamber Extrusion of solid Profiles. Longitudinal welds are formed as the metal streams of different die ports gather behind each die-bridge and join. They extend longitudinally through the profile in the location behind each die web. Transverse welds form as the front end face of each billet pressure welds to the sheared-off back-end face of the Extrusion residue left inside the die from the previous Extrusion. Transverse welds commonly have a tongue-like shape inside the resulting Extrusion and often extend over a large length of the Extrusion. Since Extrusion welds are formed by solid pressure-welding, they are produced with mechanical properties corresponding to the rest of the profile. Unlike fusion welding, there are no filler metal or soft heat-affected zones. But in spite of this, problems in terms of poor weld quality sometimes occur in industrial production of aluminium Profiles. Extrusion welds of insufficient quality contain no voids or cavities and could, therefore, be difficult to detect by non-destructive tests as ultrasonic or x-ray inspection. Since Extrusion welds defects are often unfavourable conditions in the Extrusion process, they can to a large extent be eliminated through corrective measures taken by the extruder. This paper reviews the existing knowledge, as regards formation of Extrusion welds, and defects in such welds. Preventive measures that can be made by the extruder to avoid formation of such defects are also discussed.
Fu Yao - One of the best experts on this subject based on the ideXlab platform.
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Application of butterfly dies in aluminum hollow Profiles Extrusion
Forging and Stamping Technology, 2011Co-Authors: Fu YaoAbstract:A new aluminum Extrusion die named butterfly die was introduced.Designing a butterfly die means giving the bridges an arched shape in place of the typical edged shape.The height in the central part of bridge was lower.The shape of the bridges helps to reduce breakthrough pressure,and to improve the flow behavior of aluminum during Extrusion.The main structures of butterfly die and its features were studied.Examples of butterfly dies practical implication in aluminum alloy hollow Profiles Extrusion were listed,and the Extrusion performance with traditional pothole die was compared.The results show that adopting butterfly die can significantly reduce Extrusion load,improve Extrusion speed and formability of metal.It is an efficiently Extrusion forming technique of aluminum hollow Profiles.
Luca Tomesani - One of the best experts on this subject based on the ideXlab platform.
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Prediction of charge welds in hollow Profiles Extrusion by FEM simulations and experimental validation
The International Journal of Advanced Manufacturing Technology, 2013Co-Authors: Barbara Reggiani, Antonio Segatori, Lorenzo Donati, Luca TomesaniAbstract:In direct Extrusion of aluminum alloys, billets are discretely loaded into the press and joined by the high hydrostatic pressure field. The contamination of the billet-to-billet interface by oxides, dust, or lubricant produces a welded zone (charge weld) with reduced mechanical properties that requires profile discharge. For an efficient material scrapping, both the position of the transition zone and its extent in the profile must be accurately identified. In industrial practice, in relation to a lack of experimental and numerical studies on this specific matter, the determination of the zone to be discarded is still performed mainly by experience or labor-intensive analyses. The aim of the present study is to bridge this gap by investigating the evolution of the charge welds inside an industrial multi-Profiles and determining their exact position and extension by experimental microstructural analyses coupled with comprehensive 3D FE simulations performed with the Arbitrary Lagrangian–Eulerian code HyperXtrude®. Skin and rest defects are also experimentally investigated and a numerical sensitivity study on the influence of the friction model selection is performed. Comparison between numerical and experimental results shows a good agreement both in terms of general trend and exhausting points of the charge welds. The results prove that the FE code is a reliable tool in assisting and driving the die and process design stages, not only for process optimization as reported in literature but also for the scrap length determination. Finally, a process efficiency index is defined and, for the specific case study, it is found to be increased from 82.6 %, as resulting from the actual industrial practice, to a 88.3 % as optimized by the performed coupled experimental and numerical activities.
Leng Zhi - One of the best experts on this subject based on the ideXlab platform.
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CAD/CAM System of Aluminium Profiles Extrusion Die
2002Co-Authors: Leng ZhiAbstract:The characters of CAD/CAM system of Aluminium profile Extrusion dies were discussed.The development and application of CAD/CAM systen were introduced.The guide scheme of CAD/CAM system was given in the paper.On the base of analysis of stress strain field,temperature field and temperature speed changing patterns during Aluminium profile Extrusion,a foundational concept of establishing mathematical models during the Extrusion was proposed.
Barbara Reggiani - One of the best experts on this subject based on the ideXlab platform.
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Prediction of charge welds in hollow Profiles Extrusion by FEM simulations and experimental validation
The International Journal of Advanced Manufacturing Technology, 2013Co-Authors: Barbara Reggiani, Antonio Segatori, Lorenzo Donati, Luca TomesaniAbstract:In direct Extrusion of aluminum alloys, billets are discretely loaded into the press and joined by the high hydrostatic pressure field. The contamination of the billet-to-billet interface by oxides, dust, or lubricant produces a welded zone (charge weld) with reduced mechanical properties that requires profile discharge. For an efficient material scrapping, both the position of the transition zone and its extent in the profile must be accurately identified. In industrial practice, in relation to a lack of experimental and numerical studies on this specific matter, the determination of the zone to be discarded is still performed mainly by experience or labor-intensive analyses. The aim of the present study is to bridge this gap by investigating the evolution of the charge welds inside an industrial multi-Profiles and determining their exact position and extension by experimental microstructural analyses coupled with comprehensive 3D FE simulations performed with the Arbitrary Lagrangian–Eulerian code HyperXtrude®. Skin and rest defects are also experimentally investigated and a numerical sensitivity study on the influence of the friction model selection is performed. Comparison between numerical and experimental results shows a good agreement both in terms of general trend and exhausting points of the charge welds. The results prove that the FE code is a reliable tool in assisting and driving the die and process design stages, not only for process optimization as reported in literature but also for the scrap length determination. Finally, a process efficiency index is defined and, for the specific case study, it is found to be increased from 82.6 %, as resulting from the actual industrial practice, to a 88.3 % as optimized by the performed coupled experimental and numerical activities.
