To Örebro University

oru.seÖrebro University Publications
Change search
Refine search result
2345678 201 - 250 of 2072
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 201.
    Asnafi, Nader
    Swedish Institute for Metals Research, Stockholm, Sweden.
    On Strength, Stiffness and Dent Resistance of Car Body Panels1993Conference paper (Other academic)
  • 202.
    Asnafi, Nader
    Gränges Technology, Finspång, Sweden.
    On stretch and shrink flanging of sheet aluminium by fluid forming1999In: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774, Vol. 96, no 1-3, p. 198-214Article in journal (Refereed)
    Abstract [en]

    In this investigation, vertical stretch and shrink flanging of sheet aluminium by fluid forming are studied experimentally and theoretically. The theoretical part comprises both analytical modelling and finite-element simulations.

    The fracture limit in stretch flanging is determined by the plastic strain ratio, the strain hardening exponent, and the uniform strain. The greater the magnitude of these parameters, the greater will be the fracture limit.

    The maximum applied pressure determines the ’wrinkling’ limit in shrink flanging by fluid forming. The greater is this pressure, the greater ’wrinkling’ limit. This limit is certainly several times greater in magnitude than that in shrink flanging by conventional tools (a rigid punch and die).

  • 203.
    Asnafi, Nader
    Swedish Institute for Metals Research, Stockholm, Sweden.
    On Stretch and Shrink Flanging of Sheet Aluminium by Fluid Forming1996Report (Other academic)
  • 204.
    Asnafi, Nader
    Industrial Development Center/Volvo Cars Body Components, Olofström, Sweden .
    On Stretch and Shrink Flanging of Sheet Aluminium by Fluid Forming1998In: Proceedings, working groups meeting - IDDRG, International Deep Drawing Research Group: Genval, Benelux, June 15 - 16, 1998, 1998Conference paper (Other academic)
  • 205.
    Asnafi, Nader
    Industrial Development Centre, Olofström, Sweden.
    On tool stresses in cold heading of fasteners1999In: Engineering Failure Analysis, ISSN 1350-6307, E-ISSN 1873-1961, Vol. 6, no 5, p. 321-335Article in journal (Refereed)
    Abstract [en]

    In this investigation, attention was focused on the tool stresses that emerge during manufacturing of fasteners. These stresses were studied both experimentally and theoretically. The theoretical part comprised finite-element simulation. This simulation showed that the zone at the die insert profile radius is so heavily loaded that plastic deformation is initiated in this region. In the experimental part, the emerging strains were measured in the region close to the interface between the die insert and the stress ring. The correspondence is good between the theoretical and experimental strains in this region. In spite of this and although 20 fasteners were cold-forged, the die insert did not fracture. Forming at production facilities showed that the die insert cracked after 9080 parts were produced. The results obtained in this investigation and the test conducted at production facilities indicate that high cycle fatigue, and not monotomic rupture, is the main cause of tool fracture in practice.

  • 206.
    Asnafi, Nader
    Örebro University, School of Science and Technology.
    Proceedings of the 2nd International Conference on Material Engineering and Advanced Manufacturing Technology (MEAMT 2018)2018Conference proceedings (editor) (Refereed)
  • 207.
    Asnafi, Nader
    Volvo Car Corporation, Göteborg (and Olofström), Sweden .
    Proceedings of the IDDRG 2008 Conference: Best in class stamping, 16-18 June 2008, Olofström, Sweden2008Conference proceedings (editor) (Other academic)
  • 208.
    Asnafi, Nader
    Örebro University, School of Science and Technology.
    Proceedings of the International Conference on Mechanical, Electric and Industrial Engineering (MEIE2018)2018Conference proceedings (editor) (Refereed)
  • 209.
    Asnafi, Nader
    Volvo Car Corporation, Göteborg (and Olofström), Sweden.
    Proceedings of the international conference on recent advances in manufacture & use of tools & dies and stamping of steel sheets: October 5-6, 2004, Olofström, Sweden2004Conference proceedings (editor) (Other academic)
  • 210.
    Asnafi, Nader
    Örebro University, School of Science and Technology.
    Selective Laser heat Treatment to Tailor the Autobody Part Properties and Improve the Manufacturing Flexibility2019Conference paper (Other academic)
  • 211.
    Asnafi, Nader
    Örebro University, School of Science and Technology.
    Selective Laser heat Treatment to Tailor the Autobody Part Properties and Improve the Manufacturing Flexibility2019Conference paper (Other academic)
    Abstract [en]

    This investigation is focused on the stamping behaviour of boron steel, the properties of which are modified by selective laser heat treatment. Both CO2 and fibre lasers are tested. By using different laser processing parameters, the hardening depth in the 1 mm thick boron steel sheet Boloc 02 is varied. Four routes are tested and verified. The forming operation (in which a so-called flexrail beam is produced) in all four routes is conducted at ambient (room) temperature. The Reference route comprises stamping of the sheet. The GridBlank route starts with selective laser heat treatment of the blank, after which the blank is allowed to cool down, moved to a hydraulic press and stamped. In the GridTube route, the blank is first stamped, after which the part is moved to a laser cell and selectively laser heat treated. The fourth route, the RapidLaser route, is similar to the GridBlank route, but a higher laser speed is used to promote higher total productivity. The GridBlank route results in the highest hardness values and the best shape accuracy. The initial sheet material exhibits a hardness of 200 HV, while the parts produced in the GridBlank route exhibit a hardness of 700 HV.

  • 212.
    Asnafi, Nader
    Swedish Institute for Metals Research, Stockholm, Sweden.
    Springback & Fracture in V-Die Bending: A Literature Survey of Analytical Models1996Report (Other academic)
  • 213.
    Asnafi, Nader
    Gränges Technology, Finspång, Sweden.
    Springback and fracture in v-die air bending of thick stainless steel sheets2000In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 21, no 3, p. 217-236Article in journal (Refereed)
    Abstract [en]

    In this investigation, the attention is focused on the springback and fracture of thick stainless steel sheets. Nine different stainless grades and various thickness are tested. The thinnest sheet is 7.9 mm, whilst the thickest sheet is 31.3 mm. A consistent analytical model is constructed for prediction of the springback, the inner sheet radius prior to and after unloading, and the smallest die width. The springback calculated by this analytical model is in all cases smaller than that found experimentally. The correspondence between theory and practice, is however, very good, although the shift in the position of the neutral axis and thinning are neglected in the theoretical analysis. Fracture did not occur in any of the conducted bending operations. It is commonly assumed that fracture in v-die bending is related to the reduction in the cross-section area at fracture, Z, in tensile testing. Z was greater than 70% for the majority of the studied materials. It is shown that particularly the mode of fracture (fracture through shear bands or by necking) should be studied in future investigations.

  • 214.
    Asnafi, Nader
    VA Automotive AB, Hässleholm, Sweden .
    Sustainable Product and Production Development2015Conference paper (Other academic)
  • 215.
    Asnafi, Nader
    Örebro University, School of Science and Technology.
    The automotive revolution – perspective towards 20302020Conference paper (Refereed)
    Abstract [en]

    What do we do now and where do we wish/need to stand by 2030, when developing and operating/using sustainable products and production systems? Sustainability and digitalisation with a special focus on the development, production, use and recycling/recovery of cars by 2030 are at the focus in this presentation. The current technological and industrial thoughts, wishes, trends, targets, and possibilities and the engineering tools one could use in sustainable design and manufacturing are addressed. Eco-efficiency and eco effectiveness measures in design and manufacturing are described and their impacts illustrated. The expected shift in personal mobility and its technological and industrial impacts will be discussed. Autonomous driving, electrification, and connectivity will be discussed, whilst sustainability is at the focus in this discussion. A holistic approach is used and emission targets, weight reduction, and alternative powertrains and their impacts in material, production, use and recycling/recovery phases in a car’s lifecycle are shown.

  • 216.
    Asnafi, Nader
    Örebro University, School of Science and Technology.
    The Fourth International Conference on Mechanical, Electric and Industrial Engineering (MEIE2021) 22-24 May 2021, Kunming, China2021Conference proceedings (editor) (Refereed)
  • 217.
    Asnafi, Nader
    Örebro University, School of Science and Technology.
    The impact of metal 3D printing of production tools on the lead time, costs, and material efficiency2021Conference paper (Refereed)
    Abstract [en]

    This invited speech deals with the design and manufacturing of production tools & dies for stamping of sheet metal parts and cores (inserts) for injection molding of plastic components. Laser-based Powder Bed Fusion (LPBF) is the metal 3D printing (additive manufacturing) method used in this investigation. Solid and topology optimized stamping tools & dies 3D-printed in DIN 1.2709 by LPBF are certified for stamping of up to 2-mm thick hot-dip galvanized DP600 (dual-phase steel sheet). The punch in a working station in a progressive die used for stamping of 1-mm thick hot-dip galvanized DP600 is 3D-printed in DIN 1.2709, both with a honeycomb inner structure and after topology optimization, with successful results. The core (inserts) of an injection mold for production of sofa clips in Polypropylene Homopolymer (PPH) is 3D-printed in DIN 1.2709, conformal cooling optimized and 3D-printed in Uddeholm AM Corrax, and compared with the same core made conventionally. The cooling and cycle time can be improved, if the injection molding core (inserts) is optimized and 3D-printed in Uddeholm AM Corrax. 3D printing results in a significant lead time reduction and improved tool material efficiency. The manufacturing costs of 3D-printed production tools, dies and cores are higher than the costs of those made conventionally. In the case of injection molding, the total costs (the costs of each produced part) are, however, reduced significantly with a 3D-printed core, since the improved cooling reduces the production cycle time. This contribution accounts for the results obtained in the above-mentioned investigations.

  • 218.
    Asnafi, Nader
    Swedish Institute for Metals Research, Stockholm, Sweden.
    The Influence of In-Process Variation of Blank Holding Force on Deep-Drawability1995In: Leading-Edge Manufacturing Strategies for the Metalforming Industry, Richmond Heights, Ohio, USA: PMA , 1995, p. 965-976Conference paper (Other academic)
  • 219.
    Asnafi, Nader
    Swedish Institute for Metals Research, Stockholm, Sweden.
    The Influence of In-Process Variation of Blank Holding Force on Deep-Drawability1993Report (Other academic)
  • 220.
    Asnafi, Nader
    Örebro University, School of Science and Technology.
    The Second International Conference on Mechanical, Electric and Industrial Engineering, 25–27 May 2019, Hangzhou, China2019Conference proceedings (editor) (Refereed)
  • 221.
    Asnafi, Nader
    Uddeholms AB, Hagfors, Sweden.
    The tool and die materials research and innovation agenda2013In: International Heat Treatment and Surface Engineering, ISSN 1749-5148, Vol. 7, no 3, p. 101-105Article in journal (Refereed)
  • 222.
    Asnafi, Nader
    Örebro University, School of Science and Technology.
    Third International Conference on Mechanical, Electric and Industrial Engineering, 23-25 May 2020, Kunming, China2020Conference proceedings (editor) (Refereed)
  • 223.
    Asnafi, Nader
    Örebro University, School of Science and Technology.
    Tool and Die Making, Surface Treatment, and Repair by Laser-based Additive Processes2021In: Berg- und Huttenmännische Monatshefte (BHM), ISSN 0005-8912, E-ISSN 1613-7531, Vol. 166, no 5, p. 225-236Article in journal (Refereed)
    Abstract [en]

    This paper explores the possibilities to use laser-based additive processes to make, surface treat and repair/remanufacture tools, dies and molds for cold working, hot working, and injection molding. The failures encountered in these applications are described. The materials used conventionally and in the laser additive processes are accounted for. The properties of the tools, dies and molds made by Laser-based Powder Bed Fusion (L-PBF) are as good as and in some cases better than the properties of those made in wrought materials. Shorter cycle time, reduced friction, smaller abrasive wear, and longer life cycle are some of the benefits of L‑PBF and Directed Energy Deposition with powder (DED-p) (or Laser Metal Deposition with powder, LMD‑p, or Laser Cladding, LC). L‑PBF leads to higher toolmaking costs and shorter toolmaking lead time. Based on a review of conducted investigations, this paper shows that it is possible to design and make tools, dies and molds for and by L‑PBF, surface functionalize them by DED-p (LMD‑p, LC), and repair/remanufacture them by DED-p (LMD‑p, LC). With efficient operational performance as the target for the whole tool life cycle, this combination of L‑PBF and DED-p (LMD‑p, LC) has the greatest potential for hot working and injection molding tools and the smallest for cold working tools (due to the current high L‑PBF and DED-p (LMD‑p, LC) costs).

    Download full text (pdf)
    Tool and Die Making, Surface Treatment, and Repair by Laser-based Additive Processes
  • 224.
    Asnafi, Nader
    Swedish Institute for Metals Research, Stockholm, Sweden.
    Tool Design in Cold Heading of Fasteners, Part I: Literature Survey and Analytical Modelling1995Report (Other academic)
  • 225.
    Asnafi, Nader
    Swedish Institute for Metals Research, Stockholm, Sweden.
    Tool Design in Cold Heading of Fasteners, Part II: Finite Element Simulations and Experimental Analysis1996Report (Other academic)
  • 226.
    Asnafi, Nader
    Uddeholms AB, Hagfors, Sweden .
    Tooling & Technologies for Processing Ultra High Strength Materials2011Conference paper (Other academic)
  • 227.
    Asnafi, Nader
    Volvo Car Corporation, Göteborg (and Olofström), Sweden .
    Tooling in manufacturing of car bodies: today & tomorrow2002Conference paper (Other academic)
  • 228.
    Asnafi, Nader
    Uddeholms AB, Hagfors, Sweden .
    Tools & Dies for Processing of Advanced High Strength Sheet Steels2011Conference paper (Other academic)
  • 229.
    Asnafi, Nader
    Volvo Car Corporation, Göteborg (and Olofström), Sweden .
    Tools & Dies in Manufacturing of Car Bodies: Today and Tomorrow2004Conference paper (Other academic)
  • 230.
    Asnafi, Nader
    lnstitutet för Metallforskning, Stockholm, Sweden .
    Tube bending and hydroforming1999In: Svetsaren, a Welding Review, ISSN 0346-8577, Vol. 54, no 1-2, p. 34-35Article in journal (Refereed)
    Abstract [en]

    For the production of low-weight, high-energy absorbent and cost-effective structural automotive components, the hydroforming of aluminium extrusions is now regarded as the only method in many cases. The hydroforming of aluminium extrusions has also demonstrated significant potential in other applications.

  • 231.
    Asnafi, Nader
    Örebro University, School of Science and Technology.
    Tubular Hydroforming and Hydropiercing2019In: Sustainable Material Forming and Joining / [ed] R. Ganesh Narayanan & Jay S. Gunasekera, Boca Raton: CRC Press, 2019Chapter in book (Refereed)
    Abstract [en]

    Hydroforming of tubular components has been known by many other names such as bulge forming of tubes, hydrobulging, internal high-pressure forming, liquid forming of tubular components, etc. Different “hydroforming” methods have been reported earlier. Hydroforming or expansion in an open and in a closed tool (Dohmann and Hartl, 1996), free and die-bound hydroforming (Schäfer Hydroforming, 1996), low, high and sequenced pressure forming (Mason, 1996; VARI-FORM, 1996), and the Rolls–Royce method (Astrop, 1968) are some of the different methods tested, used, and reported so far.

  • 232.
    Asnafi, Nader
    Luleå University of Technology, Luleå, Sweden .
    Återfjädring vid bockning längs krökta linjer1987Report (Other academic)
  • 233.
    Asnafi, Nader
    et al.
    Örebro University, School of Science and Technology.
    Alveflo, Anton
    voestalpine High Performance Metals Sweden AB, Sweden.
    3D Metal Printing of Stamping Tools & Dies and Injection Molds2019In: The 11th Tooling Conference and Exhibition 2019: Communication along the supply chain in the tooling industry, 2019Conference paper (Refereed)
    Abstract [en]

    Design and production of tools, dies and molds are two important steps in the development of new components/products. These steps determine both the lead time (Time-To-Production/-Market) and the size of the investments required to start the production. The lead time for design and production of tools and dies for a new car body and injection molds for plastic components need to be reduced significantly. This paper deals with design, production and business models for 3D metal printing of stamping tools and dies for sheet metal components and injection molds for plastic components. The new possibilities provided by 3D metal printing, such as complex shapes, significant lead time reduction, improved material utilization, reduced weight, better cooling and shorter cycle time are addressed in this paper. Generative design including topology optimization and a couple of powder materials are tested and verified in industrial applications. The impact of 3D metal printing on the business models for the addressed tools/dies/molds are evaluated and described in this paper.

  • 234.
    Asnafi, Nader
    et al.
    Volvo Car Corporation, Göteborg (and Olofström), Sweden.
    Andersson, Roger
    Tubular hydroforming has arrived in Sweden: a smorgasbord of research, design, and application2001In: The Tube & Pipe Journal, Vol. 12, no 2, p. 13-17Article in journal (Refereed)
  • 235.
    Asnafi, Nader
    et al.
    Örebro University, School of Science and Technology.
    Andersson, Roger
    Persson, Martin
    Liljengren, Magnus
    Comparison of Lightweight Solutions: Low Cost Production Process for High Strength Boron Steel Components2016Conference paper (Other academic)
  • 236.
    Asnafi, Nader
    et al.
    VA Automotive AB, Hässleholm, Sweden .
    Andersson, Roger
    Duroc Special Steel, Luleå, Sweden.
    Persson, Martin
    Duroc Laser Coating, Luleå, Sweden.
    Liljengren, Magnus
    Industrial Development Center, Olofström, Sweden .
    Tailored boron steel sheet component properties by selective laser heat treatment2016Conference paper (Refereed)
    Abstract [en]

    This investigation is focused on the stamping behaviour of boron steel, the properties of which are modified by selective laser heat treatment. Both CO2 and fibre lasers are tested. By using different laser processing parameters, the hardening depth in the 1 mm thick boron steel sheet Boloc 02 is varied. Four routes are tested and verified. The forming operation (in which a so-called flexrail beam is produced) in all four routes is conducted at ambient (room) temperature. The Reference route comprises stamping of the sheet. The GridBlank route starts with selective laser heat treatment of the blank, after which the blank is allowed to cool down, moved to a hydraulic press and stamped. In the GridTube route, the blank is first stamped, after which the part is moved to a laser cell and selectively laser heat treated. The fourth route, the RapidLaser route, is similar to the GridBlank route, but a higher laser speed is used to promote higher total productivity. The GridBlank route results in the highest hardness values and the best shape accuracy. The initial sheet material exhibits a hardness of 200 HV, while the parts produced in the GridBlank route exhibit a hardness of 700 HV.

  • 237.
    Asnafi, Nader
    et al.
    Swedish Institute for Metals Research, Stockholm, Sweden .
    Ekstrand, Gunnar
    Springback and Fracture in V-Die Air Bending of Thick Stainless Steel Sheets1998Report (Other academic)
  • 238.
    Asnafi, Nader
    et al.
    Swedish Institute for Metals Research, Stockholm, Sweden .
    Gabrielson, Per
    Formability of Stainless Steel and Commercially Pure Titanium Sheets in Plate Heat Exchanger Applications1997Report (Other academic)
  • 239.
    Asnafi, Nader
    et al.
    Volvo Car Corporation, Göteborg (and Olofström), Sweden .
    Hjelm, Sven
    Scania.
    Holmgren, Björn
    Scania.
    Malmsköld, Lennart
    Saab Automobile.
    Granström, Magnus
    AB Volvo.
    Svenningstorp, Johan
    AB Volvo.
    Mellgren, Henry
    FKG.
    2015 Sustainable Manufacturing Systems Capable of Producing Innovative Environmentally Friendly and Safe Products: R&D program proposal to secure competitive vehicle and powertrain production in Sweden2008Report (Other academic)
    Download full text (pdf)
    2015 Sustainable Manufacturing Systems Capable of Producing Innovative Environmentally Friendly and Safe Products
  • 240.
    Asnafi, Nader
    et al.
    Volvo Cars Body Components, Olofström, Sweden.
    Johansson, T.
    Volvo Cars Body Components, Olofström, Sweden.
    Miralles, M.
    Volvo Cars Body Components, Olofström, Sweden.
    Ullman, A.
    Volvo Cars Body Components, Olofström, Sweden.
    Laser surface-hardening of dies for cutting, blanking or trimming of uncoated DP6002004In: Proceedings of the International Conference on Recent Advances in Manufacture and Use of Tools and Dies and Stamping of Steel Sheets / [ed] Nader Asnafi, Olofström: Vovo Cars , 2004, p. 193-214Conference paper (Refereed)
    Abstract [en]

    In this study, the methods used to harden trim dies were at the focus. Laser surface-hardening was compared to induction- and through-hardening for small and medium-size series production. The sheet materials used were 1.2 mm thick uncoated Docol 600DP and 1.95 mm thick uncoated Docol 600DL The die materials tested were Fermo, Canmo and Sleipner. This investigation showed that the optimum laser-hardening parameters must be established for each trim die material. The trim die in laser-hardened Sleipner exhibits the smallest wear, whilst the trim die in induction-hardened Fermo displays the largest wear in the semi-industrial phase of this study. The magnitude of this largest wear is, however, very small. The trim die in induction-hardened Fermo managed 100 000 strokes without any problem. The dimensional changes after laser hardening are very small. The burr height is very small, regardless of how the trim die is hardened. In this study, two sets of production trim dies were manufactured and set up. This production trim dies are used in the manufacture of V70 B-pillar Left and Right Laser hardening resulted in a lead time reduction by 5 labour days. However, the Tool & Die unit estimates that the lead time reduction obtained with laser hardening should be around 10 days under normal conditions. The cost analysis conducted by the Tool & Die unit shows that the manufacturing costs are reduced by 6%, if laser-hardening is selected. These production trim dies are and will be monitored continuously. As this paper is being written, these dies have been subject to 50 000 strokes.

  • 241.
    Asnafi, Nader
    et al.
    Volvo Cars Body Components, Olofström, Sweden.
    Kjellsson, K.
    Volvo Cars Body Components, Olofström, Sweden.
    Johansson, T.
    Volvo Cars Body Components, Olofström, Sweden.
    Blanking, stamping and trimming die experiences at volvo cars2004In: Proceedings of the International Conference on Recent Advances in Manufacture & Use of Tools & Dies and Stamping of Steel Sheets / [ed] Nader Asnafi, Olofström: Volvo Cars , 2004, p. 263-274Conference paper (Refereed)
    Abstract [en]

    During the past years, large efforts have been made at Volvo Cars to establish a scientific and systematic approach to selection of die materials, hardening methods and surface treatments/coatings. These efforts were initiated, since both new higher strength sheet materials and new die materials with better performance were introduced. Both these higher strength sheet materials and higher performance die materials needed to be industrialized. At the same time, the die manufacturing and maintenance costs must be reduced. A relationship must also be established between the die materials, hardening methods and surface treatments/coatings selected on one side and the targeted volume sizes on the other. In this paper, some of the industrial cases studied at Volvo Cars will be presented. This study is, however, not completed yet The dies described in this paper (along with other dies) have been and will be monitored continuously. The authors have chosen to focus on the technology rather than the economy, particularly since the primary purpose of this paper is to share information with other technicians and discuss the feasibility of different technical solutions. Six blanking/trimming dies and seven stamping (forming) dies are presented in this paper.

  • 242.
    Asnafi, Nader
    et al.
    Industrial Development Centre, Olofström, Sweden.
    Langstedt, G.
    Linlan Composite AB, Staffanstorp, Sweden.
    Andersson, C.-H.
    Dept. of Prod. and Mat. Engineering, Lund Inst. Technol., P.O. B., Lund, Sweden; IFP, Swed. Inst. Fibre Poly. Res., P.O., Mölndal, Sweden.
    Östergren, N.
    Industrial Development Centre, Olofström, Sweden.
    Håkansson, T.
    Industrial Development Centre, Olofström, Sweden.
    New lightweight metal-composite-metal panel for applications in the automotive and other industries2000In: Thin-walled structures, ISSN 0263-8231, E-ISSN 1879-3223, Vol. 36, no 4, p. 289-310Article in journal (Refereed)
    Abstract [en]

    A new lightweight metal-composite-metal (MCM) panel is developed. This panel consists of two layers of 0.2-mm thick stainless steel sheet with a layer of woven fabric (semi-flexible composite) in between. The stiffness and the dent resistance of this MCM-panel are compared to those of corresponding panels pressed in 1-mm thick aluminum, 0.8-mm thick carbon steel and 0.8-mm thick stainless steel sheets. Compared to the aluminum panel, the MCM-panel exhibits a slightly smaller stiffness. However, the MCM-panel displays a larger dent resistance than the aluminum and the carbon steel panels. The new panel is 46% heavier than the aluminum panel. However, it is 60% lighter than the carbon and stainless steel panels. This new panel is expected to have many applications in manufacturing of parts for car, train and bus bodies, appliances and household machines. Machine chassis and air cargo containers are other examples of products, in which the new panel can be used. Production of the new panel requires that the tools be heated. The cycle time is short, since a newly developed and patented method for ultra-rapid heating of tools has been used in this study. The production is economical, since the cycle times is short and recycled fibres can be used. The production process is not completely optimized yet. However, the conducted experiments show that the panel stiffness and dent resistance are benefitted, if the tool pressure applied during the heating is low.

  • 243.
    Asnafi, Nader
    et al.
    Swedish Institute for Metals Research, Stockholm, Sweden .
    Larsson, Mats
    On Characterization of Cold Forging Properties of Steels: a New Testing Method1994Report (Other academic)
  • 244.
    Asnafi, Nader
    et al.
    Volvo Car Corporation, Olofström, Sweden.
    Lassl, G.
    Volvo Car Corporation, Olofström, Sweden.
    Olsson, B.
    Sapa Profiles.
    Nilsson, T.
    Sapa Profiles.
    Theoretical and experimental analysis of hydropiercing2003In: SAE technical paper series, ISSN 0148-7191, article id 2884Article in journal (Refereed)
    Abstract [en]

    In this study, hydropiercing after hydroforming and prior to unloading was investigated. The primary purpose of this study was to investigate how the used hydropiercing method and the selected material and process parameters affect the hole quality. Hydropiercing inwards, hydropiercing by folding the ’scrap’ piece inwards and hydropiercing outwards were tested. The tube material was extruded AA6063-T4. The tube diameter and wall thickness were 107 mm and 2.5 mm respectively. Straight 1110-mm long tubes of this material were first hydroformed at 1300 bar and then hydropierced. Assuming that the largest (in magnitude) acceptable deflection at the hole edge is 0.2 mm, hydropiercing inwards at ≥ 1300 bar yield the best hole quality. However, the remaining scrap piece (in the tube) causes a handling problem that must be solved.

  • 245.
    Asnafi, Nader
    et al.
    Örebro University, School of Science and Technology. Zhejiang Chuangge Technology, Zhuji, China.
    Leitner, Harald
    Voestalpine Böhler Edelstahl GmbH & CoKG, Linz, Austria.
    Hackl, Gerhard
    ASMET, Leoben, Austria.
    Editorial2022In: Berg- und Huttenmännische Monatshefte (BHM), ISSN 0005-8912, E-ISSN 1613-7531, Vol. 167, no 9, p. 407-407Article in journal (Refereed)
  • 246.
    Asnafi, Nader
    et al.
    Luleå University of Technology, Luleå, Sweden .
    Magnusson, Claes
    Aluminiumplåt: möjligheter att påverka formningsegenskaperna1988In: Verkstadstidningen, ISSN 0346-6434, no 9Article in journal (Refereed)
  • 247.
    Asnafi, Nader
    et al.
    Sapa Profiles/Sapa Technology, Finspång, Sweden.
    Nilsson, T.
    Sapa Profiles/Sapa Technology, Finspång, Sweden.
    Lassl, G.
    Volvo Car Corp..
    Automotive tube bending and tubular hydroforming with extruded aluminium profiles2000In: SAE technical paper series, ISSN 0148-7191, article id 2670Article in journal (Refereed)
    Abstract [en]

    Side Member Left and Side Member Right, which go from bumper to bumper, were at the focus in the present study. These side members were produced using straight round (hollow with a circular cross-section) extruded aluminium profiles as tube material. The tubes were bent and hydroformed. Rotary-draw bending yielded the best result. A spread within 8 mm after bending was found to be acceptable provided that the bent tube was hydroformed with a high maximum internal pressure (1300 bars in this study). Pressure-assisted tool (hydroforming tool) closure should be preferred. Such a tool closure prevents formation of buckles, which may be difficult to straighten out completely during hydroforming. Planeness and parallelity of the press tables and adapters play a significant role, as far as the spread and inplaneness of hydroformed components are concerned. The hydroforming tool must be matched in the press that actually will be used. Proper evacuation (of particularly air) is essential, especially in long hydroforming tools. All cross sections must be deformed at least 2% (average perimeter enlargement), if the hydroformed components are to exhibit a reasonable spread. The critical (fracture) cross-sections predicted by finite-element simulation correspond to those found in practical tests. However, the finite-element simulation was not able to predict formation of wrinkles at the tube ends caused by excessively large strokes. Such wrinkles were obtained in practice.

  • 248.
    Asnafi, Nader
    et al.
    Volvo Car Corporation, Olofström, Sweden.
    Nilsson, Tomas
    Sapa Profile Bending, Vetlanda, Sweden.
    Lassl, Gunnar
    Volvo Car Corporation, Göteborg, Sweden.
    Tubular hydroforming of automotive side members with extruded aluminium profiles2003In: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774, Vol. 142, no 1, p. 93-101Article in journal (Refereed)
    Abstract [en]

    Side member left and side member right, which go from bumper to bumper in a car body, were at the focus in the present study. These side members were produced using straight round (hollow with a circular cross-section) extruded aluminium profiles as tube material. The tubes were bent and hydroformed. Rotary-draw bending yielded the best result. A spread within 8mm after bending was found to be acceptable provided that the bent tube was hydroformed with a high maximum internal pressure (1300bar in this study). Pressure-assisted tool closure (hydroforming tool) should be preferred. Such a tool closure prevents formation of buckles, which may be difficult to straighten out completely during hydroforming. Planeness and parallelity of the press tables and adapters play a significant role, as far as the spread and inplaneness of hydroformed components are concerned. The hydroforming tool must be matched in the press that actually will be used. Proper evacuation (of particularly air) is essential, especially in long hydroforming tools. All cross-sections must be deformed at least 2% (average perimeter enlargement) if the hydroformed components are to exhibit a reasonable spread. The critical (fracture) cross-sections predicted by finite-element simulation corresponded to those found in practice. However, the finite-element simulation was not able to predict formation of wrinkles at the tube ends caused by excessively large strokes. Such wrinkles were obtained in practice.

  • 249.
    Asnafi, Nader
    et al.
    Volvo Car Corporation, Göteborg (and Olofström), Sweden .
    Ocklund, Johnny
    Lassl, Gunnar
    Tubular hydroforming of side members and crash beams: a study from the perspective of Volvo Cars2002In: Information Technology, Global Environment and Sheet Metal Forming: Proceedings of the 22nd Biennial Congress, 2002, p. 289-298Conference paper (Other academic)
  • 250.
    Asnafi, Nader
    et al.
    Örebro University, School of Science and Technology.
    Rajalampi, Jukka
    RISE IVF, Olofström, Sweden.
    Aspenberg, David
    DYNAmore Nordic, Linköping, Sweden .
    Design and Validation of 3D-Printed Tools for Stamping of DP6002019In: 38th International Deep Drawing Research Group Annual Conference, IDDRG 2019 / [ed] van den Boogaard, T; Hazrati, J; Langerak, N, Institute of Physics Publishing (IOPP), 2019, Vol. 651, article id 012010Conference paper (Refereed)
    Abstract [en]

    This paper is focused on automotive stamping tools & dies and the impact of 3D metal printing on design and production of such tools & dies. Forming (U-bend) and trimming/cutting/blanking tools & dies designed both conventionally and by topology optimization were 3D-printed, using Laser-based Powder Bed Fusion (LPBF), in the maraging steel DIN 1.2709. These 3D-printed tools were then used to form (U-bend) and trim/cut/blank 2-mm thick hot-dip galvanized DP600. An approval of the forming tool required that 50,000 U-bends were formed in 2-mm thick DP600 without any surface scratches on the sheet metal part. An approval of the trimming/cutting/blanking tool required 100,000 trimming strokes with this tool, where the maximum (sheet metal) burr height was lower than 0.2 mm (lower than 10% of the sheet thickness (2 mm in this study)). The 3D-printed forming and trimming/cutting/blanking tools & dies - both the conventionally designed and the topology optimized versions – managed the criteria mentioned above and were therefore approved. The approval means that these concepts can now be used to make production stamping tools and dies. This paper describes the topology optimization, the forming & trimming/cutting/blanking testing, the results yielding an approval of the 3D-printed tool concepts, and the 3D-printed production tools for stamping of DP600.

2345678 201 - 250 of 2072
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf