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  • 151.
    Asnafi, Nader
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Proceedings of the International Conference on Mechanical, Electric and Industrial Engineering (MEIE2018)2018Konferanseproceedings (Fagfellevurdert)
  • 152.
    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, Sweden2004Konferanseproceedings (Annet vitenskapelig)
  • 153.
    Asnafi, Nader
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Selective Laser heat Treatment to Tailor the Autobody Part Properties and Improve the Manufacturing Flexibility2019Konferansepaper (Annet vitenskapelig)
  • 154.
    Asnafi, Nader
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Selective Laser heat Treatment to Tailor the Autobody Part Properties and Improve the Manufacturing Flexibility2019Konferansepaper (Annet vitenskapelig)
    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.

  • 155.
    Asnafi, Nader
    Swedish Institute for Metals Research, Stockholm, Sweden.
    Springback & Fracture in V-Die Bending: A Literature Survey of Analytical Models1996Rapport (Annet vitenskapelig)
  • 156.
    Asnafi, Nader
    Gränges Technology, Finspång, Sweden.
    Springback and fracture in v-die air bending of thick stainless steel sheets2000Inngår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 21, nr 3, s. 217-236Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 157.
    Asnafi, Nader
    VA Automotive AB, Hässleholm, Sweden .
    Sustainable Product and Production Development2015Konferansepaper (Annet vitenskapelig)
  • 158.
    Asnafi, Nader
    Swedish Institute for Metals Research, Stockholm, Sweden.
    The Influence of In-Process Variation of Blank Holding Force on Deep-Drawability1995Inngår i: Leading-Edge Manufacturing Strategies for the Metalforming Industry, Richmond Heights, Ohio, USA: PMA , 1995, s. 965-976Konferansepaper (Annet vitenskapelig)
  • 159.
    Asnafi, Nader
    Swedish Institute for Metals Research, Stockholm, Sweden.
    The Influence of In-Process Variation of Blank Holding Force on Deep-Drawability1993Rapport (Annet vitenskapelig)
  • 160.
    Asnafi, Nader
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    The Second International Conference on Mechanical, Electric and Industrial Engineering, 25–27 May 2019, Hangzhou, China2019Konferanseproceedings (Fagfellevurdert)
  • 161.
    Asnafi, Nader
    Uddeholms AB, Hagfors, Sweden.
    The tool and die materials research and innovation agenda2013Inngår i: International Heat Treatment and Surface Engineering, ISSN 1749-5148, Vol. 7, nr 3, s. 101-105Artikkel i tidsskrift (Fagfellevurdert)
  • 162.
    Asnafi, Nader
    Swedish Institute for Metals Research, Stockholm, Sweden.
    Tool Design in Cold Heading of Fasteners, Part I: Literature Survey and Analytical Modelling1995Rapport (Annet vitenskapelig)
  • 163.
    Asnafi, Nader
    Swedish Institute for Metals Research, Stockholm, Sweden.
    Tool Design in Cold Heading of Fasteners, Part II: Finite Element Simulations and Experimental Analysis1996Rapport (Annet vitenskapelig)
  • 164.
    Asnafi, Nader
    Uddeholms AB, Hagfors, Sweden .
    Tooling & Technologies for Processing Ultra High Strength Materials2011Konferansepaper (Annet vitenskapelig)
  • 165.
    Asnafi, Nader
    Volvo Car Corporation, Göteborg (and Olofström), Sweden .
    Tooling in manufacturing of car bodies: today & tomorrow2002Konferansepaper (Annet vitenskapelig)
  • 166.
    Asnafi, Nader
    Uddeholms AB, Hagfors, Sweden .
    Tools & Dies for Processing of Advanced High Strength Sheet Steels2011Konferansepaper (Annet vitenskapelig)
  • 167.
    Asnafi, Nader
    Volvo Car Corporation, Göteborg (and Olofström), Sweden .
    Tools & Dies in Manufacturing of Car Bodies: Today and Tomorrow2004Konferansepaper (Annet vitenskapelig)
  • 168.
    Asnafi, Nader
    lnstitutet för Metallforskning, Stockholm, Sweden .
    Tube bending and hydroforming1999Inngår i: Svetsaren, a Welding Review, ISSN 0346-8577, Vol. 54, nr 1-2, s. 34-35Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 169.
    Asnafi, Nader
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Tubular Hydroforming and Hydropiercing2019Inngår i: Sustainable Material Forming and Joining / [ed] R. Ganesh Narayanan & Jay S. Gunasekera, Boca Raton: CRC Press, 2019Kapittel i bok, del av antologi (Fagfellevurdert)
    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.

  • 170.
    Asnafi, Nader
    Luleå University of Technology, Luleå, Sweden .
    Återfjädring vid bockning längs krökta linjer1987Rapport (Annet vitenskapelig)
  • 171.
    Asnafi, Nader
    et al.
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Alveflo, Anton
    voestalpine High Performance Metals Sweden AB, Sweden.
    3D Metal Printing of Stamping Tools & Dies and Injection Molds2019Inngår i: The 11th Tooling Conference and Exhibition 2019: Communication along the supply chain in the tooling industry, 2019Konferansepaper (Fagfellevurdert)
    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.

  • 172.
    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 application2001Inngår i: The Tube & Pipe Journal, Vol. 12, nr 2, s. 13-17Artikkel i tidsskrift (Fagfellevurdert)
  • 173.
    Asnafi, Nader
    et al.
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Andersson, Roger
    Persson, Martin
    Liljengren, Magnus
    Comparison of Lightweight Solutions: Low Cost Production Process for High Strength Boron Steel Components2016Konferansepaper (Annet vitenskapelig)
  • 174.
    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 treatment2016Konferansepaper (Annet vitenskapelig)
    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.

  • 175.
    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 Sheets1998Rapport (Annet vitenskapelig)
  • 176.
    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 Applications1997Rapport (Annet vitenskapelig)
  • 177.
    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 Sweden2008Rapport (Annet vitenskapelig)
  • 178.
    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 DP6002004Inngår i: 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, s. 193-214Konferansepaper (Fagfellevurdert)
    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.

  • 179.
    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 cars2004Inngår i: 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, s. 263-274Konferansepaper (Fagfellevurdert)
    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.

  • 180.
    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 industries2000Inngår i: Thin-walled structures, ISSN 0263-8231, E-ISSN 1879-3223, Vol. 36, nr 4, s. 289-310Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 181.
    Asnafi, Nader
    et al.
    Swedish Institute for Metals Research, Stockholm, Sweden .
    Larsson, Mats
    On Characterization of Cold Forging Properties of Steels: a New Testing Method1994Rapport (Annet vitenskapelig)
  • 182.
    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 hydropiercing2003Inngår i: SAE technical paper series, ISSN 0148-7191, artikkel-id 2884Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 183.
    Asnafi, Nader
    et al.
    Luleå University of Technology, Luleå, Sweden .
    Magnusson, Claes
    Aluminiumplåt: möjligheter att påverka formningsegenskaperna1988Inngår i: Verkstadstidningen, ISSN 0346-6434, nr 9Artikkel i tidsskrift (Fagfellevurdert)
  • 184.
    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 profiles2000Inngår i: SAE technical paper series, ISSN 0148-7191, artikkel-id 2670Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 185.
    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 profiles2003Inngår i: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774, Vol. 142, nr 1, s. 93-101Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 186.
    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 Cars2002Inngår i: Information Technology, Global Environment and Sheet Metal Forming: Proceedings of the 22nd Biennial Congress, 2002, s. 289-298Konferansepaper (Annet vitenskapelig)
  • 187.
    Asnafi, Nader
    et al.
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Rajalampi, Jukka
    RISE IVF, Olofström, Sweden.
    Aspenberg, David
    DYNAmore Nordic, Linköping, Sweden .
    Design and Validation of 3D-Printed Tools for Stamping of DP6002019Inngår i: IOP Conference Series: Materials Science and Engineering, Institute of Physics Publishing (IOPP), 2019, Vol. 651, artikkel-id 012010Konferansepaper (Fagfellevurdert)
    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.

  • 188.
    Asnafi, Nader
    et al.
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Rajalampi, Jukka
    Aspenberg, David
    DYNAmore Nordic AB, Linköping, Sweden.
    Alveflo, Anton
    Automotive Stamping Tools & Dies and Injection Mold made by Additive Manufacturing through Laser-based Powder Bed Fusion2019Inngår i: Metal Additive Manufacturing Conference: Industrial Perspectives in Additive Technologies, 2019Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Design and production of tools, dies and moulds 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. This paper deals with design and production of stamping tools & dies for sheet metal components and injection moulds for plastic components. Laser-based Powder Bed Fusion (LPBF) is the additive manufacturing (henceforth even called 3D printing) method used in this investigation.

    The stamping tools & dies should withstand the requirements set in stamping of hot-dip galvanized DP600. Solid and topology optimized forming and cutting/blanking/trimming tools made in maraging steel (DIN 1.2709) by LPBF are approved/certified for stamping of 2 mm thick DP600. A working station in a progressive die used for stamping of 1 mm thick DP600 is 3D-printed in DIN 1.2709, both with a honeycomb inner structure and after topology optimization, with successful results. 3D printing results in a significant lead time reduction and improved tool material efficiency. The cost for 3D-printed stamping tools and dies is somewhat higher than the cost of those made conventionally. DIN 1.2709 is certified in this study as tool material for stamping of hot-dip galvanized DP600.

    The core (inserts) of an injection mould 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. Additive manufacturing results in localized tool production and lower total costs. The cooling and cycle time can be improved significantly, if the injection moulding core (inserts) is optimized and 3D-printed in Uddeholm AM Corrax. The best results are obtained, if the 3D-printed core is NOT only an optimized copy of the conventionally designed and manufactured version. The best results are obtained, if the core is redesigned to utilize the full potential of 3D printing.

    This paper accounts for the results obtained in the above-mentioned investigations.

  • 189.
    Asnafi, Nader
    et al.
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Shams, Tawfiq
    Örebro universitet, Handelshögskolan vid Örebro Universitet.
    Aspenberg, David
    DYNAmore Nordic AB, Linköping, Sweden.
    Öberg, Christina
    Örebro universitet, Handelshögskolan vid Örebro Universitet.
    3D Metal Printing from an Industrial Perspective: Product Design, Production and Business Models2018Inngår i: Metal Additive Manufacturing Conference 2018 Proceedings: Industrial perspectives in Additive Technologies, Vienna, Austria: ASMET , 2018, s. 304-313Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper is focused on automotive stamping tools and dies and the impact of 3D metal printing and metals related 3D printing on design and production of such tools and dies. The purpose has been to find out the current industrial potential of 3D printing, as far lead time, costs, shapes, material usage, metal piece size, surface roughness, hardness, strength, and machinability are concerned. The business transformational impact of 3D printing is also addressed in this paper. The obtained results show that the lead time can be halved, the costs are somewhat higher, and the strength, hardness, surface roughness and machinability of the 3D printed metallic tools and dies are as good as those of the conventionally made. The maximum size of a metal piece that can be 3D printed today by Powder Bed Fusion (PBF) is in the best case 500 mm x 500 mm x 500 mm. 3D printing can also be used to make the pattern used to make the mold box in iron and steel casting. It is also possible to eliminate the casting pattern, since the mold box can be 3D printed directly. All this has started to have a large business impact and it is therefore of great significance to outline and execute an action plan almost immediately.

  • 190.
    Asnafi, Nader
    et al.
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Shams, Tawfiq
    Örebro universitet, Handelshögskolan vid Örebro Universitet.
    Aspenberg, David
    DYNAmore Nordic AB, Linköping, Sweden.
    Öberg, Christina
    Örebro universitet, Handelshögskolan vid Örebro Universitet.
    3D Metal Printing from an Industrial Perspective: Product Design, Production, and Business Models2019Inngår i: Berg- und Huttenmännische Monatshefte (BHM), ISSN 0005-8912, E-ISSN 1613-7531, Vol. 164, nr 3, s. 91-100Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper is focused on automotive stamping tools and dies as well as the impact of 3D metal printing and metals related 3D-printing on design and production of such tools and dies. The purpose has been to find out the current industrial potential of 3D-printing as far as lead time, costs, shapes, material usage, metal piece size, surface roughness, hardness, strength, and machinability are concerned. The business transformational impact of 3D-printing is also addressed in this paper. The obtained results show that the lead time can be halved, the costs are somewhat higher, and the strength, hardness, surface roughness, and machinability of the 3D-printed metallic tools and dies are as good as those of the conventionally made. The maximum size of a metal piece that can be 3D-printed today by Powder Bed Fusion (PBF) is, in the best case, 500 mm × 500 mm × 500 mm. 3D-printing can also be used for the pattern to make the mold box in iron and steel casting. It is also possible to eliminate the casting pattern, since the mold box can be 3D-printed directly. All this has started to have a large business impact, and it is therefore of great significance to outline and execute an action plan almost immediately.

  • 191.
    Asnafi, Nader
    et al.
    Volvo Car Components Corp./I., Olofström, Sweden.
    Skogsgårdh, A.
    Volvo Car Components Corp./I., Olofström, Sweden.
    Theoretical and experimental analysis of stroke-controlled tube hydroforming2000Inngår i: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 279, nr 1-2, s. 95-110Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To select tube hydroforming instead of conventional fabrication, one has to know the tube material behaviour and tribological effects during hydroforming and how the hydroforming operation itself should be controlled. The hydroforming operation is either force- or stroke-controlled. This paper deals with stroke-controlled hydroforming. Hydroforming consists of free forming and calibration. In this paper, only the so-called free forming is treated. Stroke-controlled free forming is studied theoretically and experimentally. The theoretical part consists of analytical modeling and finite-element simulations. The conducted experiments are used to show the types of errors that might occur, when the theoretically obtained loading paths are transferred to the hydroforming equipment. The forming limit curve (FLC) is normally used as an aid/instrument in component and process design (which include finite-element simulations). The present study shows that the FLC of the tube material must be determined by hydroforming, if component and process design are to rely on this instrument.

  • 192.
    Asnafi, Nader
    et al.
    Sapa Technology, Finspång (and Vetlanda), Sweden .
    Skogsgårdh, Anders
    Skåre, Thomas
    Hydroforming av rörformiga komponenter: teori och praktik2000Konferansepaper (Annet vitenskapelig)
  • 193.
    Asnafi, Nader
    et al.
    Industrial Development Center/Volvo Cars Body Components, Olofström, Sweden .
    Skogsgårdh, Anders
    Östergren, Nicklas
    Sjöstedt, Jörgen
    HYFO98: Slutrapport1998Rapport (Annet vitenskapelig)
  • 194.
    Asnafi, Nader
    et al.
    Sapa Technology, Finspång (and Vetlanda), Sweden .
    Widlund, Conny
    Håltagning vid hydroformning: material- och processparametrars inverkan på hålkvaliteten2000Rapport (Annet vitenskapelig)
  • 195.
    Aspenberg, David
    et al.
    DYNAmore Nordic AB, Linköping, Sweden.
    Asnafi, Nader
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Topology optimization of a U-bend tool using LS-TaSC2019Inngår i: Proc. of the 12th European LS-DYNA Conference 2019, 2019Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Metal additive manufacturing of stamping tool and die has a potential of reducing the lead time of forming processes, while at least not increasing the cost. As a part of a research project exploring the possibilities to use this type of tool manufacturing techniques, topology optimization using LS-TaSC has been utilized and one example case is presented in this paper, namely a U‑bend tool. This paper looks at the possible benefits from using nonlinear simulations in topology optimization, the effect of chosen target mass fraction value, the interpretations needed of optimal results and the effects on the formed specimen after using an optimized tool. Results show that accounting for the time dependent pressure on the tool, rather than applying a form of equivalent static load, gives a different optimal topology. Some manual interpretations of the optimal results are also recommended, as well as studying the effects on the specimen from removing material on the tool side.

  • 196.
    Atterling, Lise-Lotte
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    TAK-mätning slipmaskiner2014Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Idag är Suzuki Garphyttan AB (SG) en del av Suzuki Metal Industry Group vilket är ett Japanskt företag. SG är världsledande inom tillverkningen av avancerad fjädertråd som används till olika fordonsapplikationer. Kärnverksamheten hos SG är tillverkning och försäljning av ventilfjädertråd, plattråd och profiltråd, oljehärdad tråd, rostfri fjädertråd samt fjädrar. SG har tillverkning av bland annat ventilfjädrar till lastbilar i Fjäderfabriken som är beläget inom fabriksområdet i Garphyttan. Fjäderfabriken genomför ett förbättringsarbete med avsikt att lägga om sin funktionella produktion till linjeproduktion. Kunderna kräver kvalitetscertifieringar och en del kunder har självaavvecklat sin kvalitetskontroll på till exempel fjädrar. Hela kvalitetskontrollen och kvalitetsgarantin ligger då som ansvar hos fjädertillverkningen. Det medför ännu högre krav på kvalitet och driftssäkerhet hos leverantörerna. Utifrån mätning av utnyttjandegraden i form TAK-mätning på slipmaskiner fås data och information om orsakerna till bland annat maskinstillestånd. Det ger underlag till det fortsatta förbättringsarbetet med slipmaskinerna. Projektet som genomförts var TAK-mätning av slipmaskiner och det arbetet har fungerat väl. De resultat som kommit fram har lett till att det som tidigare varit indikationer på låg utnyttjandegrad har mätts och dokumenterats. I det fortsatta arbetet rekommenderas bland annat förebyggande underhåll och beställningsorder på slipade fjädrar till operatörerna för att få en jämnare produktion. Ordern skall vara inom rimlig produktionskapacitet och med största fokus på kvalitet.

  • 197. Bacciu, D.
    et al.
    Broxvall, Mathias
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Coleman, S.
    Dragone, M.
    Gallicchio, C.
    Gennaro, C.
    Guzmán, R.
    Lopez, R.
    Lozano-Peiteado, H.
    Ray, A.
    Renteria, A.
    Saffiotti, Alessandro
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Vairo, C.
    Self-sustaining learning for robotic ecologies2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The most common use of wireless sensor networks (WSNs) is to collect environmental data from a specificarea, and to channel it to a central processing node for on-line or off-line analysis. The WSN technology,however, can be used for much more ambitious goals. We claim that merging the concepts and technology ofWSN with the concepts and technology of distributed robotics and multi-agent systems can open new waysto design systems able to provide intelligent services in our homes and working places. We also claim thatendowing these systems with learning capabilities can greatly increase their viability and acceptability, bysimplifying design, customization and adaptation to changing user needs. To support these claims, we illus-trate our architecture for an adaptive robotic ecology, named RUBICON, consisting of a network of sensors,effectors and mobile robots.

  • 198.
    Bacciu, Davide
    et al.
    Dipartimento di Informatica, Università di Pisa, Pisa, Italy.
    Gallicchio, Claudio
    Dipartimento di Informatica, Università di Pisa, Pisa, Italy.
    Micheli, Alessio
    Dipartimento di Informatica, Università di Pisa, Pisa, Italy.
    Di Rocco, Maurizio
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Saffiotti, Alessandro
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Learning context-aware mobile robot navigation in home environments2014Inngår i: IISA 2014: The 5th International Conference on Information, Intelligence, Systems and Applications, New York: Institute of Electrical and Electronics Engineers (IEEE), 2014, s. 57-62, artikkel-id 6878733Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We present an approach to make planning adaptive in order to enable context-aware mobile robot navigation. We integrate a model-based planner with a distributed learning system based on reservoir computing, to yield personalized planning and resource allocations that account for user preferences and environmental changes. We demonstrate our approach in a real robot ecology, and show that the learning system can effectively exploit historical data about navigation performance to modify the models in the planner, without any prior information oncerning the phenomenon being modeled. The plans produced by the adapted CL fail more rarely than the ones generated by a non-adaptive planner. The distributed learning system handles the new learning task autonomously, and is able to automatically identify the sensorial information most relevant for the task, thus reducing the communication and computational overhead of the predictive task.

  • 199.
    Bakhshi, Betty
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Kartläggning av förbättringsmöjligheter i orderplockningsprocessen2018Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Denna rapport syftar till att analysera orderplockningsprocessen på företaget Reklamlogistik och kartlägga förbättringsmöjligheterna. Reklamlogistik är ett företag inom tredjepartslogistik som har hand om hela logistikkedjan åt sina kunder.

    Det utförda arbetet omfattar både en litteraturstudie för att få en teoretisk infallsvinkel och en nulägesanalys i syfte att kartlägga orderplockningsprocessen.

    Rapporten ska besvara två frågeställningar:

    • • Vilka faktorer påverkar orderplockningsprocessen?
    • • Vilka åtgärder kan tas för att effektivisera orderplockningsprocessen?

    Fyra förbättringsförslag har tagits fram och rekommendationer för det fortsatta arbetet har bifogats.

  • 200.
    Banaee, Hadi
    et al.
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Ahmed, Mobyen Uddin
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Loutfi, Amy
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Towards NLG for Physiological Data Monitoring with Body Area Networks2013Inngår i: 14th European Workshop on Natural Language Generation, 2013, s. 193-197Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This position paper presents an on-goingwork on a natural language generationframework that is particularly tailored fornatural language generation from bodyarea networks. We present an overview ofthe main challenges when considering thistype of sensor devices used for at homemonitoring of health parameters. The paperpresents the first steps towards the implementationof a system which collectsinformation from heart rate and respirationusing a wearable sensor.

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