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  • 2051.
    Öunapuu, Anton
    Örebro University, School of Science and Technology.
    Framställning av en teoretisk bokningsmodell för tids- och kostnadseffektivisering av tomvagnstransporter hos ScandFibre Logistics AB2022Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    ScandFibre Logistics AB (SFL) is a logistics company operating in the railway industry and is a part of BillerudKorsnäs. SFL offers logistic solutions for railway transport of products from BillerudKorsnäs’, as well as a few other external customers’, different paper mills to roughly 50 different terminals in Europe. In conjunction with SFL:s own interest of developing the efficiency of their own operations and handling of wagon transports, this master’s thesis aims to improve knowledge and investigate how to streamline the transport of empty wagons from Swedish terminals back to the paper mills, in regards to transport and rental costs. Information have been gathered through interviews with several employees, through participating observations, and with the extraction of raw data from SFL’s database. With a descriptive method the overall operation at SFL could be outlined, serving as the base for a model development phase. This phase resulted in this thesis’ proposed bookings model for empty wagon transports. The model acquires a theoretical streamline way of booking empty wagon transports in such a manner that wagons arrive at the paper mills according to the JIT-principle. The model succeeds in doing this by generating booking proposals using mathematical logic and time-sensitive booking criteria, with the focus being transports of short distances; in theory also meaning a time efficient use of each wagon. As the model is theoretically constructed and relies on several generalizing assumptions, its booking proposals should always be evaluated from a perspective of practicality by executive booking personnel.  

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  • 2052.
    Överstam, Henrik
    Örebro University, Department of Technology.
    Evaluation of the improvement of rolling analysis by means of modern technology2006Conference paper (Other academic)
    Abstract [en]

    Modern wire rod rolling is characterised by high rolling speed and requirements on well-defined mechanical properties as well as close tolerances. Traditional methods for analyses of this kind of processes, such as the slip line field theory and the upper bound analysis, have proven not to be sufficient. Different methods for rolling analysis have been evaluated. Several FE approaches were compared to classical methods such as the upper bound and the slip line theory and the results was validated by practical experiments. The finite element method has proven to be a powerful tool in order understand the metal working process, it also gives the possibility to study phenomena not yet clarified.

  • 2053.
    Överstam, Henrik
    Örebro University, Department of Technology.
    FEM vid tråddragning2003Report (Other academic)
  • 2054.
    Överstam, Henrik
    Örebro University, Department of Technology.
    FEM vid tråddragning2004In: Stål 2004, 2004, p. 61-62Conference paper (Other academic)
  • 2055.
    Överstam, Henrik
    Örebro University, Department of Technology.
    FEM vid tråddragning2002Conference paper (Other academic)
  • 2056.
    Överstam, Henrik
    Örebro University, Department of Technology.
    FEM vid tråddragning: resultat av dragförsök med 18-8 och GF752003Report (Other academic)
  • 2057.
    Överstam, Henrik
    Örebro University, Department of Technology.
    Finita Element Modellering (FEM) vid tråddragning2002In: Stål 2002, 2002, p. 54-55Conference paper (Other academic)
  • 2058.
    Överstam, Henrik
    Örebro University, Department of Technology.
    The influence of bearing geometry on the residual stress state in cold drawn wire, analysed by the FEM2006In: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774, Vol. 171, no 3, p. 446-450Article in journal (Refereed)
    Abstract [en]

    Finite element simulations have been performed in order to study the influence of bearing geometry on the residual stress-state in cold drawn wires. Experiments in full industrial scale have been performed in order to verify the FEM results. The residual stresses were measured with X-ray diffraction in both the axial and tangential direction. The material used was a high carbon steel for roller bearings, 100Cr6. It was found that the geometry of the bearing has a large influence of the residual stress-state. When the bearing is somewhat tapered, a gap in the beginning of the bearing is formed. This "double contact" reduces the axial and tangential residual stress to minimum or even to a compressive state. A cylindrical bearing gave no contact in the bearing at all due to elastic deformation. This resulted in a large axial and tangential residual stress. It was shown that even a small divergence from the desired bearing geometry due to the grinding of the die could affect the residual stress immensely.

  • 2059.
    Överstam, Henrik
    Örebro University, Department of Technology.
    The interdependence of plastic behaviour and final properties of steel wire, analysed by the finite element method2004Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The finite element method (FEM) has been used in order to study the interdependence of plastic behaviour and final properties in steel wire. Three processes metal forming have been studied: billet forging, wire rod rolling, and cold drawing.

    The forging study focuses on the possibilities to eliminate voids, pores and pipes by altering the bite ratio in open die forging. Forging is used in wire manufacturing when dealing with materials that are difficult or impossible to roll, e.g. tool steels like high-speed steels, and powder metallurgically manufactured materials like tungsten-molybdenum filament wire. The elimination of inner defects by forging were successfully simulated by the FEM.

    The rolling study focuses on the problems due of the extreme finish rolling velocities in modern wire rod mills and modern technologies such as thermo-mechanical rolling and sizing. A design for a high-speed laboratory mill for studies of material behaviour at extreme strain rates was made. With a combination of two-high stands and three-roll units is it possible to obtain a smoother temperature distribution in the bar cross section.

    Two studies of the cold drawing process were made. The first describes the distribution of the plastic deformation due to the die geometry. It was found that the influence of the die angle on the amount of inhomogeneous deformation decreases with increasing area reduction. The frictional behaviour was also studied.

    The second study describes how the bearing geometry affects the residual stress-state in the wire. It was found that a small taper could change the residual stress state in the surface immensely. This was shown with FE simulations and verified by X-ray diffraction measurements. The results in this paper gives a tool for control of the residual stress-state in the wire. This gives a possibility to increase e.g. the fatigue strength in the final product.

    List of papers
    1. FEM-simulation of drawing out in open die forging
    Open this publication in new window or tab >>FEM-simulation of drawing out in open die forging
    2004 (English)In: Steel Research International, ISSN 1611-3683, Vol. 75, no 12, p. 812-817Article in journal (Refereed) Published
    Abstract [en]

    Experiments and finite element simulations were performed in order to study how the bite ratio influences the closing of inner flaws such as voids and pipes in the open die forging process. Square rolled blooms of carbon steel with a transversal hole in the centre were forged with a constant height reduction but with different bites in order to study the closing of voids during the process. Corresponding finite element simulations were performed in full 3D with full thermo-mechanical coupling. Also the influence of the friction and of the temperature gradient in the workpiece were studied. The elimination of an artificial defect by forging was successfully simulated by the finite element method. It is established that the closure of voids is highly dependent on the bite ratio. The closure of voids under the edge of the tool is however not improved by a higher bite ratio. There is a slight tendency that the situation under the tool edge is worse when the bite ratio is increased.

    Place, publisher, year, edition, pages
    Düsseldorf: Verlag Stahleisen, 2004
    Research subject
    maskinteknik
    Identifiers
    urn:nbn:se:oru:diva-3208 (URN)
    Available from: 2004-11-18 Created: 2004-11-18 Last updated: 2017-10-18Bibliographically approved
    2. Finite element modelling and laboratory simulation of high speed wire rod rolling in 3-roll stands
    Open this publication in new window or tab >>Finite element modelling and laboratory simulation of high speed wire rod rolling in 3-roll stands
    2003 (English)In: Steel Research International, ISSN 1611-3683, Vol. 74, no 7, p. 431-443Article in journal (Refereed) Published
    Abstract [en]

    Modern wire rod rolling is characterized by high finish rolling speed and requirements on close tolerances and well defined mechanical properties of the rolled product. In some senses the technological development has run in advance of the scientific knowledge of the phenomena involved in the process. Thus at present no laboratory mill is in operation for rolling speeds above 40 m/s. The modern technologies on thermomechanical rolling and sizing give certain phenomena difficult to handle for the mills, and especially finish rolling at low reductions and temperatures performed in three-roll units sometimes give surprises on grain size distribution and allied properties of the wire rod. Traditional plastic analysis has proven not to be sufficient to analyse the processes involved in high speed rolling of close tolerance wire rod with well-defined properties. Simulations by means of the Finite Element Method on the other hand have proven to be a powerful tool for this kind of analysis, even if the initial difficulties in creating a suitable model require certain care. Also the calculation capacity must be sufficient for making relevant three-dimensional thermomechanically coupled studies. The high speed rolling of wire rod can be simulated under full-scale conditions, and with correct boundary condition in the high-speed laboratory wire rod mill at Orebro University. By utilizing both conventional two-high stands and three-roll units it has been possible to design a laboratory rolling mill for any rolling condition that can occur in wire rod mills. Rolling speeds up to 80 m/s can be combined with thermo-mechanical rolling in any interesting temperature range, and with total flexibility of reductions. Further, fundamental studies of high-speed deformations can be performed in full-scale and with correct frictional conditions and geometries. Thanks to the flexibility in layout and combinations with other equipment in the laboratory also other processes can be simulated.

    Place, publisher, year, edition, pages
    Düsseldorf: Verlag Stahleisen, 2003
    Research subject
    Mechanical Engineering
    Identifiers
    urn:nbn:se:oru:diva-4062 (URN)
    Available from: 2007-06-21 Created: 2007-06-21 Last updated: 2017-10-18Bibliographically approved
    3. Development and validation of FEM models for wiredrawing
    Open this publication in new window or tab >>Development and validation of FEM models for wiredrawing
    2004 (English)In: Wire Journal International, ISSN 0277-4275, Vol. 37, no 5, p. 73-76Article in journal (Refereed) Published
    National Category
    Engineering and Technology
    Research subject
    Mechanical Engineering
    Identifiers
    urn:nbn:se:oru:diva-3210 (URN)
    Available from: 2004-11-18 Created: 2004-11-18 Last updated: 2017-10-18Bibliographically approved
    4. The influence of bearing geometry on the residual stress state in cold drawn wire, analyzed by the FEM
    Open this publication in new window or tab >>The influence of bearing geometry on the residual stress state in cold drawn wire, analyzed by the FEM
    (English)Manuscript (preprint) (Other academic)
    Research subject
    Mechanical Engineering
    Identifiers
    urn:nbn:se:oru:diva-3211 (URN)
    Available from: 2004-11-18 Created: 2004-11-18 Last updated: 2017-10-18Bibliographically approved
  • 2060.
    Överstam, Henrik
    et al.
    Örebro University, Department of Technology.
    Eriksson, Conny
    Fagersta Stainless.
    Lundberg, Sven-Erik
    Örebro University, Department of Technology.
    The importance of proper roll pass design and entry guiding on the improvement of the surface quality in wire rod rolling2006In: Der Kalibreur, ISSN 0022-796X, Vol. 67, p. 51-65Article in journal (Refereed)
  • 2061.
    Överstam, Henrik
    et al.
    Örebro University, Department of Technology.
    Eriksson, Conny
    Lundberg, Sven-Erik
    Örebro University, Department of Technology.
    The importance of proper roll pass design and entry guiding on the improvement of the surface quality in wire rod rolling2005Conference paper (Other academic)
  • 2062.
    Överstam, Henrik
    et al.
    Örebro University, Department of Technology.
    Jarl, Magnus
    Örebro University, Department of Technology.
    Development and validation of FEM models for wire drawing2003In: Interwire 2003, 2003, p. 138-147Conference paper (Refereed)
  • 2063.
    Överstam, Henrik
    et al.
    Örebro University, Department of Technology.
    Jarl, Magnus
    Örebro University, Department of Technology.
    Development and validation of FEM models for wiredrawing2004In: Wire Journal International, ISSN 0277-4275, Vol. 37, no 5, p. 73-76Article in journal (Refereed)
  • 2064.
    Överstam, Henrik
    et al.
    Örebro University, Department of Technology.
    Jarl, Magnus
    Örebro University, Department of Technology.
    FEM vid tråddragning: simulering i 2D av SKF 8032002Report (Other academic)
  • 2065.
    Överstam, Henrik
    et al.
    Örebro University, Department of Technology.
    Jarl, Magnus
    Örebro University, Department of Technology.
    FEM vid tråddragning: slutrapport2003Report (Other academic)
  • 2066.
    Överstam, Henrik
    et al.
    Örebro University, Department of Technology.
    Jarl, Magnus
    Örebro University, Department of Technology.
    Finite element method at wire drawing2003Conference paper (Other academic)
  • 2067.
    Överstam, Henrik
    et al.
    Örebro University, School of Science and Technology.
    Johansson, Helena
    Örebro University, School of Science and Technology.
    Jarl, Magnus
    Örebro University, School of Science and Technology.
    Temperatures at wire-drawing: simulations and verification efforts2011In: Hutnik: vol 78, 2011, p. 98-100Conference paper (Other academic)
    Abstract [en]

    Temperatures are very important in the wire drawing process. They are hard to measure direct, but a combination of simulations and measurements can give valuable information

  • 2068.
    Överstam, Henrik
    et al.
    Örebro University, Department of Technology.
    Lundberg, Sven-Erik
    Örebro University, Department of Technology.
    A new approach to roll force and torque modelling in wire rod and bar mills2008In: Der Kalibreur, ISSN 0022-796X, Vol. 69, p. 61-72Article in journal (Refereed)
  • 2069.
    Överstam, Henrik
    et al.
    Örebro University, Department of Technology.
    Lundberg, Sven-Erik
    Örebro University, Department of Technology.
    A new approach to roll force and torque modelling in wire rod and bar mills2007Conference paper (Other academic)
  • 2070.
    Özkanat, Fatih
    et al.
    Örebro University, School of Science and Technology.
    Yañez Hernandez, Kevin
    Örebro University, School of Science and Technology.
    Grus till väggelementPrefabricering2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Prefabrication of wall elements and other finished construction elements has been standardized recently in the construction industry. What is usually not in the mind of the construction industry is how the environment is affected as the main priority lies in the economy. The work involved a lot about half prefabrication and full prefabrication for an inner wall and how much energy is consumed as well as carbon dioxide emissions. This was done using an LCA as a way to study the sustainability of the products. The inner walls were a sandwich wall (fully prefabricated) and shell wall (semi prefabricated).First, data was collected from the material usage of the company. The density and material mass were developed and carried out using scientific articles / databases and companies. After that CO2 emissions and energy use were calculated using collected data for both inner walls. At last NTM Calc calculated transport distance between the operations and this led to the result.Using a Life Cycle Assessment, all carbon dioxide emissions and energy use processes were taken from beginning to end of both inner walls. The result obtained was not as expected, both the Sandwich wall and the Shell wall did not have the same carbon dioxide emissions, but energy consumption was quite similar. What was expected was that carbon dioxide emissions would be quite equal but with smaller margins, but that was not the case.The obtained result was not as expected, both the fully prefabricated sandwich wall and the semi prefabricated shell wall did not have the same carbon dioxide emissions, but energy consumption was quite similar. Theexpectation was that carbon dioxide emissions would be quite equal with smaller margins, but this did not happen.

  • 2071.
    Masterton, Malin (Editor, Creator)
    Örebro University.
    Sjödin, Sofia (Editor, Creator)
    Örebro University.
    ORU2015 Örebro University Research Evaluation 2015: Evaluation Report2015Report (Other academic)
    Abstract [en]

    ORU2015 – Executive Summary

    During 2015, all research performed from 2008 to 2014 at Örebro University, as well as research at Örebro University Hospital, has been evaluated. This report – ORU2015 – presents the background, planning and implementation of the research assessment and its results. Chapter I includes the panel evaluations, and chapter II presents the bibliometric data. Of the 38 subunits of evaluation, 8 are within the Faculty of Business, Science and Engineering, 17 are within the Faculty of Humanities and Social Sciences, 7 within the Faculty of Medicine and Health, and 6 at Region Örebro County’s University Hospital. The evaluation had a meta-analytical approach (see Annex A), and the external multidisciplinary panel assessed the research in each subunit of evaluation (see Annex B). 

    The panel’s evaluation material consisted of a research overview, documentation on academic staff and competence, as well as on funding, self-evaluations and bibliometric data. The self-evaluations by each subunit addressed (i) scientific quality and scientific impact, (ii) impact and outreach, (iii) internationalisation, and (iv) research – education interaction. Each overarching evaluation unit was also assessed, including a SWOT analysis, by the respective heads of schools and deans. Apart from the self-evaluations, the material was retrieved from the university databases, Web of Science and Academic Archive Online (DiVA). The subunits had the opportunity to update their research information for the research overview prior to making the material available to the panel. The fourteen panellists, representing economics, natural sciences and technology, humanities, social sciences, medicine and health sciences, met for two days in October at Örebro University for the evaluation discussions. The agreed evaluation statements were delivered shortly thereafter. 

    The great variability in the subunits’ scientific practices, scale, and establishment had to be accounted for in the panel evaluations. The evaluation subunits range from very large (up to 60 researchers), to medium sized (about 20 researchers), and to quite small subunits (fewer than nine researchers). The points of reference for the panel’s statements were the (i) quality of research, (ii) research environment and infrastructure, (iii) scientific and social interaction and (iv) future potential. Gradings ranged between Excellent (5) and Insufficient (1). The key data in the bibliometric assessment was scientific impact, vitality, productivity and international visibility, as indicated by the publications of each subunit. It can be seen from the panel statement of a subunit and the matching bibliometric data that these two assessments correspond to a large extent, but not completely.

    It is concluded from the panel evaluation that there are Excellent (5), Very Good (4), Good (3), Sufficient (2), as well as Insufficient (1) subunits at the university. A majority of the fourteen subunits that performed well (grade 3 – 5) are medium-sized, whilst the majority of the sixteen weakly performing subunits (grade 1 – 2) are small in size. Of course, for the humanities and social sciences, the Web of Science data only contains output to a limited degree. Therefore data from DiVA has been used and compared as well. For some subunits this makes a difference, but of the 16 subunits that show a weak performance according to Web of Science data, ten also perform weakly as shown in DiVA. Only three of these subunits score Good and one Very Good in DiVA.

    It can be seen from ORU2015 that the research volume, especially expressed in scientific publications per year and citations, has roughly doubled since ÖRE2010. In 2014, the total number of publications in Web of Science by researchers at the university and the university hospital reached some 600 and the number of citations were 14,000 the same year. The ‘findings’ of ORU2015 provide an important basis for decisions by leaders at all levels of the university in terms of strategic planning, support, and development of the research for the future.

    Download full text (pdf)
    ORU2015
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