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  • 1.
    Berntsson, Tomas
    et al.
    Örebro University, Department of Technology.
    Jarl, Magnus
    Örebro University, Department of Technology.
    Alternativ till bly vid värmebehandling av tråd: sammanfattning2003Report (Other academic)
  • 2.
    Berntsson, Tomas
    et al.
    Örebro University, Department of Technology.
    Jarl, Magnus
    Örebro University, Department of Technology.
    Material properties of induction tempered high tensile valve spring wire2006In: Steel Research International, ISSN 1611-3683, Vol. 77, no 11, p. 836-843Article in journal (Refereed)
    Abstract [en]

    Most of today's hardened valve spring wires are tempered in a lead bath. The lead bath provides a stable and accurate degree of tempering of the wire, but it has environmental disadvantages and limitations in flexibility. This paper describes how induction heating can replace lead bath and how this may affect the material properties. The study includes FEM-simulations, calculation of the tempering parameter and experiments with induction tempering of three different SiCr valve spring steels carried out under pilot production. The mechanical properties of the test samples were measured. Fatigue testing of one of the steels was performed on finished springs. The results were evaluated by comparing induction-tempered wire with the conventional lead tempered reference wire. The induction tempered wire fulfilled the product requirements and corresponded in performance with the lead tempered wire.

  • 3.
    Berntsson, Tomas
    et al.
    Örebro University, Department of Technology.
    Sapcanin, Edin
    Örebro University, Department of Technology.
    Hede, Allan
    Örebro University, Department of Technology.
    Jarl, Magnus
    Örebro University, Department of Technology.
    Alternatives to lead bath for heat treatment of wire2003Conference paper (Other academic)
  • 4.
    Berntsson, Tomas
    et al.
    Örebro University, Department of Technology.
    Sapcanin, Edin
    Örebro University, Department of Technology.
    Jarl, Magnus
    Örebro University, Department of Technology.
    Blyfri värmebehandling av tråd2002In: Stål 2002, 2002, p. 50-51Conference paper (Other academic)
  • 5.
    Berntsson, Tomas
    et al.
    Örebro University, Department of Technology.
    Sapcanin, Edin
    Örebro University, Department of Technology.
    Jarl, Magnus
    Örebro University, Department of Technology.
    Segerberg, Sören
    Alternatives to lead bath for patenting of high carbon steel wire2003Conference paper (Refereed)
  • 6.
    Berntsson, Tomas
    et al.
    Örebro University, Department of Technology.
    Sapcanin, Edin
    Örebro University, Department of Technology.
    Jarl, Magnus
    Örebro University, Department of Technology.
    Segerberg, Sören
    Alternatives to lead bath for patenting of high carbon steel wire2004In: Wire Journal International, ISSN 0277-4275, Vol. 37, no 5, p. 82-86Article in journal (Refereed)
    Abstract [en]

    The alternatives to lead bath for patenting of high carbon steel wire are discussed. It is found that it is possible to achieve properties of high-speed gas patented music wire without using a soaking furnace. Laboratory experiments with patenting in a fluidized bed, showed that the process could give the required mechanical properties for the valve spring wire. It is also found that small alterations in process parameters in the industrial trials has a large impact on the mechanical properties and microstructures.

  • 7.
    Gillström, Peter
    et al.
    Örebro University, Department of Technology.
    Jarl, Magnus
    Örebro University, Department of Technology.
    Determination of scale amount on wire of carbon steels and low alloyed steels2002Conference paper (Refereed)
  • 8.
    Gillström, Peter
    et al.
    Örebro University, Department of Technology.
    Jarl, Magnus
    Determination of scale amount on wire of carbon steels and low alloyed steels2003In: Wire Journal International, ISSN 0277-4275, Vol. 36, no 9, p. 73-77Article in journal (Refereed)
    Abstract [en]

    Scale amount on wire of carbon steels and low alloyed steels was discussed. Metal microscopy and scanning electron microscopy were used. It was found that this method can determine the scale determinations after the material has been stretched.

  • 9.
    Gillström, Peter
    et al.
    Örebro University, Department of Technology.
    Jarl, Magnus
    Örebro University, Department of Technology.
    Mechanical descaling of wire rod using reverse bending and brushing2006In: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774, Vol. 172, no 3, p. 332-340Article in journal (Refereed)
    Abstract [en]

    Wire rods are covered with an oxide layer, which must be removed before wire drawing. This paper presents an investigation of mechanical descaling by reverse bending and brushing as replacement for pickling. Steel grades studied were low carbon steel and silicon chromium steel. Brushing was done with steel brushes and nylon brushes with SiC. The amount of scale remaining after reverse bending of the low carbon steel depended on the roller diameter. After brushing traces of scale remained in valleys on the surface. Surface damage was observed after brushing with steel brushes but not after SiC-nylon brushing. Silicon chromium alloyed steel was not possible to clean by bending and brushing with the roller diameters studied. The electrical energy required for the mechanical descaling of low C steel may be estimated to be 7kWh/tonne with SiC-nylon brushes and 14kWh/tonne with steel brushes. [All rights reserved Elsevier]

  • 10.
    Gillström, Peter
    et al.
    Örebro University, Department of Technology.
    Jarl, Magnus
    Örebro University, Department of Technology.
    Replacement of pickling with shot blasting for wire rod preparation2004In: Scandinavian journal of metallurgy, ISSN 0371-0459, E-ISSN 1600-0692, Vol. 33, no 5, p. 269-278Article in journal (Refereed)
    Abstract [en]

    An oxide scale layer covers steel wire rod produced by hot rolling. This oxide is often removed by pickling before wire drawing; otherwise, hard oxides will be impressed into the wire surface and give an inferior surface quality. Stricter pollution regulations increase the incentive to replace pickling with mechanical descaling. This paper gives results from tests on carbon steels by using shot blasting to descale wire rod. The tests include: (i) shot blasting experiments in an industrial full-scale in-line shot blasting machine, (ii) laboratory drawing experiments on shot blasted wire rod, (iii) industrial trials on shot blasted wire rod at the drawing plants. There are differences in the appearance of surfaces between shot blasted and pickled wires, but no differences in the drawing process were observed in the laboratory experiment. In the industrial trials the wear of dies were more severe when drawing shot blasted wire of one of the steel grades. In the downstream processes, problems were recorded with the cleanness of the surface of another grade and adhesion of copper coating on a third grade.

  • 11.
    Gillström, Peter
    et al.
    Örebro University, Department of Technology.
    Jarl, Magnus
    Örebro University, Department of Technology.
    Valstrådspreparering - alternativ till betning vid tråddragning: slutrapport2003Report (Other academic)
  • 12.
    Gillström, Peter
    et al.
    Örebro University, Department of Technology.
    Jarl, Magnus
    Örebro University, Department of Technology.
    Wear of die after drawing of pickled or reverse bent wire rod2007In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 262, no 7-8, p. 858-867Article in journal (Refereed)
    Abstract [en]

    The object of this paper was to evaluate the difference of die wear by using wire rods descaled by two different treatments; pickling or reversed bending. The paper gives a background of wear mechanism and describe a method to estimate die wear in wire drawing. The conclusions of the experiments were that the wire rod preparation seems to be of minor importance for the wear of die. A die in the sixth draft had a magnitude lower wear, compared to the die in the first draft. Abrasive wear is present from the WC grains, torn out in the adhesive wear, on both dies used on pickled wire rod and reverse bent and steel wool cleaned wire rod. © 2006 Elsevier B.V. All rights reserved.

  • 13.
    Jarl, Magnus
    Örebro University, Department of Technology.
    Automatisering, mätning och styrning av kvalitetspåverkande faktorer vid tråddragning2009Conference paper (Other academic)
  • 14.
    Jarl, Magnus
    Örebro University, Department of Technology.
    Automatisering, mätning och styrning av kvalitetspåverkande faktorer vid tråddragning: analys av smörjningsprocessen – litteraturgenomgång2007Report (Other academic)
  • 15.
    Jarl, Magnus
    Örebro University, School of Science and Technology.
    Automatisering, mätning och styrning av kvalitetspåverkande parametrar vid tråddragning2012Report (Other academic)
    Abstract [en]

    A number of methods, which possibly may be used for monitoring of the wire-drawing process, have been surveyed and some have been studied. The possibility to monitor wear of dies by calculations of the PLC-system has been studied. Optical methods and force signals for detection of flaws has been studied.

     

    Trials to monitor the wear of drawing dies showed that the PLC-system was not accurate enough. The reason is most likely because of inaccurate wire speed measurement. Optical inspection of the wire in-line was complicated by lubricant flakes remaining on the wire surface and not possible to separate from defects. Additionally, the optical equipment was extremely expensive.

    A number of industrial with studies of force signals has been done. The correlation between and scratches on the wire surface is not straight-forward. Sever scratching may be detected by force signals, but a single scratch is hard to find. The brightness of the wire may be monitored by a pyrometer or with a digital or web camera. This method gives only an indication of the condition of the lubrication.

  • 16.
    Jarl, Magnus
    Örebro University, Department of Technology.
    Egenskaper hos oxider på kolstål: litteraturstudie2003Report (Other academic)
  • 17.
    Jarl, Magnus
    Örebro University, Department of Technology.
    Forskning inom formningsteknik vid Örebro universitet2002In: Nordisk trådteknisk förenings årsmöteskonferens, 2002, p. 63-69Conference paper (Other academic)
  • 18.
    Jarl, Magnus
    Örebro University, Department of Technology.
    Vad är oxid på kolstål2003Report (Other academic)
  • 19.
    Jarl, Magnus
    Örebro University, Department of Technology.
    Värmebehandling av tråd utan bly2006Conference paper (Other academic)
  • 20.
    Jarl, Magnus
    et al.
    Örebro University, Department of Technology.
    Axelsson, Fredrik
    Wear of dies, measured and calculated by the process control system in a drawing machine2008Conference paper (Other academic)
    Abstract [en]

    This paper discusses an industrial trial in a drawing machine. The final dimensions have been measured and calculated from wire weight and length, yielding calculations of dimensions within ±0.01 mm. The dimension measurements in different drafts were compared to the dimensions given by the process control system. It was found that accuracy was not satisfactory, and the wear of the dies was correlated to the wire length.

  • 21.
    Jarl, Magnus
    et al.
    Örebro University, Department of Technology.
    Axelsson, Fredrik
    Wear of dies, measured and calculated by the process control system in a drawing machine2009In: Wire Journal International, ISSN 0277-4275, Vol. 42, no 10, p. 80-83Article in journal (Refereed)
  • 22.
    Jarl, Magnus
    et al.
    Örebro University, Department of Technology.
    Berntsson, Tomas
    Örebro University, Department of Technology.
    Sapcanin, Edin
    Örebro University, Department of Technology.
    Azizi, Basid
    Örebro University, Department of Technology.
    Replacement of lead baths for the tempering of spring wire2003In: Scandinavian journal of metallurgy, ISSN 0371-0459, E-ISSN 1600-0692, Vol. 32, no 5, p. 241-246Article in journal (Refereed)
    Abstract [en]

    Molten lead is used for tempering of valve-spring wire. Lead has drawbacks due to slow temperature changes. In 1991 the Swedish Parliament passed a Government Bill, in which proposals were made to phase out the use of lead in the long term, primarily through voluntary measures. Tempering of SIS 2090 (SAE 9254, DIN 55SiCr7) wire with different dimensions using induction heating was tested in a pilot process line. An induction coil for six wires and two coils with different lengths designed for single wires were tested. The results showed that an induction coil for six wires gave excessive temperature and property variations between the wires. The shorter of the single wire coils gave fluctuations in temperature and properties using a 3.00-mm wire. No such fluctuations were observed with the longer coil. One of the experiments showed that the process might need time to reach stable conditions. The results so far indicate that it is possible to produce valve-spring wire with induction tempering. The process needs more control and monitoring compared to tempering in molten lead. © Blackwell Munksgaard, 2003.

  • 23.
    Jarl, Magnus
    et al.
    Örebro University, Department of Technology.
    Gillström, Peter
    Örebro University, Department of Technology.
    Alternativ till betning, valstrådspreparering2002In: 1428 dagar med U2000: en presentation av forsknings- och utvecklingsprojekt inom Universitetsfonden 2000 1 januari 1999 –28 november 2002, 2002, p. 39-41Chapter in book (Other academic)
  • 24.
    Jarl, Magnus
    et al.
    Örebro University, Department of Technology.
    Hede, Allan
    Örebro University, Department of Technology.
    Berntsson, Tomas
    Örebro University, Department of Technology.
    Sapcanin, Edin
    Örebro University, Department of Technology.
    Blyfri värmebehandling av tråd2002In: 1428 dagar med U2000: en presentation av forsknings- och utvecklingsprojekt inom Universitetsfonden 2000 1 januari 1999 –28 november 2002, 2002, p. 48-50Chapter in book (Other academic)
  • 25.
    Jarl, Magnus
    et al.
    Örebro University, Department of Technology.
    Pettersson, Kjell
    Örebro University, Department of Technology.
    FEM vid tråddragning: resultat av dragningsförsök med 316L2001Report (Other academic)
  • 26.
    Jarl, Magnus
    et al.
    Örebro University, Department of Technology.
    Överstam, Henrik
    Örebro University, Department of Technology.
    FEM vid tråddragning: resultat av dragförsök med SKF8032007Report (Other academic)
  • 27.
    Jarl, Magnus
    et al.
    Örebro University, Department of Technology.
    Överstam, Henrik
    Örebro University, Department of Technology.
    Finit Elementmodellering (FEM) vid tråddragning2002In: 1428 dagar med U2000: en presentation av forsknings- och utvecklingsprojekt inom Universitetsfonden 2000 1 januari 1999 –28 november 2002, 2002, p. 51-54Chapter in book (Other academic)
  • 28.
    Jarl, Magnus
    et al.
    Örebro University, Department of Technology.
    Överstam, Henrik
    Örebro University, Department of Technology.
    Simulation of temperatures in the wiredrawing process2008In: Wire Journal International, ISSN 0277-4275, Vol. 41, no 2, p. 150-155Article in journal (Refereed)
  • 29.
    Jarl, Magnus
    et al.
    Örebro University, Department of Technology.
    Överstam, Henrik
    Örebro University, Department of Technology.
    Simulation of temperatures in the wiredrawing process2007Conference paper (Refereed)
    Abstract [en]

    Hydrodynamic theory predicts higher pressure at higher drawing speed, but the opposite is true. The temperature in the area of wire and die interface influences lubricant properties, including viscosity. In this paper, the wiredrawing process was studied by means of coupled thermo-mechanical simulations using the Finite Element Method. The temperatures in the die, the wire, and the interface were evaluated, for different parameters such as wire steel grade, drawing speed, and die cooling conditions. This paper discusses their influence on lubrication.

  • 30.
    Johansson, Helena
    et al.
    Örebro University, School of Science and Technology.
    Jarl, Magnus
    Örebro University, School of Science and Technology.
    Teknik för högre draghastighet2010In: Nordisk trådteknisk förening: årsmötesbok, Hallstahammar: Nordisk trådteknisk förening (NTTF) , 2010, p. 49-55Conference paper (Other academic)
    Abstract [sv]

    Arbetet med projektet Teknik för högre draghastighet har inletts med studier av hur kylsystem för dragskivor är konstruerade, några försök att teoretiskt studera värmetransport i gränsytor och FEM simuleringar av temperaturen i dragskivor.

  • 31.
    Karlsson, Patrik
    et al.
    Örebro University, Department of Technology.
    Jarl, Magnus
    Örebro University, Department of Technology.
    Wire cast obtained by use of roll straightening as an alternative to turning of the die box2005Report (Other academic)
  • 32.
    Karlsson, Patrik
    et al.
    Örebro University, Department of Technology.
    Jarl, Magnus
    Örebro University, Department of Technology.
    Enghag, Per
    Örebro University, Department of Technology.
    Use of roller straightener to produce wire cast2005In: Hutnik, ISSN 0018-8077, Vol. 72, no 2, p. 69-71Article in journal (Refereed)
    Abstract [en]

    A three roller and a two roller straightener were used to produce the wire cast. The three roller straightener was not appropriate, but with the two roller straightener it was possible to produce the required wire cast. Cast was measured before and after the wire entered the capstan. Results of different straightener setting are reported. Micro hardness measurements in the cross sections of the wires revealed no problems with this method.

  • 33.
    Larsson, Joakim
    et al.
    Örebro University, School of Science and Technology.
    Jarl, Magnus
    Örebro University, School of Science and Technology.
    Högre draghastighet2012In: Nordisk trådteknisk förening: Årsmötesbok, Örebro: Nordisk trådteknisk förening (NTTF) , 2012, p. 63-70Conference paper (Other academic)
    Abstract [sv]

    Tråddragningsprocessen har studerats med försök och FEM-simuleringar. Försök har genomförts med ändringar i nibshållare. Försöken visar att draghastigheten kan ökas och skivslitaget minskas.

  • 34.
    Larsson, Joakim
    et al.
    Örebro University, School of Science and Technology.
    Jarl, Magnus
    Örebro University, School of Science and Technology.
    Teknik för högre draghastigheter: tempearturens inverkan2011In: Nordisk trådteknisk förening: årsmötesbok, Hallstahammar: Nordisk trådteknisk förening (NTTF) , 2011, p. 53-60Conference paper (Other academic)
    Abstract [sv]

    Temperaturer i tråddragningsprocessen har studerats vid ett industriförsök i Hjulbro. Temperaturer har mätts på nibs, tråd på block och kylvatten. Simuleringar har utförts med finita element metoden, FEM. Programmet som simuleringarna utförs i är Marc Mentat 2010.

  • 35.
    Larsson, Joakim
    et al.
    Örebro University, School of Science and Technology.
    Johansson-Cider, Helena
    Karlstad Universitet, Karlstad, Sweden.
    Jarl, Magnus
    Örebro University, School of Science and Technology.
    Monitoring of the wiredrawing process2013In: Wire Association International: Annual Convention, 2013Conference paper (Other academic)
    Abstract [en]

    Manual monitoring for flaws, which is dependent on operator experience, is normal praxis during wiredrawing. This paper investigates different methods to monitor the drawing process. Force measurement and an optical method have been tested in plant experiments. Monitoring of the drawing force gives some information, but is not reliable. Optical methods are expensive and sensitive for variation in the lubricant layer.

  • 36.
    Larsson, Joakim
    et al.
    Örebro University, School of Science and Technology.
    Johansson-Cider, Helena
    Karlstad Universitet, Karlstad, Sweden.
    Jarl, Magnus
    Örebro University, School of Science and Technology.
    Temperatures in the Wire Drawing Process: Measurements and Simulations2013In: Wire Association International: Annual Convention, 2013Conference paper (Other academic)
    Abstract [en]

    The effect of high nib temperatures in the wiredrawing process was analyzed via thermocouples, with the results compared to FEM simulations.

  • 37.
    Larsson, Joakim
    et al.
    Örebro University, School of Science and Technology.
    Johansson-Cider, Helena
    Karlstad universitet, Karlstad, Sweden.
    Jarl, Magnus
    Örebro University, School of Science and Technology.
    Temperatures in the wiredrawing process: Measurements and simulations2014In: Wire Journal International, ISSN 0277-4275, Vol. 47, no 2, p. 128-133Article in journal (Refereed)
    Abstract [en]

    The effect of high nib temperatures in the wiredrawing process was analyzed via thermocouples, with results comparded to FEM simulations.

  • 38. Marston, H. F.
    et al.
    Bolt, P. H.
    Leprince, G.
    Röder, M.
    Klima, R.
    Niska, J.
    Jarl, Magnus
    Örebro University, Department of Technology.
    Challenges in the modelling of scale formation and decarburisation of high carbon, special and general steels2004In: Ironmaking & steelmaking, ISSN 0301-9233, E-ISSN 1743-2812, Vol. 31, no 1, p. 57-65Article in journal (Refereed)
    Abstract [en]

    The oxygen bearing gases of the atmosphere in a reheating furnace oxidise the feedstock producing scale on the surface of the metal and, for high carbon steels, cause decarburisation of the surface layers. Modelling of these effects has to take into account the competitive nature of the two processes, scale formation and decarburisation, and complications that arise from changes in the controlling mechanism. Initially, the rate of scale formation may be controlled by effects in the gas phase, or nucleation of scale on the metal surface. Subsequently, scale growth is influenced by the gas composition and may be disturbed by the accumulation of oxidation products at the scale-metal interface. Voids and cracks within the scale may either inhibit solid state diffusion within the scale or provide channels for oxidising gas to access the scale-metal interface, For decarburisation, complications arise if a ferrite rim creates a step in the carbon profile or if retention of carbon monoxide within the scale provides a thermodynamic barrier to the reaction. This paper considers these complications and how they may be handled in mathematical models.

  • 39.
    Marston, H. F.
    et al.
    Corus U.K..
    Leprince, G.
    IRSID France.
    Bolt, P. H.
    Corus.
    Röder, N.
    Klima, R.
    Niska, J.
    Jarl, Magnus
    Örebro University, Department of Technology.
    Challenges in the modelling of scale formation and decarburisation of high carbon, special and general steels2002Conference paper (Refereed)
  • 40.
    Sastry, K. Y.
    et al.
    Det Norske Veritas, Høvik, Norway.
    Nokleby, John Olav
    Det Norske Veritas, Høvik, Norway.
    Hekkanen, Mikko
    Örebro University, School of Science and Technology.
    Jarl, Magnus
    Örebro University, School of Science and Technology.
    Inclusion rating of clean steels: a study on role of steel cleanliness on fatigue performance of forged steel components used in marine propulsion2010Conference paper (Other academic)
    Abstract [en]

    Det Norske Veritas (DNV) Maritime, Section for Machinery, is responsible for approval of machinery in ships for DNV Class. Allowable fatigue stresses in forged steel is a key input parameter for such evaluations, and are regulated in DNV’s Rules. It is well known that the cleanliness of the steel is important for its fatigue strength. To account for this, “clean steel” has been defined in DNV’s Rules for forgings. For “clean steel”, an extra 10% is allowed in the components fatigue strength, compared to ordinary forged steels. Clean steel is given a factor of 1.1. Recently, one leading steel manufacturer has claimed that even higher benefits can be gained by using “super clean steels”, and a factor 1.15 has been claimed. The improvement has been demonstrated by fatigue testing. It appears that although the claimed 125% may be justified, there are limits to how much gain it is possible to obtain by increasing steel cleanliness. In order to approve such increased fatigue strength in attempt has been made to find ways to correlate demonstrated cleanliness to increased fatigue strength by chemical and/or metallographic means without performing extensive fatigue test series. Only with such criteria, it is possible to certify “super clean steel”, and accept the use of its increased fatigue strength with reference to the material certificate. This paper covers a study concerning the methods that are available for determining the cleanliness level for steels. Examples of methods that can be used for finding and testing material for the presence of big inclusions are reported.

  • 41.
    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)
  • 42.
    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)
  • 43.
    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)
  • 44.
    Överstam, Henrik
    et al.
    Örebro University, Department of Technology.
    Jarl, Magnus
    Örebro University, Department of Technology.
    FEM vid tråddragning: slutrapport2003Report (Other academic)
  • 45.
    Överstam, Henrik
    et al.
    Örebro University, Department of Technology.
    Jarl, Magnus
    Örebro University, Department of Technology.
    FEM-simulation of drawing out in open die forging2004In: Steel Research International, ISSN 1611-3683, Vol. 75, no 12, p. 812-817Article in journal (Refereed)
    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.

  • 46.
    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)
  • 47.
    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

  • 48.
    Överstam, Henrik
    et al.
    Örebro University, Department of Technology.
    Lundberg, Sven-Erik
    Örebro University, Department of Technology.
    Jarl, Magnus
    Örebro University, Department of Technology.
    Finite element modelling and laboratory simulation of high speed wire rod rolling in 3-roll stands2003In: Steel Research International, ISSN 1611-3683, Vol. 74, no 7, p. 431-443Article in journal (Refereed)
    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.

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