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  • 251.
    Medvedeva, Anna
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
    Gunnarsson, Staffan
    Research and Development, Uddeholm Tooling AB.
    Andersson, Jörgen
    Research and Development, Uddeholm Tooling AB.
    High-temperature properties and microstructural stability of hot-work tool steels2009In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 523, no 1-2, p. 39-46Article in journal (Other academic)
    Abstract [en]

    Indexable insert tools for machining operations are in service exposed to high temperatures and cyclic mechanical loads. Secondary hardening steels such as hot-work steels are commonly used for tools subjected to thermal exposure. However, these steels, highly alloyed with strong carbide forming elements as Cr, V and Mo, are generally difficult to machine and machining represents a large fraction of the production cost of a tool. Thus, the present study concerns the development of a new steel with improved machinability and meeting the requirements for high-temperature properties.

    Softening resistance of the THG2000 and QRO90 tool steels, commonly used in hot-work applications, and a newly developed tool steel MCG2006 with lower alloying content of carbide forming elements, was investigated by tempering and isothermal fatigue testing. Mechanisms of high-temperature softening of the tested tool steels were discussed with respect to their microstructure and high-temperature mechanical properties. Carbide morphology and precipitation as well as dislocation structure were determined using transmission electron microscopy and X-ray line broadening analysis.

    No difference in softening behaviour was found among the QRO90 and MCG2006 regarding hot hardness measurements. The THG2000 indicated some stabilization of the hardness between 450 and 550 °C and a considerable hardness decrease at higher temperatures.

    The short-time cyclic softening in isothermal fatigue was controlled by dislocation rearrangement and annihilation. The alloying composition of the steels presently tested had no influence on the dislocation density decrease.

    The long-time softening was affected by the material's temper resistance and strongly depended on the carbide morphology and their over-ageing resistance. The QRO90 with greater molybdenum and lower chromium contents than in the THG2000 show the best resistance to softening among the tested grades at all temperatures. The MCG2006, leaner alloyed with the carbide forming elements and alloyed with 4 wt% nickel, has better temper resistance than THG2000 at higher temperatures and longer tempering times.

  • 252.
    Medvedeva, Anna
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Gunnarsson, Staffan
    Research and Development, Uddeholm Tooling AB.
    Andersson, Jörgen
    Research and Development, Uddeholm Tooling AB.
    Krakhmalev, Pavel
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Stress relaxation resistance of tool steels for tool holder applications2009In: Proceedings of the 8th International Tooling Conference, 2-4 June, Aachen, Germany, 2009, 2009, p. 697-712Conference paper (Refereed)
  • 253.
    Medvedeva, Anna
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
    Gunnarsson, Staffan
    Research and Development, Uddeholm Tooling AB.
    Höglund, Dan
    Materials and Process Engineering, AB Sandvik Coromant.
    Stress relaxation resistance for improved fatigue performance of shot peened tool components2008In: Proceedings of the 10th International Conference on Shot Peening, 15-18 September, Tokyo, Japan, 2008 / [ed] Tosha K, Tokyo: Academy Common Meiji University , 2008, p. 286-295Conference paper (Refereed)
    Abstract [en]

    Shot peening is an extensively used process in the production of mechanical components to improve their fatigue strength at ambient temperature. At higher working temperatures of some mechanical components, e.g. from 300 to 600°C, the influence and behaviour of the compressive residual stresses are more uncertain, since they tend to relieve at higher temperatures. The response to shot peening induced residual stresses of low alloyed and hot work tool steels was evaluated with respect to stress relief heat treatments and isothermal high temperature fatigue testing. Not only the residual stresses, but also the material substructure and its dislocation characteristics are of importance. Dislocation structures were determined using X-ray diffraction to explain the preference of the different steel grades. Also, results obtained from bending fatigue testing at ambient temperature of tool components after shot peening and stress relief heat treatments demonstrated the different ability of retaining the fatigue strength.

  • 254.
    Medvedeva, Anna
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Gunnarsson, Staffan
    Research and Development, Uddeholm Tooling AB.
    Krakhmalev, Pavel
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Thermally activated relaxation behaviour of shot peened tool steels for cutting tool body application2011In: materials science and engineering A: Structural Materials: Properties, Microstructures and Processing, ISSN 0921-5093, Vol. 528, no 3, p. 1773-1779Article, review/survey (Other academic)
  • 255.
    Medvedeva, Anna
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Gunnarsson, Staffan
    Research and Development, Uddeholms Tooling AB.
    Krakhmalev, Pavel
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Nordh, Lars Göran
    Research and Development, Uddeholm Tooling AB.
    Influence of nickel content on machinability of a hot-work tool steel in prehardened condition2011In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 32, no 2, p. 706-715Article in journal (Refereed)
    Abstract [en]

    In the present study, the influence of nickel content on the machinability of a prehardened hot-work tool steel was investigated. The machinability with varying nickel content from 1 to 5 wt% was characterized in end milling and drilling by evaluating tool life, cutting forces, and tool/chip interface temperature.

    Nickel content showed to have a positive effect on the machinability of the hot-work tool steel; with increasing nickel content in the steel, the longer tool life was reached in end milling and drilling operations. Machining the higher nickel containing steels generated lower cutting forces and tool/workpiece interface temperature. In addition, less adhesive wear and built-up edge formation were observed on the tools.

    The difference in the steel machinability was discussed in terms of their microstructure and mechanical properties. Increasing nickel content tends to decrease the carbon in the martensite and to retain a fine distribution of small primary carbides. It resulted in a reduction in yield strength with increasing nickel content related to the cutting force reduction and machinability improvement.

  • 256.
    Mesinovic, Orhan
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Vändbord: Lokal Logistik2013Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
  • 257.
    Mikael, Olsson
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013). Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Framtagning och implementering av arbetssätt för utveckling av kostnadseffektiva reservdelar2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Detta examensarbete har utförts som en del av civilingenjörsprogrammet i maskinteknik vid Karlstads Universitet i samarbete med Valmet. För Valmet är försäljning av reservdelar är en vital del av deras totala affär. I avsikt att stärka konkurrenskraften mot kunder i framförallt lågkostnadsländer vill Valmet erbjuda mer kostnadseffektiva lösningar genom att utveckla konstruktionen på befintliga reservdelar. Målet med examensarbetet var därför att ta fram ett systematiskt arbetssätt för produktutveckling av kostnadseffektiva reservdelar och validera det genom implementering på en befintlig produkt i Valmets reservdelssortiment.

     

    Underlaget till det framtagna arbetssättet samlades in genom att utföra en litteraturstudie, en nulägesanalys på Valmet och en intervju på ett företag som är framgångsrikt inom eftermarknad. Arbetssättet syntetiserades som en process med stöttande riktlinjer genom att utgå från Valmets befintliga utvecklingsprocess och integrera teoretiska modeller, principer och verktyg ur vetenskaplig litteratur. Arbetssättet testades sedan på lutmunstycken för sodapannor.

     

    Grunden för det framtagna arbetssättet bestod av en kombination av Value Management och Design to Cost. Fokus i arbetssättet ligger vid att utveckla en reservdel som återställer systemet till sitt normala arbetstillstånd, för ett pris som kunden är beredd att betala, och som balanserar tillförlighet med tillgänglighet så att den totala kostnaden för kunden minimeras.

     

    Genom att implementera det framtagna arbetssättet på lutmunstycken för sodapannor kunde ett förslag på en lösning med 66 % lägre pris och med 50 % lägre total kostnad för kunden tas fram. Implementeringen visade att arbetssättet praktiskt kan användas på enklare reservdelar men att det behöver testas på komplexa produkter av ett tvärfunktionellt team innan det används av Valmet.  Arbetssättet stärker Valmets förutsättningar för att erbjuda ett mer kostnadseffektiv reservdelsortiment.

  • 258. Mitterer, C
    et al.
    Barbist, R.
    Björk, T
    Sundqvist, M
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Hagler, JA
    A comparative study on the evaluation of the tribological behaviour of polymer/zinc coated steel sheets1997Other (Other (popular science, discussion, etc.))
  • 259.
    Montan, Ida
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Analys och utformningsförslag av produktionslina vid ökad ordervolym av katalysatorer: Swenox AB2013Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    The thesis has been performed by Ida Montan, for the mechanical engineering program at Karlstad University. The thesis has been done in cooperation with Swenox AB. It’s a company whose production is located in Nyköping. The company manufactures exhaust systems for heavy and medium heavy trucks and for the bus industry. The thesis is limited to the individual line called the sleevingline which makes catalysts for the exhaust systems. The problem the company has is that the production volume will increase significantly to 2014. A value stream map, VSM, is therefore made on the sleevingline to get an overview over the production and to get a better understanding on how the line works. This is made so that a new value stream map could be made over the 2014 production with the consideration on the higher volume. To cope with the increased production volume, an increase for 85% at the sleevingline, a new layout has been formed over the machinery. Some machines have been added and some has been moved to make the flow of the products as good as possible. The decision of how many machines that should be added vas made from the shift form, how much time that’s available a year. An estimation of how many operators that should be needed a shift was also made. Both the value stream map for 2014 and the new layout over the machinery have been made with thinking of lean production. The lean thinking is used to make the production system as efficient and good as possible. It is doable to within the timeframe up to 2014 to design the production after the results of this thesis. 

  • 260.
    Månsson, Carl
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
    Standardisering och Optimering av fästelement: Volvo bussar Säffle2012Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    This examination project has been carried out at Volvo Buses in Säffle with the main objective to rationalize and standardize the management of none automobile parts, fasteners etc, in the production of  buses.

    The result is a complete list of none automobile parts, where all none automobile parts used in the production of  Volvo buses in Säffle can be found. This list will form the foundation for a list of none automobile parts to be used in other bus factories within the Volvo group. The new list makes it possible to search for a specific none automobile part and find out at which stations it is used, and also get the approximate consumption per standard bus model.

    Overall, this means that the costs, the surcharge per bus, will drop when unnecessary items will be sorted out , and items used infrequently will be handled differently.

    A complete database over all none automobile parts has also been produced, making it possible to search for a none automobile part and find out what it looks like, what category it belongs to, and which company supplies it.

    This project has helped the production teams to develop their routines for continuous control of which none automobile parts are used. The project has also developed routines for checking how a material is placed in the bus structure; if a material is used in few buses per year, the material should be changed in the structure so as not to be a strain on every bus.

     

    During the course of this project, the item numbers of all none automobile parts have been treated, and there is now a standardized way to specify a material using an item number that follows the Volvo group standard.

    The intention was to calculate a new surcharge for the bus. But during the course of the project, problems, lack of time and a lack of commitment from the organization prevented this final part of the analyses from being completed within the project's time frame. Even if the project didn't reach its planned goal, it has still been very useful, and large cost savings can already be identified as a consequence of it.

     The theoretical part of this project aims towards continued use in the production of Volvo Buses. To complete this project, and to be able to make a deeper analysis of parts of the production, an analysis model has been produced that can be elaborated upon.

    Volvo Buses can use the results and information gained from this examination project to calculate which categories or stations having the largest surcharges. This analysis model can be applied on a surcharge on a certain bus model, or it can be used to calculate the surcharge for a certain customer customization

  • 261.
    Nilsson, Henric
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
    UV-tork - analys av drift:  2012Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
  • 262.
    Nordberg, Marcus
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Materialflödesanalys och layoutförslag Volvo Penta AB Varafabriken: Avdelning bearbetning, motorprov, målning och pack2013Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [sv]

    Detta är ett examensarbete vid Karlstad Universitet vårterminen 2013. Arbetet omfattar 22,5 hp, fakulteten för hälsa teknik- och naturvetenskap, högskoleingenjör inom maskinteknik.

     

    Arbetet har utförts på Volvo Penta AB Varafabriken i Västergötland. Volvo har ett behov att se över sin layout över fabriken och de interna materialflödena. Deras layout är gjord efter förutsättningar som rådde för 10 år sedan. En hel del förändringar har skett sedan dess och med ett nytt materialtänk som bygger på Lean-filosofin med bland annat minskade materialfasader, supermarkets och omplock.

    Fokus i arbetet ligger på att minska den tunga gaffeltruckskörningen i fabriken. Visionen Volvo själva har är att använda sig av mindre dragtruckar i så stor utsträckning som möjligt för att kunna effektivisera materialflödena. Förutom att transport är ett stort slöseri är det även en säkerhetsfråga då man inte vill ha tung körning där personal står och arbetar.

    Detta arbete har fokuserat på avdelningarna bearbetning, motorprov och måleri & pack.

     

    Första som gjordes var att ta fram en nulägesanalys. Detta för att få en koll på hur materialflödena går och hur ofta. Spaghettischema ritades upp och en frekvensanalys gjordes på hel- och halvpallar som användes på berörda avdelningar. Även önskemål om att utföra en enklare simulering framkom från Volvo vilket gjordes. Detta visade sig ge en bra uppfattning om hur truckbeläggningen ser ut angående berörda artiklar.

    En viktig del i detta skede var att identifiera sig av brister som rådde i materialflödena. Här fanns en hel del och här upptäcktes det att allt inte är layoutrelaterat. Arbetssättet var en bidragande orsak till mycket onödig körning som görs.

     

    När det kom till framtagande av ny layout kom Volvo med några starka önskemål. Att införa en ny huvudtrafikled genom fabriken var av stor vikt. Flytta på maskiner är inte aktuellt då det inte är försvarbart rent ekonomiskt. Det som kunde flyttas på var pallställage, supermarkets, omplock samt monteringen.

    Dessa önskemål togs givetvis med och tillsammans med ändrat arbetssätt påvisar detta arbete att den tunga gaffeltruckskörningen kan halveras per dag med den nya framtagna layouten (bilaga 3). Detta medför dock att vissa artiklar läggs om på dragtruckar samt att personalen tar mer ansvar och ändrar i några rutiner.

    Layouten gjordes mycket för att underlätta för dragtruckarna i framtiden då Volvo vill att de skall hantera mer artiklar internt än vad som görs idag.

     

    Ett arbete gjordes parallellt med detta med fokus på monteringslinjerna och en ny utbyggnad på fabriken av Markus Andersson.

  • 263. Nordström, Johan
    et al.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Cemented carbides and high speed steels in green wood cutting2005Other (Other (popular science, discussion, etc.))
  • 264. Nordström, Johan
    et al.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Modelling of tooth edge wear in green wood cutting2005Other (Other (popular science, discussion, etc.))
  • 265. Nordström, Johan
    et al.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    The influence of tooth bite and cutting speed on wear of swaged saw teeth in timber cutting2002Conference paper (Refereed)
  • 266. Nordström, Johan
    et al.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Wear testing of saw teeth in timber cutting2001Other (Other (popular science, discussion, etc.))
  • 267.
    Norrby, Alexander
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Nanotribological characterization of advanced tool steels2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

       Tribological  problems  of  tool–work  piece  interaction  is  a  key  aspect  influencing  product quality,  process  performance  and  tool  lifetime.  For  example,  in  sheet  metal  forming operations, sliding contact may cause adhesive wear of sheet materials with build up of worn material on the tool surface. This tribological problem often resulted in loss of tolerance and product quality and is called galling.  

       It  was  demonstrated  that  tendency  to  adhesive  wear  depends  on  the  steel  grade,  which means high importance of chemical- and phase-constitution of the tool steel. It was suggested that  adhesion  to  the  matrix  is  critical  due  to  metal  to  metal  contact  while  carbide  phase prevent adhesion of conterbody materials. Nevertheless, in macroscale tests it is difficult or even impossible to separate contribution of each phase into the wear mechanism.   

       In the present work, selected steels are to be investigated  at nanoscale by means of AFM facilities. Main attention will be paid on adhesion and frictional properties of steel matrix and primary  phase.  As  expected  and  reported  in  several  articles,  carbides,  carbonitrides  and nitrides   may   behave   differently,   contributing   into   the   final   performance   differently. Additional  attention  will  be  paid  on  phase  size  and  distribution,  meaning  they  are  also important parameters influencing tribological behaviour.

  • 268. Nygårds, M
    et al.
    Just, M.
    Hallbäck, Nils
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Tryding, J.
    A finite Element Model for simulations of Creasing and Folding of PaperBoard2005Conference paper (Refereed)
  • 269.
    Ohlsson, Jonas
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Effects of different heat treatments on hardness of Grade 91 steel2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    CCI Valve Technology AB is a company located in Säffle, Sweden, that manufactures and installs bypass valves. Due to requirements outside normal standards on the valve's hardness values, some measurements have had difficulties meeting such requirements. During this thesis work, tests were carried out to determine how to overcome the difficulties. The experiments focused on five different areas that may affect the components hardness, welding method, soaking temperature during post weld heat treatment, measuring procedure, component thickness and number of heat treatment cycles. The Grade 91 steel specimens that were examined consisted of five solid cylinders and three various pipes that were welded together by using shielded metal arc welding (SMAW) or gas tungsten arc welding (GTAW). Each pipe was sawed apart into three equal parts. All specimens were hardness tested and eight of the specimens' microstructure was studied with an optical microscope. The hardness measurement instruments used, LECO V-100-C2 and GE-MIC 10, are Vickers hardness testers, one stationary and the other one portable. The measuring results contain a vast number of different hardness measurement data. From the analyzed data, the conclusions were drawn that the most suitable soaking temperature during post weld heat treatment were 750° C, that the SMAW method creates a more stable hardness profile than the GTAW method, and that one heat treatment cycle is more beneficial than two or more.

  • 270.
    Olofsson, Fredrik
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Modularisering av konstruktionsunderlag2012Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Volvo Buses in Säffle produces most of the customized buses within the Volvo group. As a result of the customizations additional hours in the bus assembly process for seat mounting has to be spent, and sometimes even additional design hours, during the tender process which is in 2D-CAD. The current methods and tools together with short lead time for the tenders are not accurate enough.

    The objective from Volvo is to develop a parametric seat positioning module in 3D-CAD. The module should also include parameters for construction of the bus floor.

    The parametric module has to be faster and more reliable than the current methods in 2D-CAD. Therefore the adjustments of the layout’s significant dimensions have to be done easily. The module also needs to regard safety rules and legal requirements.

    The developing of the parametric module is divided in three parts; floor module, seat positioning module and reduction of file size for the seat model. The construction of the modules will use the methodology from Top-down as main structure.

    The project resulted in three different parametric modules, one for each bus type that was analyzed during this project.

  • 271. Persson, A.
    et al.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Burman, Christer
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Evaluation of heat checking damage in die casting1999Conference paper (Refereed)
  • 272. Persson, A
    et al.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Burman, Christer
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Hogmark, S
    Experimental Investigation n thermal fatigue of a surface engineered hot work tool steel2001Conference paper (Refereed)
  • 273. Persson, A
    et al.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Burman, Christer
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Hogmark, S
    Influence of deposotion temperature and time during PVD coating of CrN on corrosive wear in liquid aluminium2001In: Surface and coatings Technology, 146-147, 2001, 42Article in journal (Refereed)
  • 274. Persson, A
    et al.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Hogmark, S
    Influence of surface engineering on the performance of tool steels for die casting2002In: / [ed] J Bergström, G Fredriksson, M Johansson, O Kotik, F Thuvander, 2002Conference paper (Refereed)
  • 275. Persson, A
    et al.
    Hogmark, S
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Failure modes in field-tested brass die casting dies2003Other (Other (popular science, discussion, etc.))
  • 276. Persson, A
    et al.
    Hogmark, S
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Simulation and evaluation of thermal fatigue cracking of hot work tool steels2004In: International Journal of Fatigue, Volume 26, Number 10, 2004Article in journal (Refereed)
  • 277. Persson, A
    et al.
    Hogmark, S
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Temperature profiles and conditions for thermal fatigue cracking in brass die casting dies2004In: Journal of Materials Processing Technology, v 152, n2, 2004Article in journal (Refereed)
  • 278. Persson, A
    et al.
    Hogmark, S
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Thermal fatigue cracking of surface engineered hot work tool steels2005In: Surface and Coatings Technology, volume 191, Issues 2-3, 21 February 2005Article in journal (Refereed)
  • 279.
    Persson, Edvin
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
    Krabba: Automatisk pallkragsmontering2012Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    The company Goodtech Solutions AB has developed a prototype. This prototype is a machine that automatically can assemble pallet collars on pallets with the help of a robot. The prototype needs to undergo some improvements and this work focus on the unit that handles the pallet collar during the assembling. This unit is called crab because of its design. The objective of this work is to accomplish the improvements and the purpose is to be a basis for all the improvements that the machine could undergo before a market release.

    To assemble a pallet collar the crab locks the pallet collar after it’s received from the robot. Then it bends the hinges and mounts the pallet collar onto a pallet. The crab’s main problems are the adjustments before handling the pallet collar and to correct the crab’s position in relation to the outer collar before assembling. This is because all adjustments are in relation to the center of the crab and that the crab pushes out the four corners when locking the pallet collar. To bend the hinges the crab uses a method that’s similar to a quick hammer stroke and this method is considered uncontrolled. A customer requirement emerged during the project. The customer requirement was that the machine should handle the bigger Volvo L pallet collar in addition to the EUR pallet collar.

    Because the crab should handle two different sizes of pallet collars the new concept would be for a new design. Therefor the work was limited to only include the crab. The attachment of the crab to the structure and the drive during assembly were excluded. Because of these restrictions the new crab must have the same movements as the present crab to collaborate with the rest of the machine.

    In the new concept two sides of the crab are fixed, one long and one short side, and the other two are variable. The two variable sides push outwards in a linear direction to lock the pallet collar. With two sides fixed all adjustments can relate to their corner as it is an origo. The crab remains in this fixed position because of the origo but the outer collar can adjust to this origo. This new concept appears to be better for adjustments because of the origo and that only two sides can vary. To bend the hinges there are four units in each corner. The units bend the hinges with a linear movement and an anvil so the forces can be absorbed locally. These units can vary their positions to handle both the EUR pallet collar and the Volvo L pallet collar. The linear movement to bend the hinge is considered stable.

    During the design of this concept the choices of components, material, material dimensions are based on rough estimates and oversizing due to the machine being a prototype. The crab was designed foremost with parts and profiles in construction steel. Hydraulic cylinders were used to bend the hinges. Pneumatic cylinders and ball rail systems were used to lock the pallet collar and other movements.

    This new concept and its design have improved the crab and extended its functionality. Therefor the objective and purpose of this work is considered to be achieved. Work still remaining is more precise estimates of material dimensions and components. The attachment in the structure and the drive during assembling should be looked over to make sure the crab is compatible with the rest of the machine.

  • 280.
    Phan, Kong
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Innovativa modulmöbler för barn: En möbellösning som möter barnens fantasi och motorikutveckling genom lek och byggande2014Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    This project assignment is done on behalf of the innovator Ludmila Kompaniets. The project is included in the compulsory for the course MSGC12 - Degree of Bachelor of Science in Innovation and Design at the Faculty of health, nature and Engineering Sciences at Karlstad University.

    The innovator Ludmila Kompaniets with many years experience as a preschool teacher found a need for children to have their own privacy in preschool environment.

    The anchoring made to the curriculum highlighted the lack of work on the physical environment in preschools.

    Ludmila Kompaniets with her idea are intent to help children stimulate their senses and further develop their motor skills indoors during their pre-school years. For this to be possible, she used the children's curiosity and playfulness. The idea is based on a group of innovative modulation furniture that will allow children to independently use their creativity in building furniture with safety.

    Interviews together with observations in preschools in Karlstad district have been analyzed and showing rather poorly results.

    The concept generation took place in two rounds, the first concept generation session was with people who have influence in the profession with children. Second session was with a group of children, this to observe how children think in concrete form. Both sessions yielded a number of concept solutions, which are then eliminated and evaluated. At the final step through spiderweb chart the selection appointed to the selected concepts that are best suited to the product specification and according to the project owner's intentions.

    The concept solution’s simple but abstract forms are challenging to the target group’s different senses, senses that the children need to outbreak in order to learn and be stimulated. The solution provides the children to separate from stress -related causes such as noise and large groups. The concept solution also provide modulation that challenge children's motor skills.

    Material proposal for the concept is applicable and is already prepared on the market for the target group, the manufacturing method is simple and has a relatively low cost. Cost of materials and manufacturing should be examined in a larger extent.

    A full-scale prototype should be tested with the target audience in order to investigate how well the solution meets the issue.

  • 281.
    Runling, André
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Evar: En produktutveckling och formgivning av cykelbelysning med LED som ljuskälla2013Independent thesis Advanced level (professional degree), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Evar is a project degree of 22,5 ECTS credits individually carried out by André Runling during the spring of 2012 at Karlstad University, for a bachelor degree in Innovation technique and Design engineering. The assigner for this project is Johan Larsvall, industrial designer and owner of Idesign in Stockholm. Academic supervisor at Karlstad University has been Lennart Wihk, industrial designer and university lecturer. Examiner has been Fredrik Thuvander, professor and university lecturer.

    Idesign is a design agency with office on Longholmen in central of Stockholm and is assigned by different companies in different sectors such as, Silva Sweden AB and Trafikverket.

    Idesign got the task from Trafikverket to make suggestions to concepts of bike lights that increase the use and reliability compared to todays use. The project was initiated by Trafikverket while Idesign were responsible of developing a bike light to Silva. Silva has specialised themselves in head lamps for many years and have seen an opportunity to reach a new market with the collaboration, which resulted in this degree project and development primary to Idesign.

    The projects first part was to study what is inadequate in today's lighting and why it is not used as much as it should. The study was conducted with a poll and discussions on Swedish forums on the internet. A large part of the project was to compare why the usage looks different and is used more often in Denmark, and also Germany. Germany has a detailed approval of bicycle lights in their traffic regulations which was needed to be interpreted.

    Using the information gathered, a development of concepts started to a bicycle light that exudes simplicity and appeal to a commuting cyclist, with the idea generation method and product specification which was evaluated in a matrix. Of three concepts that were presented to Idesign, one concept was selected for further processing which developed into a final proposal and description of a bicycle light.

    The final solution means that the head lamp is powered by a battery, and notifies with a battery indicator when it needs charging, directly into a electrical outlet. With a simple single-hand grip it’s connected in the bracket and, in its turn a buckle, which is mounted steplessly on the bicycle by a strap. It means it can be mounted on any bicycle. While the rear light is supposed to always sit on, have the same type of installation and have an automatic on and off switch via a light and motion detector. It still has a battery indicator to se when batteries should be replaced. Both the front and the rear light is equipped with LED for lighting.

  • 282. Rättö, P.
    et al.
    Barbier, Christophe
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Health, Science and Technology (starting 2013), Paper Surface Centre. Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Rigdahl, M.
    An investigation of the friction properties of coated paper2000In: Nordic Pulp and Paper Research JournalArticle in journal (Refereed)
  • 283.
    Sadek, Mohamed
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Datorstödd simulering och FEM-analys av öppen lednyckel2011Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This project contains calculations and material analysis on a newly invented type of socket wrenches, Open socket wrench. The calculation part is consists of computer-aided simulation and FEM-analysis of stresses and elongations in the material. For that the computer software ABAQUS/CAE will be used. There are two different kinds of Open socket wrenches which are separated by a small difference in the construction, but the function is the same. Of each type two sizes will be investigated in this project. A research of critical regions regarding stresses and elongations will be made on the results. A research of a material which is able to resist the arisen stresses without getting plastically deformed also will be made. The material needs to have tensile yield strength as high as the highest arisen stresses in the critical regions. The chosen material is SSAB´s TOOLOX 44, which is a tool steel with tensile yield strength at 1300 MPa. The most important thing regarding the elongations is that the opening of the socket doesn’t gets stretched that much so the socket loses grip of the nut/screw head. The simulation result shows that the elongation is small enough to consider the risk of that the socket will lose grip is very small.

  • 284.
    Sadek, Mohamed
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Design and development of a testing device for a new invented Doctor Blade2013Independent thesis Advanced level (degree of Master (Two Years)), 300 HE creditsStudent thesis
    Abstract [en]

    This thesis project is about designing and developing an already existing testing device for a new invented Doctor Blade. A doctor blade is a blade used for creping tissue paper of a rotating cylinder, Yankee Cylinder. The old testing device was incomplete in a way that a rotating cylinder was missing, hence the tested blade is not loaded properly. The old testing device already contained the doctor blade holding device and the pulling device (pulling the creping blade). These two devices are transferred to the new testing device without any redesign within them. The adding of a rotating cylinder/roller required some new redesign regarding the testing device.

    The main beam (beam carrying all elements) is replaced with a larger one in order to fit the roller and is elongated in order to run longer tests. The new beam has a larger cross section in order to minimize the risk of bending.

    The main beam is supplied with five small beams, welded onto it, three for attaching the holding device and two for attaching the roller. The dimensions of these small beams are chosen in order to put the roller on the right position according to the creping blade.

    An electric motor is added to the new testing device in order to drive the roller with a chain. This required two sprockets, one for the motor and one for the roller shaft. The sprockets are chosen with a pitch diameter ratio matching the gearing required.

    FMEA-analysis is done on the whole design where five failure modes were chosen to be included, bending of the main beam and motor beam, screw joints of the same beams and sprocket-chain mechanism. Some FEM-analysis was required in order to detect the bending of the beams and measuring the loading on the screw joints. The screw joint loading achieved from the FEM-analysis is used for the theoretical screw joint calculations.

    The FMEA-analysis implied that four of the analyzed failure modes have acceptably low risk factor and dos not require any further actions. However one received a high risk factor, the chain-sprocket mechanism, the risk of clamping fingers. This is solved by adding a protecting house/shell made of sheet metal.

    Measurements were done on the old and the new testing device regarding the required force for pulling the creping blade and the pressure distribution between the creping blade and the beam (and roller in the new testing device).

    The improvement of the pulling force values is rather due to the new designed doctor blade than due to the new testing device. The new testing device is however more appropriate than the old one hence the added roller and the tests shows that it is functional as well. 

  • 285.
    selvaraj nadar, vighneish
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Fatigue testing of scratched flapper valve steel2014Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    A flapper valve is made from a hardened and tempered high strength strip steel which opens and shuts as it is subjected to very high cyclic loads. Steel strip of which flapper valves are made from can   encounter a surface defect which are anticipated to influence fatigue life negatively. In this study, the influence of surface scratches on fatigue life of flapper valve strip was investigated. The analysis was carried out by using thirty samples that were blanked out of eight different steel strips in the transverse direction. Of these samples, fifteen of them had scratches on the surface and fifteen did not, all these samples were fatigue tested by constant amplitude method. An S-N curve was plotted based upon the values and results from the fatigue test, considering the curve as the nerve center in relation with fractrographic studies using the Scanning electron microscope. Therefore this master thesis work aims to explain the influence of scratches on fatigue life of flapper valve strip and suggest future improvements based on the findings.

  • 286.
    Sjöman, Joakim
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Cold drawing of tool steels2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Present study is a master thesis in materials engineering and has been performed at Karlstad University and at Uddeholms AB in Hagfors. Uddeholms AB has recently seen a new request from customers, of smaller dimensions of round bars than covered by Uddeholms AB’s dimension program. To get these smaller dimensions Uddeholms AB has up till now, used help from other companies to hot roll and peel the material to the desired dimension. A more efficient way could be to use a cold drawing process on these bars to the desired dimensions.

    The main objectives of this study were to find nearby companies which have suitable draw benches and to find how the material is affected by a cold drawing process. This was performed by a market investigation followed by a technical investigation. The investigated material was Uddeholm THG 2000.

    Cold drawing is an operation in which the cross section of a bar, rod or wire is reduced by pulling it through a die opening. It was soon found that in the desired dimension range the common way to perform this is from wire coil and not from straight bars. This reduced the suitable companies for the Uddeholm THG 2000 bars greatly.

    Some of the conclusions from the present study are:

    • Cold drawing of bar to bar is not the normal practice in the desired dimension range. Only three suitable companies were found to be able to perform bar to bar drawing, Boxholm Stål AB, Kiveton Park Steel and Erasteel Champagnole.
    • THG 2000 could be drawn from Ø25 mm to Ø10 mm, but this would require as many as 8-10 drawing processes, with annealing heat treatments between every second drawing process. This would not be economically efficient, but could result in an extremely fine grain size.
    • The cold drawing process of small dimensions affects the entire cross section of the material. 
    • The direct effects (hardness and internal stress) of a cold drawing operation will disappear in the quench and temper treatment, and in that aspect there are no differences between cold drawn and hot rolled material. Anyhow, indirect effects such as grain size and material distortion can affect material properties even after a quench and temper heat treatment.
  • 287. Sjöström, Johnny
    et al.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Cyclic behaviour modelling of hot-work tool steels at high temperature fatigue2004Other (Other (popular science, discussion, etc.))
  • 288. Sjöström, Johnny
    et al.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Evaluation of the cyclic behaviour during high temperature fatigue of hot work tool steels2002In: / [ed] J Bergström, G Fredriksson, M Johansson, O Kotik, F Thuvander, 2002Conference paper (Refereed)
  • 289. Sjöström, Johnny
    et al.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Microstructural stability and strength of chromium martensitic hot-work tool steels2004Other (Other (popular science, discussion, etc.))
  • 290. Sjöström, Johnny
    et al.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    On the influence of austenitizing treatment on isothermal and thermal fatigue lives of hot-work tool steels2003Other (Other (popular science, discussion, etc.))
  • 291. Sjöström, Johnny
    et al.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Thermal fatigue testing of chromium martensitic hot-work tool steel after different austenitizing treatments2004In: Journal of Materials Processing Technology, 153-154, 2004Article in journal (Refereed)
  • 292. Sjöström, Johnny
    et al.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Thermal fatigue testing of chromium martensitic hot-work tool steel after different austenitizing treatments2003In: / [ed] A G Oblai, M S J Hashmi, 2003Conference paper (Refereed)
  • 293.
    Stenkvist, Niklas
    Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Design of a cargo fastening device with a load indicator for heavy cargo2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The aim of this thesis was to develop a new turnbuckle for fastening containers on cargo ships. The design was supposed to indicate whether the turnbuckle could be re-used, i.e. it hadn't plastically deformed. This indication could reduce the risk of a turnbuckle breaking during transport, since turnbuckles that have been exposed to a load above their safe working load would indicate this. \newline In total 25 different concepts were developed and put through two different elimination matrices which were evaluated against a requirement specification. The final design had calculated stress of 630 MPa at breaking load and 472 MPa proof load, the loads are defined by Germanischer Lloyd. A concept for measurement of the deformation of the turnbuckle was developed, however it is in need of further development and testing before it can be implemented. A suggestion of manufacturing method, material and surface treatment has been given, but prototype testing is required to verify the design and ensure adequate corrosion protection.

  • 294. Sundqvist, Martin
    et al.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Björk, T
    Westergård, R
    Corrosive Wear of duplex coatings in die casting of aluminum1997Other (Other (popular science, discussion, etc.))
  • 295. Svenningsson, R
    et al.
    Bergström, Jens
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Krakhmalev, Pavel
    Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Tool life in sliding wear on high strength stainless steel sheets (poster WOM 2007)2007Other (Other (popular science, discussion, etc.))
  • 296.
    Thuvander, Fredrik
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Paper Surface Centre. Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    A new measurement technique for studies of paper surfaces2003Other (Other (popular science, discussion, etc.))
  • 297.
    Thuvander, Fredrik
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Paper Surface Centre. Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Fracture Behaviour of Green Wood, A Composite Materials Approach1998Report (Other academic)
  • 298.
    Thuvander, Fredrik
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Paper Surface Centre. Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Wood Cell-Wall damage: A Composite Materials Approach1996Report (Other academic)
  • 299.
    Thuvander, Fredrik
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Paper Surface Centre. Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Berglund, L A
    A multiple fracture test for strain to failure distribution in wood1998In: Wood Sci and Technology 32 1998 pp 227-235Article in journal (Refereed)
  • 300.
    Thuvander, Fredrik
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Paper Surface Centre. Karlstad University, Faculty of Technology and Science, Materials Science. Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
    Berglund, L A
    Cell wall damage induced by drying -a composite materials approach1999Other (Other (popular science, discussion, etc.))
34567 251 - 300 of 330
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