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  • 1.
    Bolmsjö, Gunnar
    et al.
    Linnaeus University, Växjö, Sweden.
    Ferreira Magalhães, Ana Catarina
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS). Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Cederqvist, L.
    SKB AB, Oskarshamn, Sweden.
    De Backer, Jeroen
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Robotic Friction Stir Welding of complex geometry and mixed materials2018Ingår i: 50th International Symposium on Robotics, ISR 2018, VDE Verlag GmbH , 2018, s. 35-41Konferensbidrag (Refereegranskat)
    Abstract [en]

    Friction stir welding (FSW) is a solid state process for joining materials which has demonstrated advantages compares with other methods which include joining of mixed materials, hard to weld alloys and consistent and high quality. This paper presents a study of robotic FSW initiated by Volvo Skövde plant to join an insert workpiece of extruded aluminium with a cylinder block of aluminium casting. A three-stage procedure was decided to determine the feasibility to apply robotic FSW. The stages included study of welding the mixed materials, weld along the complex joint line with holes and channels close to the joint, and finally welding the cylinder block. The results based on preliminary analysis indicate that the final tests were successful and the process is feasible for the challenging case study. However, further studies are recommended in order to identify the operating parameters window, tool design, and control of the process in order to optimize productivity and quality. © VDE VERLAG GMBH

  • 2.
    De Backer, Jeroen
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för automationssystem.
    Feedback Control of Robotic Friction Stir Welding2014Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    The Friction Stir Welding (FSW) process has been under constant developmentsince its invention, more than 20 years ago. Whereas most industrial applicationsuse a gantry machine to weld linear joints, there are applications which consistof complex three-dimensional joints, requiring more degrees of freedom fromthe machines. The use of industrial robots allows FSW of materials alongcomplex joint lines. There is however one major drawback when using robotsfor FSW: the robot compliance. This results in vibrations and insufficient pathaccuracy. For FSW, path accuracy is important as it can cause the welding toolto miss the joint line and thereby cause welding defects.The first part of this research is focused on understanding how welding forcesaffect the FSW robot accuracy. This was first studied by measuring pathdeviation post-welded and later by using a computer vision system and laserdistance sensor to measure deviations online. Based on that knowledge, a robotdeflection model has been developed. The model is able to estimate thedeviation of the tool from the programmed path during welding, based on thelocation and measured tool forces. This model can be used for online pathcompensation, improving path accuracy and reducing welding defects.A second challenge related to robotic FSW on complex geometries is thevariable heat dissipation in the workpiece, causing great variations in the weldingtemperature. Especially for force-controlled robots, this can lead to severewelding defects, fixture- and machine damage when the material overheats.First, a new temperature method was developed which measures thetemperature at the interface of the tool and the workpiece, based on the thermoelectriceffect. The temperature information is used as input to a closed-looptemperature controller. This modifies primarily the rotational speed of the tooland secondarily the axial force. The controller is able to maintain a stablewelding temperature and thereby improve the weld quality and allow joining ofgeometries which were impossible to weld without temperature control.Implementation of the deflection model and temperature controller are twoimportant additions to a FSW system, improving the process robustness,reducing the risk of welding defects and allowing FSW of parts with highlyvarying heat dissipation.

    Ladda ner fulltext (pdf)
    PhD Thesis - Feedback Control of Robotic Friction Stir Welding
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    fulltext
  • 3.
    De Backer, Jeroen
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för elektro- och automationsteknik.
    Robotic Friction Stir Welding for Flexible Production2012Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Friction Stir Welding eller ”friktionsomrörningssvetsning” är en svetsprocess som kräver ett roterande verktyg som genom friktionsvärme får materialet att mjukna. Verktyget blandar runt det plastiska materialet mekaniskt och skapar en fog av hög kvalité. Processen fungerar utan gas, utan rök, utan tillsatsmaterial och utan att smälta materialet. Alla dessa fördelar skapar stort industriellt intresse inom flera branscher. Idag används tekniken nästan uteslutande i styva maskiner som svetsar raka eller cirkulära fogar och framförallt för aluminium. Eftersom processen kräver stora krafter mellan material och verktyg är det svårt att implementera processen på en robot. En robot möjliggör svetsning av tredimensionella geometrier och ökar dessutom flexibiliteten.  Flera forskargrupper runt i världen har tagit fram en fungerande FSW robot som kan svetsa tunn lättviksmaterial som aluminium med hög kvalitet. Användningen i industrin av FSW robotar är däremot obefintlig och det finns ett antal anledningar till det. Först är roboten vek vilket gör att verktyget kan missa svetsfogen i hårda material och svetsdefekter kan uppstå. En annan anledning är at det inte finns en användbar automatiserad processtyrning tillgänglig, mest för att FSW är en robust process och inte kräver en avancerad styrning vid svetsning av raka fogar.

    De praktiska arbeten som redovisas i denna licentiatuppsats är huvudsakligen utförda i en robotiserad FSW-demonstrator på Högskolan Väst. FSW-roboten är en modifierad industrirobot som är försetts med spindel och kraftåterkoppling för att styra kraften som roboten applicerar på arbetsstycket.

    Detta arbete har identifierat ett antal problem som behöver lösas för att få en robust robotiserad FSW process i en flexibel produktionsmiljö. I denna licentiatrapport beskrivs en lösning hur en typ av svetsdefekter kan förhindras genom en sensorbaserad bankompensering. Både en kamera- och lasersensor-baserad mätmetod presenteras. En annan bankompenseringsstrategi är beskriven, som använder kraftsensorn från befintlig kraftåterkoppling istället för att lägga till extra sensor. Denna strategi kan utvecklas till en komplett utböjningsmodell på roboten i hela arbetsområdet. Robotens begränsningar gällande svetsbarhet av hårda material har undersökts och med hjälp av parameteroptimering och förvärmning kan även hårda nickelbaserade legeringar svetsas med roboten.

  • 4.
    De Backer, Jeroen
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för automation och datateknik.
    Bolmsjö, Gunnar
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för automation och datateknik.
    Deflection model for robotic friction stir welding2014Ingår i: Industrial robot, ISSN 0143-991X, E-ISSN 1758-5791, Vol. 41, nr 4, s. 365-372Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose - This paper aims to present a deflection model to improve positional accuracy of industrial robots. Earlier studies have demonstrated the lack of accuracy of heavy-duty robots when exposed to high external forces. One application where the robot is pushed to its limits in terms of forces is friction stir welding (FSW). This process requires the robot to deliver forces of several kilonewtons causing deflections in the robot joints. Especially for robots with serial kinematics, these deflections will result in significant tool deviations, leading to inferior weld quality. Design/methodology/approach - This paper presents a kinematic deflection model, assuming a rigid link and flexible joint serial kinematics robot. As robotic FSW is a process which involves high external loads and a constant welding speed of usually below 50 mm/s, many of the dynamic effects are negligible. The model uses force feedback from a force sensor, embedded on the robot, and predicts the tool deviation, based on the measured external forces. The deviation is fed back to the robot controller and used for online path compensation. Findings - The model is verified by subjecting an FSW tool to an external load and moving it along a path, with and without deviation compensation. The measured tool deviation with compensation was within the allowable tolerance for FSW. Practical implications - The model can be applied to other robots with a force sensor. Originality/value - The presented deflection model is based on force feedback and can predict and compensate tool deviations online.

  • 5.
    De Backer, Jeroen
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för automation och datateknik.
    Bolmsjö, Gunnar
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för automation och datateknik.
    Thermoelectric method for temperature measurement in friction stir welding2013Ingår i: Science and technology of welding and joining, ISSN 1362-1718, E-ISSN 1743-2936, Vol. 18, nr 7, s. 541-550Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Previous research within friction stir welding (FSW) has demonstrated that online control of welding parameters can improve the mechanical properties and is necessary for certain applications to guarantee a consistent weld quality. One approach to control the process is by adapting the heat input to maintain a stable welding temperature, within the specified operating boundaries. This requires accurate in-process temperature measurements. This paper presents a novel method to measure the temperature at the interface of the FSW tool and workpiece. The method is based on the thermoelectric effect between dissimilar materials. The measurements are compared to thermocouple measurements and to a physical model and show good correspondence to each other. Experiments demonstrate that the method can quickly detect temperature variations, due to geometrical variations of the workpiece or due to parameter changes. This allows use of the method for online control of robotic FSW.

  • 6.
    De Backer, Jeroen
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för automation och datateknik.
    Bolmsjö, Gunnar
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för automation och datateknik.
    Christiansson, Anna-Karin
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för automation och datateknik.
    Temperature control of robotic friction stir welding using the thermoelectric effect2014Ingår i: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 70, nr 1-4, s. 375-383Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Friction stir welding (FSW) of non-linear joints receives an increasing interest from several industrial sectors like automotive, urban transport and aerospace. A force-controlled robot is particularly suitable for welding complex geometries in lightweight alloys. However, complex geometries including three-dimensional joints, non-constant thicknesses and heat sinks such as clamps cause varying heat dissipation in the welded product. This will lead to changes in the process temperature and hence an unstable FSW process with varying mechanical properties. Furthermore, overheating can lead to a meltdown, causing the tool to sink down into the workpiece. This paper describes a temperature controller that modifies the spindle speed to maintain a constant welding temperature. A newly developed temperature measurement method is used which is able to measure the average tool temperature without the need for thermocouples inside the tool. The method is used to control both the plunging and welding operation. The developments presented here are applied to a robotic FSW system and can be directly implemented in a production setting.

  • 7.
    De Backer, Jeroen
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för automationssystem.
    Christiansson, Anna-Karin
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för automationssystem.
    Surface Quality and Strength in Robotic Friction Stir Welding of Thin Automotive Aluminium Alloys2011Ingår i: The 4th International Swedish Production Symposium / [ed] Jan-Eric Ståhl, The Swedish Production Academy , 2011, s. 554-562Konferensbidrag (Refereegranskat)
    Abstract [en]

    Friction Stir Welding (FSW) is a novel method for joining materials without using consumablesand without melting the materials. It uses a rotating tool that creates frictionalheat and mixes the materials mechanically together. Robotic application of FSW allowsthree-dimensional welding of light-weight metals in e.g. the automotive industry. TheStiRoLight project is driven by Saab Automobile AB and performed at University Westfor investigation of robotic FSW of three-dimensional welding seams. It aims to introduceFSW in the automotive production line. This paper describes the effect of penetrationdepth of the FSW tool during force controlled robotic welding of thin (< 2 mm) aluminium inoverlap configuration. The influence of pin length on strength of welded aluminium sheetsis investigated using tensile and peel tests. The main limiting factor for penetration depthis the surface quality on the backside of the weld, which often is important in automotiveapplications. Further, the roughness of the plates on the backside is measured and relatedto pin length and backing bar properties. This paper shows a relation between penetrationdepth and tensile strength, and suggests an optimal pin length to guarantee a good weldquality while maintaining an acceptable surface quality. The influence of sheet thicknesstolerance is also discussed. Knowledge is fed back to designers and manufacturingengineers to facilitate for use in production with guaranteed product quality.

  • 8.
    De Backer, Jeroen
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för elektro- och automationsteknik.
    Christiansson, Anna-Karin
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för process- och produktutveckling.
    Oqueka, Jens
    Högskolan Väst, Institutionen för ingenjörsvetenskap.
    Bolmsjö, Gunnar
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för automation och datateknik.
    Investigation of path compensation methods for robotic friction stir welding2012Ingår i: Industrial robot, ISSN 0143-991X, E-ISSN 1758-5791, Vol. 39, nr 6, s. 601-608Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose – Friction stir welding (FSW) is a novel method for joining materials without using consumables and without melting the materials. The purpose of this paper is to present the state of the art in robotic FSW and outline important steps for its implementation in industry and specifically the automotive industry.

    Design/methodology/approach – This study focuses on the robot deflections during FSW, by relating process forces to the deviations from the programmed robot path and to the strength of the obtained joint. A robot adapted for the FSW process has been used in the experimental study. Two sensor-based methods are implemented to determine path deviations during test runs and the resulting welds were examined with respect to tensile strength and path deviation.

    Findings – It can be concluded that deflections must be compensated for in high strengths alloys. Several strategies can be applied including online sensing or compensation of the deflection in the robot program. The welding process was proven to be insensitive for small deviations and the presented path compensation methods are sufficient to obtain a strong and defect-free welding joint.

    Originality/value – This paper demonstrates the effect of FSW process forces on the robot, which is not found in literature. This is expected to contribute to the use of robots for FSW. The experiments were performed in a demonstrator facility which clearly showed the possibility of applying robotic FSW as a flexible industrial manufacturing process.

  • 9.
    De Backer, Jeroen
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS). TWI Ltd, Cambridge, UK.
    Martin, Jonathan
    TWI Ltd, Cambridge, UK.
    Wei, Sam
    TWI Ltd, Cambridge, UK.
    Robotic Stationary Shoulder FSW: benefits and limitations2016Ingår i: Conference proceedings of the 11th International Symposium on Friction Stir Welding, 2016Konferensbidrag (Refereegranskat)
  • 10.
    De Backer, Jeroen
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för elektro- och automationsteknik.
    Soron, Mikael
    ESAB Welding AB .
    Three-dimensional friction stir welding of Iconel 718 using the ESAB Rosio FSW-robot2013Ingår i: Trends in Welding Research: Proceedings of the International Conference on Trends in Welding Research, June 4-8, 2012, Hilton Chicago/Indian Lakes ResortChicago, Illinois, USA / [ed] Tarasankar DebRoy, Stan A. David, John N. DuPont, Toshihiko Koseki, Harry K. Bhadeshia, Ohio: ASM International, 2013, s. 829-833Konferensbidrag (Refereegranskat)
    Abstract [en]

    Robotic Friction Stir Welding (FSW) facilitates for increased welding flexibility, and allows for studies of forces in three dimensions without having the high cost of a stiff 5-axes FSW machine. Recent developments in tool materials and welding equipment motivate this study on FSW of high-strength alloys by a robot in a three dimensional workspace. New concepts of aircraft engines suggest higher temperatures to increase engine efficiency, requiring more durable materials such as the nickel-based alloy 718. The ESAB Rosio (TM) FSW robot, used in this study, can deliver up to 15kN downforce and 90Nm torque. This is sufficient for welding high-strength alloys of limited thickness. This study focuses on the process forces during friction stir welding of Inconel 718 with thickness up to 3mm in butt-joint configuration. A newly developed threaded Poly-Crystalline Boron Nitride (PCBN) tool with convex shoulder is used in a local argon-shielded atmosphere. Initial tests are performed in a stiff FSW machine in position controlled mode. The measured process forces in position control are later on used as parameters on the force-controlled robot. Different backing bar materials are investigated with the aim to decrease the risk of root defects. Tool steel and regular inconel backing bars are proven to be too soft for this purpose and alternatives are suggested. The optimal welding parameters are tuned to combine a good weld quality with the process forces that can be obtained by the robot. Preheating is used to further decrease the need of high process forces.

  • 11.
    De Backer, Jeroen
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för elektro- och automationsteknik.
    Soron, Mikael
    ESAB Welding AB .
    Cederqvist, Lars
    Influence of side-tilt angle on process forces and lap joint strength in robotic friction stir welding2012Ingår i: Proceedings 9th International friction stir welding symposium, Huntsville, AL, USA, 15th to 17th of May 2012, 2012, s. CD-Konferensbidrag (Refereegranskat)
  • 12.
    De Backer, Jeroen
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för elektro- och automationsteknik.
    Soron, Mikael
    ESAB Welding AB .
    Ilar, Torbjörn
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för industriell produktion.
    Christiansson, Anna-Karin
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för process- och produktutveckling.
    Friction stir welding with robot for light vehicle design2010Ingår i: Proceedings from the 8th International Friction Stir Welding Symposium: Timmendorfer Strand, Germany 18-20 May 2010, The Welding Institute , 2010Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Reducing weight is one of the enablers to design more environmentally friendly vehicles. Friction Stir Welding (FSW) supports low weight design through its capability to join different combinations of light weight materials, e.g. different aluminium alloys, but also through its possibilities in producing continuous joints. StiRoLight is a recently started project for robotised FSW for joining of light weight materials emphasising on the vehicle industry, an industry with a long-time experience of robotic welding. The first task involves investigation of force feedback for maintaining the desired contact force. Another important aspect in robotised FSW is the compliance of the robot, which may result in deviations from the pre-programmed path as a result of the high process forces experienced during the welding operation. The further exploration of three-dimensional FSW seams and definition of the process windows will be part of further research within this project.

  • 13.
    Ferreira Magalhães, Ana Catarina
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Cederqvist, Lars
    SKB AB, Oskarshamn, Sweden.
    De Backer, Jeroen
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Håkansson, Emil
    Volvo Cars, Göteborg, Sweden.
    Ossiansson, Bruno
    Volvo Cars, Skövde, Sweden.
    Bolmsjö, Gunnar
    Linnaeus University, Växjö, Sweden.
    A Friction Stir Welding case study using Temperature Controlled Robotics with a HPDC Cylinder Block and dissimilar materials joining2019Ingår i: Journal of Manufacturing Processes, ISSN 1526-6125, Vol. 46, s. 177-184Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The automotive industry is going through a radical transformation from combustion engines to fully electric propulsion, aiming at improving key performance indicators related to efficiency, environmental sustainability and economic competitiveness. In this transition period, it is important to continue the innovation of combustion engines for e.g. plug-in hybrid vehicles. This led Volvo Cars to pursue radically new manufacturing processes such as Friction Stir Welding (FSW). The work presented in this paper is a case study whereby feasibility of using FSW to join a reinforcement element into the aluminium casted Cylinder Block was studied. The complex geometry of the joint required a flexible five-axis manipulator, i.e. an industrial robot, as well as advanced process control, i.e. temperature feedback control, in order to maintain a consistent weld quality throughout the whole component. The process was successfully demonstrated in a lab environment and offers a cost-efficient solution while maintaining the durability and higher efficiency. The outcome of this study shows the great potential of implementing the FSW process in combination with High Pressure Die Casted components, such a Cylinder Block. © 2019 The Society of Manufacturing Engineers

  • 14.
    Ferreira Magalhães, Ana Catarina
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS). Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    De Backer, Jeroen
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Bolmsjö, Gunnar
    Linnaeus University, Växjö, Sweden.
    Thermal dissipation effect on temperature-controlled friction stir welding: [Efeito da dissipação térmica inducida durante soldadura por friçcão linear sob controlo de temperatura]2019Ingår i: Soldagem & Inspeção, ISSN 0104-9224, E-ISSN 1980-6973, Vol. 24, artikel-id e2428Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    During Friction Stir Welding (FSW) of complex geometries, the thermal dissipation, induced by geometric features or the surrounding environment, may strongly affect the final weld quality. In order to guarantee a consistent weld quality for different conditions, in-process welding parameter adaptation is needed. This paper studies the effect of thermal dissipation, induced by the backing bar thermal conductivity, on the weld temperature and the temperature controller response to it. A new temperature sensor solution, the Tool-Workpiece Thermocouple (TWT) method, was applied to acquire online temperature measurements during welding. An FSW-robot equipped with temperature control, achieved by rotation speed adaptation, was used. AA7075-T6 lap joints were performed with and without temperature control. The cooling rate during welding was register plus macrographs and tensile tests were assessed. The controller demonstrated a fast response promoting the heat input necessary to maintain the set welding temperature. The results demonstrated that temperature control using the TWT method is suitable to achieve higher joint performance and provides a fast setup of optimal parameters for different environments. © 2019, Universidade Federal de Uberlandia. All rights reserved.

    Ladda ner fulltext (pdf)
    fulltext
  • 15.
    Ferreira Magalhães, Ana Catarina
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    De Backer, Jeroen
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS). TWI Ltd. Cambridge, UK.
    Martin, Jonathan Peter
    TWI Ltd. Cambridge, UK.
    Bolmsjö, Gunnar
    Linnaeus University, Växjö, Sweden.
    In-situ temperature measurement in friction stir welding of thick section aluminium alloys2019Ingår i: Journal of Manufacturing Processes, ISSN 1526-6125, Vol. 39, s. 12-17Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Friction stir welding (FSW) is a reliable joining technology with a wide industrial uptake. However, several fundamentals of the process such as the temperature inside the stirred zone of the weld and its influence on mechanical properties, are not yet fully understood. This paper shows a method for accurate temperature measurements in multiple locations around the tool, to identify the location of the peak temperature, the temperature variations between the advancing and the retreating side of the tool and its relation to the tool geometry. Both standardised thermocouples in the FSW tool and the novel "tool-workpiece thermocouple" method were used to record temperatures.Bead-on-plate welds in 20 mm thickness AA6082-T6 were produced while the temperatures were measured in three locations on the FSW tool: at the shoulder outer diameter, at the transition from shoulder to probe and at the probe tip. It was found that the hottest point in the stirred zone was 607 °C and was located at the transition between the shoulder and probe, on the retreating-trailing side of the tool. The lowest temperature was found at the probe tip on the retreating-leading side of the tool.The results offer a better understanding of the temperature distribution around a FSW tool. The method presented can be applied to verification of thermal simulation models, tool design optimization, quality assurance and temperature feedback control.

  • 16.
    Silva, Ana
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    De Backer, Jeroen
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Bolmsjö, Gunnar
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Analysis of Plunge and Dwell Parameters of Robotic FSW Using TWT Temperature Feedback Control2016Ingår i: Proceedings of 11th International Symposium on Friction Stir Welding, Cambridge, UK, 2016, s. 1-11Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Friction stir welding (FSW) and variants of the process have generated high interest in many industries due to its several advantages such as low distortion, superior mechanical properties over arc welding and the possibility of joining dissimilar materials. Increased complexity of industrial applications require a better control of the welding process in order to guarantee a consistent weld quality. This can be achieved by implementing feedback control based on sensor measurements. Previous studies have demonstrated a direct effect of weld temperature on the mechanical properties of FSW joints, [1], and therefore, temperature is chosen as primary process variable in this study.A new method for temperature measurement in FSW referred to as the Tool-WorkpieceThermocouple (TWT) method has recently been developed by De Backer. The TWT method is based on thermoelectric effect and allows accurate, fast and industrially suitable temperature monitoring during welding, without the need for thermocouples inside the tool [2].This paper presents an application of the TWT method for optimisation of the initial weld phases, plunge and dwell, operation in conventional FSW, which can also be applied to friction stir spot welding (FSSW). An analysis of the operation parameters by using feedback temperature control is presented aiming to better control of the initial weld phases through temperature feedback.

    The introduction of the TWT temperature sensor provides additional process information during welding. Fast data acquisition gives opportunity to differentiate different process phases: contact of probe tip with workpiece surface; plunge phase; dwell phase. This would be followed by tool retraction for FSSW or tool traverse phase for FSW.The effect of the plunge parameters on weld temperature and duration of each phase were studied for the purpose of optimising the process with respect to process (i) robustness, (ii)time, (iii) robot deflection and (iv) quality. By using temperature feedback, it is possible to control the plunge phase to reach a predefined weld temperature, avoiding overheating of the material, which is known to have a detrimental influence on mechanical properties. The work presented in this paper is an important step in the optimization of robotic FSSW and FSW.

  • 17.
    Silva, Ana
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för automationssystem.
    De Backer, Jeroen
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för automationssystem.
    Bolmsjö, Gunnar
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för automationssystem.
    Cooling rate effect on temperature controlled FSW process2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    A continuous trend towards more demanding jointgeometries is imposed across various manufacturingindustries. During Friction Stir Welding (FSW) of suchcomplex geometries, the surrounding environment playsan important role on the final weld quality, especially inthermal aspects. In order to guarantee a consistent weldquality for different conditions, in-process weldingparameter adaptation is needed.This paper studies the effect of the cooling rate onmechanical properties for temperature controlled FSW byusing different backing bar materials. A new temperaturesensor solution, the Tool-Workpiece Thermocouple(TWT) method [1], was applied to measure thetemperature during welding. A FSW-robot equipped withtemperature and force feedback control was used, whererotation speed was varied to maintain a constant weldingtemperature. AA7075-T6 lap joints were performed withand without temperature control. The cooling rate duringwelding was acquired and macrographs and mechanicalproperties were evaluated for each weld. The rotationspeed offered a fast response promoting the heat inputnecessary to weld at the set temperature. Temperaturecontrolled welds presented a better behaviour undertensile loads. The results prove that temperature controlusing the TWT method is suitable to achieve higher jointquality and provides a fast setup of optimal parameters fordifferent environments.The work presented is an important step in the processoptimization through feedback control which willconsider not only the operational parameters of theprocess as such but also the resulting quality of the joint.

  • 18.
    Silva, Ana
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    De Backer, Jeroen
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Bolmsjö, Gunnar
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Temperature measurements during friction stir welding2017Ingår i: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 88, nr 9-12, s. 2899-2908Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The increasing industrial demand for lighter, more complex and multi-material components supports the development of novel joining processes with increased automation and process control. Friction stir welding (FSW) is such a process and has seen a fast development in several industries.This welding technique gives the opportunity of automation and online feedback control, allowing automatic adaptation to environmental and geometrical variations of the component.Weld temperature is related to the weld quality and therefore proposed to be used for feedback control. For this purpose, accurate temperature measurements are required. This paper presents an overview of temperature measurement methods applied to the FSW process. Three methods were evaluated in this work: thermocouples embedded in the tool, thermocouples embedded in the workpiece and the tool-workpiece thermocouple(TWT) method. The results show that TWT is an accurate and fast method suitable for feedback control of FSW.

  • 19.
    Silva, Ana
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för automationssystem.
    De Backer, Jeroen
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för automationssystem.
    Bolmsjö, Gunnar
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för automationssystem.
    TWT method for temperature measurement during FSW process2015Ingår i: The 4th international Conference on scientific and technical advances on friction stir welding & processing, San Sebastian, Spain, 2015, s. 95-98Konferensbidrag (Refereegranskat)
    Abstract [en]

    Friction stir weld (FSW) has generated a high interest in many industry segments in the past 20 years. Along with new industrial challenges, more complex geometries and high quality demands, a better control of the welding process is required. New approaches using temperature controlled welding have been proposed and revealed good results. However, few temperature measurement methods exist which are accurate, fast and industrially suitable. A new and simple sensor solution, the Tool-Workpiece Thermocouple (TWT) method, based on the thermoelectric effect was recently developed.This paper presents a calibration solution for the TWT method where the TWT temperature is compared to calibrated thermocouples inside the tool. The correspondence between both methods is shown. Furthermore, a calibration strategy in different aluminium alloys is proposed, which is based on plunge iterations. This allows accurate temperature monitoring during welding, without the need for thermocouples inside the tool.

  • 20.
    Silva, Ana
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    De Backer, Jeroen
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Bolmsjö, Gunnar
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Welding Temperature during FSW of 5 mm thickness AA6082-T62017Ingår i: 5th international conference on scientific and technical advances on friction stir welding & processing, Metz, France, 11-13 October 2017., 2017Konferensbidrag (Övrigt vetenskapligt)
  • 21.
    Soron, Mikael
    et al.
    ESAB Welding AB .
    De Backer, Jeroen
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för elektro- och automationsteknik.
    Christiansson, Anna-Karin
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för process- och produktutveckling.
    Ilar, Torbjörn
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för industriell produktion.
    A local model for online path corrections in friction stir welding2010Ingår i: INTERNATIONAL CONFERENCE ON SCIENTIFIC AND TECHNICAL ADVANCES ON FRICTION STIR WELDING AND PROCESSING. Program.http://www.polytech-lille.fr/IMG/pdf/program.pdf, 2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    Friction stir welding (FSW) has always been associated with high forces and rigid machines Today’s trends towards joining of more complex structures in e.g. the automotive and aerospace industry, the applications require machinery with increased dexterity and flexibility, which cannot be achieved with the traditional FSW systems. But the introduction of more flexible machines, with more complex workspace capacity, will lead to undesired tool path deviations and in worst case a weld seam with inferior quality. In this study an industrial robot system is used to emphasise the need to compensate for the deviations caused by the high lateral forces resulting from the FSW process. A local model to compensate for such deviations is implemented, evaluated and compared to uncompensate welds in terms of quality and reliability.

1 - 21 av 21
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