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  • 1.
    Abebe Mengistu, Bemnet
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Internal sensor measurement to reduce the need of coordinate measuring machines2017Självständigt arbete på avancerad nivå (magisterexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This thesis presents the approach of determining the machining  errors on a five axis CNC machine using sensors already fitted in the machine to extract valuable data up on process called CITE(CNC Integrity Tracing Equipment) system and measuring the machined workpiece geometry using CMM(Coordinate measurement machine). CITE measurement system is the data acquisition hardware and software system developed by University West for collecting position information from encoders of a machine tool. The collected information could then be used to assess the quality and adjustment of a machine tool, CNC programs and the CNC control parameters. The aim of this study is to examine the roundness and concentricity detection capacity of the CITE system by conducting different milling methods and a turning process. In an example cutting of a workpiece, the CITE measurement system was used for recording the machining process. After that, radial error, centre point deviation and circle roundness errors, analysed using MATLAB based on collected CNC tool movement data. CMM measurement used to verify the results obtained from the CITE measurement system. The investigation conducted on the small circles shows that the CITE measurement system have capability of identifying radial errors in different method of millings (slot, up and down). Centre point deviation and roundness errors measured by the CITE system doesn`t show significant differences between milling methods as seen on CMM measurement.

  • 2.
    Agardsson, Edvin
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för maskinteknik och naturvetenskap.
    Leijer, Malin
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för maskinteknik och naturvetenskap.
    Verktyg för identifiering av tidsåtgång för materialhantering2016Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Autoliv Sverige AB är ett företag som ligger i Vårgårda och tillverkar airbagar, gasgeneratorer samt elektronik till radarsystem. I framtiden finns planer för att expandera produktionen men i dagsläget vet företaget inte hur mycket resurser som går åt för materialflödet till de olika produktionslinorna. För att ta reda på hur mycket personella resurser som behövs både i befintligt materialflöde och i framtida produktionslinor vill företaget undersöka systemet som matar fram material till produktionen. För att ta fram ett verktyg som gör detta används aktionsforskning som huvudmetodik. Aktionsforskning utgör en iterativ process som består av observationer, framtagning av lösningsförslag och utvärdering av lösningsförslag. Observationerna genomfördes i samband med datainsamlingen där Kanbanrundan undersöktes, definierades och mätetal togs fram. Detta för att få en grundförståelse för vad innehållet i verktyget skulle vara.Nästa steg i processen var framtagning av lösningförslag, vilka skapades med hjälp av benchmarking av interna dokument och informationen som samlats från observationerna. En konceptmodell per person skapades och ett koncept valdes sedan ut som utgångspunkt för fortsatt utveckling av verktyget. Modellen blev sedan granskad respektive förbättrad av medlemmarna och handledaren på företaget i en iterativ process.När modellen ansågs klar verifierades det mot verkligheten och den insamlade datan. Verktyget validerades sedan genom att en anställd på Logistikavdelningen fick testa det. Utöver utvecklandet av verktyget och insamlingen av datan utfördes en benchmarking både internt på företaget och externt på ett annat företag för att studera olika materialhanteringsprocesser.I analysen diskuterades för- och nackdelar med olika val och iakttagelser som gjorts, både i arbetssättet för detta examensarbete och dess olika delar men också för materialhanterarens arbetssätt och instruktioner. Resultatet av arbetet blev ett verktyg som uppfyller de krav som formulerades i början av arbetet. Utöver verktyget upptäcktes även ett flertal förbättringsmöjligheter kring materialflödet och produktionen.

  • 3.
    Agic, Adnan
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT). Seco Tools AB,Fagersta, Sweden.
    Gutnichenko, O.
    Division of Production and Materials Engineering, Lund University, Sweden.
    Eynian, Mahdi
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Ståhl, J-E
    Division of Production and Materials Engineering, Lund University, Sweden.
    Influence of cutting edge geometry on force build-up process in intermittent turning2016Ingår i: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 46, s. 364-367Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the intermittent turning and milling processes, during the entry phase the cutting edges are subjected to high impact loads that can give rise to dynamical and strength issues which in general cause tool life reduction. In this study the effect of geometrical features of the cutting tool on the force generation during the entry phase is investigated. Cutting forces are measured by a stiff dynamometer at a high sampling frequency. In addition, the chip load area is analyzed and related to the measured cutting force. The results show that micro-geometrical features, in particular the protection chamfer, significantly affect the force generation during the entry phase.

  • 4.
    Anderberg, Staffan
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för industriell produktion.
    A study of process planning for metal cutting2009Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Process planning as a function for competitiveness is often neglected. However, as an intermediary between product development and manufacturing, it holds a key function in transforming product specifications and requirements into a producible process plan. Demands and requirements should be met concurrently as manufacturing costs and lead times are minimised. The focus of this thesis is the act of process planning, where the use of better methodologies, computer-aids and performance measurements are essential parts. Since process planning has the function of transforming demands and requirements, changing customer and regulative requirements are vital to regard. Since environmentally benign products and production increases in importance, the research presented in this thesis includes a CNC machining cost model, which relates machining costs to energy consumption.  The presented results in this thesis are based on quantitative and qualitative studies in the metal working industry.

     

    This thesis has contributed to an enhanced understanding of process planning to achieve better performance and important areas for improvements. Despite a 50 year history of computerised process planning aids, few of these are used in the industry, where manual process planning activities are more common. Process planning aids should be developed around the process planner so that non-value adding activities, such as information management and documentation are minimised in order to allow more resources for value adding activities, such as decision making. This thesis presents a study of systematic process planning in relation to perceived efficiency. This correlation could however not be verified, which opens up for further studies of other possible explanations for process planning efficiency. Process planning improvements in the industry are difficult to make, since there is little focus on process planning activities and limited knowledge about actual performance hereof. This means that measures taken regarding process planning development are difficult to verify.

  • 5.
    Anderberg, Staffan
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för industriell produktion.
    Beno, Tomas
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för industriell produktion.
    Pejryd, Lars
    Production Technology Centre, Innovatum AB.
    CNC machining process planning productivity – a qualitative survey2009Ingår i: Proceedings of The International 3'rd Swedish Production Symposium, SPS 09, 2009, s. 228-235Konferensbidrag (Refereegranskat)
    Abstract [en]

    Process planning is the link between design and manufacturing and consequently an important function, since it influences many of the company objectives. However, many companies have little knowledge about their process planning function and the efficiency is thus not optimal. The paper focuses on the automation level of process planning as a mean to improve process planning efficiency. Six CNC machining companies was interviewed and accordingly analysed through a five dimensional automation level model to understand their process planning work. The main findings are that the automation level is low and concurrent engineering is lacking in many of the investigated companies.

  • 6.
    Anderberg, Staffan
    et al.
    Högskolan Väst, Institutionen för teknik, matematik och datavetenskap, Avd för maskinteknik.
    Beno, Tomas
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för industriell produktion.
    Pejryd, Lars
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för industriell produktion.
    Production preparation methodology in Swedish metal working industry - a State of the Art investigation2008Ingår i: Swedish Production Symposium, Stockholm 18-20 November 2008. Proceedings: The Swedish Production Academy's annual conference / [ed] Bengt Lindberg och Johan Stahre, Stockholm: The Swedish Production Academy , 2008, s. 443-450Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    This article presents a brief state of the art in the Swedish metal working industry regarding the production preparation process for the machine centre. The article is based on a relationship model from which a questionnaire was developed. The model incorporates the perceived preparation process efficiency, the amount of systematic preparation work, in relation to the companies’ premises as possible causes. The investigation is based on a general hypothesis that a more systematic approach in the preparation process leads to higher preparation process efficiency. This hypothesis was supplemented by two more hypotheses and additional analyses to create an understanding of the situation. The main finding in this investigation is that there appear to be no relationship between increased  ystematic preparation work and perception of higher preparation efficiency. The investigation also indicates that many metal working companies have little knowledge about the performance of their preparation process and that there is an efficiency improvement potential of nearly 30%.

  • 7.
    Anderberg, Staffan
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för industriell produktion.
    Kara, Sami
    University of New South Wales.
    Energy and cost efficiency in CNC machining2009Ingår i: The 7th CIRP Conference on Sustainable Manufacturing: Chennai, India, December 2-4, 2009., 2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    General cost for CNC machining and the associated energy cost are set in the context of making economic and environmental improvements. This creates an incentive for manufacturing companies to investigate the energy efficiency of manufacturing processes. The paper presents a costing model, based on machining experiments. The model is accompanied with an industry based case to estimate the cost savings. The results show that substantial cost savings with respect to energy efficiency is unlikely, since energy costs in CNC machining comprises a small cost component. However significant cost savings can be achieved if the production output is increased as a consequence from higher material removal rates due to optimised machining parameters.

  • 8.
    Anderberg, Staffan
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för industriell produktion.
    Kara, Sami
    University of New South Wales.
    Beno, Tomas
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för industriell produktion.
    Impact of energy efficiency on computernumerically controlled machining2010Ingår i: Proceedings of the Institution of mechanical engineers. Part B, journal of engineering manufacture, ISSN 0954-4054, E-ISSN 2041-2975, Vol. 224, nr B4, s. 531-541Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Increasing environmental demands from governmental bodies and customers stress the importance of companies improving their environmental performance. The research presented here shows that productivity and cost efficiency improvements can be achieved alongside energy savings in a computer numerically controlled machining environment. This improves the profitability of the companies, but also leads them towards more sustainable and environmentally aware manufacturing; the relationship between machining parameters, machining costs, and energy consumption is evaluated. From this perspective, it is important that production planners etc. understand the methodological possibilities for improvements in cost and energy efficiency. The current research is based on a machining cost model and experiments where energy consumption and tool wear were monitored.

  • 9.
    Andersson, Johan
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för industriell produktion.
    Utvärdering och förbättring gällande Volvo Aeros tillämpning av metodiken praktisk problemlösning2012Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Volvo Aero utvecklar, konstruerar, tillverkar och utför underhåll av motorer och tillhörande komponenter för civila och militära flygplan. Visionen är att leverera världsledande transportlösningar genom ständig förbättring och långsiktig utveckling av verksamheten, vilket för det dagliga arbetet innebär systematisk problemlösning genom metodiken praktisk problemlösning, vars ursprung är Toyota.

    Syftet med studien var att undersöka huruvida Volvo Aeros tillämpning av praktisk problemlösning var enkel, systematisk och vägledande, vilket ur Toyotas perspektiv ger förutsättning för effektiv problemlösning.

    Inledningsvis beskrevs Toyotas inställning och beteende till problemlösning utifrån The Toyota Way, som sedan följdes upp med en litteraturstudie gällande praktisk problemlösning. Vidare genomfördes en pilotstudie där Volvo Aeros tillämpning av praktisk problemlösning applicerades på ett organisatoriskt problem. Därefter utvärderades pilotstudien och förbättringsområden identifierades där metodiken var svår, otydlig och otillräckligt vägledande. Slutligen föreslogs följande förbättringar gällande Volvo Aeros tillämpning av praktisk problemlösning, vilka var vetenskapligt förankrade till Toyota.

    • Definiering och analysering av symtomen ger förståelse för problemets orsaker.
    • Kvantifiering av nuvarande tillstånd och det förväntades åskådliggör problemets omfattning.
    • Framgår grundorsaken tydligt är sannolikt motåtgärden uppenbar.
    • En god tillämpning av Plan-Do-Check-Act (PDCA) utgör ett effektivt och kraftfullt maskineri för ständig förbättring.

    Förbättringarna som föreslogs syftade till att förenkla Volvo Aeros metodik och ge användaren ökad trygghet och vägledning, vilket ger förutsättning för effektiv problemlösning som möjliggör daglig tillämpning och främjar ständig förbättring. 

  • 10.
    Bahbou, M. Fouzi
    Högskolan Väst, Institutionen för teknik, matematik och datavetenskap, Avd för maskinteknik.
    A study of the adhesion strength of plasma sprayed coatings2007Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
  • 11.
    Bahbou, M. Fouzi
    et al.
    Högskolan Väst, Institutionen för teknik, matematik och datavetenskap, Avd för maskinteknik.
    Nylén, Per
    Högskolan Väst, Institutionen för teknik, matematik och datavetenskap, Avd för maskinteknik.
    On-Line measurement of plasma-sprayed ni-particles during impact on a ti-surface: influence of surface oxidation2007Ingår i: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 16, nr 6, s. 506-511Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The objective of this study was to analyze the impact of plasma-sprayed Ni5%Al particles on polished and grit-blasted Ti6Al4V samples under oxidized and nonoxidized conditions. For this purpose, measurements of thermal radiation and velocity of individual plasma-sprayed particles were carried out. From the thermal radiation at impact, splat diameter during flattening and temperature evolution during cooling were evaluated. Characteristic parameters related to the quality of contact between the splat and the substrate were retrieved. The flattening speed was introduced to characterize wetting, while the cooling rate was used to characterize solidification. The idea was to get a signature of particle impact for a given surface roughness and oxidation state by identifying parameters which strongly affect the splat behavior. Sieved Ni5%Al powder in a narrow range (+65 −75 μm) was sprayed on four sets of titanium alloy surfaces, consisting of polished and grit-blasted samples, one set had a nonoxidized surface and the other one was oxidized in an oven at 600 °C for two hours. Resulting splats after impact were characterized by scanning electron microscopy, the splats on oxidized surface showed pores in their core and detached fingers at the periphery. The cooling rate and flattening degree significantly increased on the oxidized smooth surface compared to the nonoxidized one. This trend was not found in grit-blasted surfaces, which implies that impact phenomena are different on grit-blasted surfaces than on smooth surfaces thus further work is needed.

  • 12.
    Bahbou, M. Fouzi
    et al.
    Högskolan Väst, Institutionen för teknik, matematik och datavetenskap, Avd för maskinteknik.
    Nylén, Per
    Högskolan Väst, Institutionen för teknik, matematik och datavetenskap, Avd för maskinteknik.
    Relationship between surface topgraphy parameters and adhesion strength for plasma spraying2005Ingår i: ITSC 2005: Thermal Spray connects: Explore its surfacing potential!, The Material Information Society , 2005, s. 1027-1031Konferensbidrag (Refereegranskat)
    Abstract [en]

    To achieve sufficient adhesion strength within thermal spraying, the surface to be coated has to be modified. Grit blasting is the most common way to generate a clean and roughened surface. The bonding mechanism between the grit-blasted substrate and the coating is assumed to be due to mechanical anchoring, why an optimal surface roughness is essential. The surface roughness is usually evaluated using Ra which cannot fully characterize the complex nature of the chaotic substrate topography. This study was performed in order to evaluate if Ra can be replaced by other surface characteristic parameters such us R.q, Rpk, Rpv, Rk…with higher correlation to adhesion strength. Average roughness was measured by a perthometer and with white light interferometry to get 3D images of the surface topography. Disc shaped substrate samples of Ti6Al4V (AMS 4928) were grit blasted with aluminium oxide grit and plasma sprayed with a Ni5%Al coating. Adhesion strength was determined according to the ASTM C633 standard. The correlation between a number of different surface-parameters and adhesion strength were evaluated and compared with Ra.

  • 13.
    Bahbou, M. Fouzi
    et al.
    Högskolan Väst, Institutionen för teknik, matematik och datavetenskap, Avd för maskinteknik.
    Nylén, Per
    Högskolan Väst, Institutionen för teknik, matematik och datavetenskap, Avd för maskinteknik.
    Two-step grit blasting for enhanced adhesion of thermal spray coatings2004Ingår i: Surface modification technologies XVIII: proceedings of the eighteenth international conference on surface modification technologies held in Dijon, France November 15-17, 2004, 2004, s. 23-27Konferensbidrag (Refereegranskat)
  • 14.
    Bahbou, M. Fouzi
    et al.
    Högskolan Väst, Institutionen för teknik, matematik och datavetenskap, Avd för maskinteknik.
    Nylén, Per
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för industriell produktion.
    Barbezat, G.
    Sulzer Metco, Wohlen, Switzerland .
    A parameter study of the Protal® Process to optimise the adhesion of Ni5Al Coatings2004Ingår i: Thermal Spray 2004 : Advances in technology and applications: Proceedings of the International Thermal Spray Conference 10-12 May 2004, Osaka, Japan Thermal Spray 2004, 2004, s. 898-902Konferensbidrag (Refereegranskat)
    Abstract [en]

    The Protal process combines surface preparation using a laser and thermal spraying in one production step. The laser preparation is based on a photomechanical reaction induced by the interaction between a laser of high instantaneous power and a polluted surface. The mechanism of bonding and the coating-substrate interface are then changed in comparison with grit blasting resulting in a significantly reduced substrate roughness. This study is aimed at finding the optimal Protal process parameters for the coating adhesion of a Ni5%Al sprayed on Ti6Al4V and IN718 alloys. The parameters investigated are laser beam intensity, the time delay between the laser impact and the spray impact, powder feed rate, substrate roughness and temperature. A test plan including these parameters is analysed by means of a fractional factorial design of experiment method. The adhesions of the coatings are measured using the ASTM C633 standard test. Data are analysed by a multiple linear regression model using a least squares fit. In addition, the coating/substrate interface is examined by optical and electron scanning microscopy (SEM) techniques as well as by Auger electron spectroscopy. Substrate roughness, substrate temperature and laser intensity are all shown to have a negative correlation with adhesion strength within the investigated range. Areas of diffusion are noticed at the coating/substrate interface.

  • 15.
    Bahbou, M. Fouzi
    et al.
    Högskolan Väst, Institutionen för teknik, matematik och datavetenskap, Avd för maskinteknik.
    Nylén, Per
    Högskolan Väst, Institutionen för teknik, matematik och datavetenskap, Avd för maskinteknik.
    Wigren, J.
    Volvo Aero, Trollhättan.
    Effect of grit blasting and spraying angle on the adhesion strength of a plasma-sprayed coating2004Ingår i: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 13, nr 4, s. 508-514Artikel i tidskrift (Refereegranskat)
  • 16.
    Beno, Tomas
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för industriell produktion.
    Anderberg, Staffan
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för process- och produktutveckling.
    Green machining: improving the bottom line2009Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The aim of this paper is to present how Green machining can be established in the metal working industry for taking immediate actions towards a more environmental friendly manufacturing, but also to address areas for research in order to advance towards a more sustainable manufacturing industry. An often overlooked approach is to use the knowledge about the specific cutting energy and its dependency upon machining parameters in order to establish a machining strategy that leads towards a more energy efficient production, but also contributes to increased productivity and thereby improving the bottom line as well. The paper has a production preparation perspective and thus presents the areas where a green machining strategy is applicable.

  • 17.
    Beno, Tomas
    et al.
    Högskolan Väst, Institutionen för teknik, matematik och datavetenskap, Avd för maskinteknik.
    Isaksson, Marina
    Högskolan Väst, Institutionen för teknik, matematik och datavetenskap, Avd för maskinteknik.
    Pejryd, Lars
    Högskolan Väst, Institutionen för teknik, matematik och datavetenskap, Avd för maskinteknik.
    Investigation of Minimal Quantity Lubrication in Turning of Waspalloy2007Ingår i: Advances in Life Cycle Engineering for Sustainable Manufacturing Businesses: Proceedings of the 14th CIRP Conference on Life Cycle Engineering, Waseda University, Tokyo, Japan, June 11th-13th, 2007, Springer , 2007, s. 305-310Konferensbidrag (Refereegranskat)
  • 18.
    Beno, Tomas
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för industriell produktion.
    Isaksson, Marina
    Pejryd, Lars
    Högskolan Väst, Institutionen för ingenjörsvetenskap.
    Machining aerospace material with sub-cooled minimal quantity cppling lubrication fluids2009Ingår i: World Tribology Congress 2009: Kyoto, Japan, September 6-11, 2009Konferensbidrag (Övrigt vetenskapligt)
  • 19.
    Beno, Tomas
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för tillverkningsprocesser. Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Repo, Jari
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för maskinteknik och naturvetenskap.
    Pejryd, Lars
    Örebro Universitet.
    The Use of Machine Tool Internal Encoders as Sensors in a Process Monitoring System2013Ingår i: International Journal of Automation Technology, ISSN 1881-7629, E-ISSN 1883-8022, Vol. 7, nr 4, s. 410-417Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Tool wear in machining changes the geometry of the cutting edges, which affects the direction and amplitudes of the cutting force components and the dynamics in the machining process. These changes in the forces and dynamics are picked up by the internal encoders and thus can be used for monitoring of changes in process conditions. This paper presents an approach for the monitoring of a multi-tooth milling process. The method is based on the direct measurement of the output from the position encoders available in the machine tool and the application of advanced signal analysis methods.

    The paper investigates repeatability of the developed method and discusses how to implement this in a process monitoring and control system. The results of this work show that various signal features which are correlated with tool wear can be extracted from the first few oscillating components, representing the low-frequency components, of the machine axes velocity signatures. The responses from the position encoders exhibit good repeatability, especially short term repeatability while the long-term repeatability is more unreliable.

  • 20.
    Bergström, Per
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Luleå, Sweden.
    Fergusson, Michael
    Xtura AB, Kungsbacka, Sweden.
    Folkesson, Patrik
    Xtura AB, Kungsbacka, Sweden.
    Runnemalm, Anna
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Ottosson, Mattias
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Andersson, Alf
    Chalmers University of Technology, Department of Product and Production Development, Gothenburg, Sweden.
    Sjödahl, Mikael
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Luleå, Sweden.
    Automatic in-line inspection of shape based on photogrammetry2016Ingår i: The 7th International Swedish Production Symposium, SPS16, Conference Proceedings: 25th – 27th of October 2016, Lund: Swedish Production Academy , 2016, s. 1-9Konferensbidrag (Refereegranskat)
    Abstract [en]

    We are describing a fully automatic in-line shape inspection system for controlling the shape of moving objects on a conveyor belt. The shapes of the objects are measured using a full-field optical shape measurement method based on photogrammetry. The photogrammetry system consists of four cameras, a flash, and a triggering device. When an object to be measured arrives at a given position relative to the system, the flash and cameras are synchronously triggered to capture images of the moving object.From the captured images a point-cloud representing the measured shape is created. The point-cloud is then aligned to a CAD-model, which defines the nominal shape of the measured object, using a best-fit method and a feature-based alignment method. Deviations between the point-cloud and the CAD-model are computed giving the output of the inspection process. The computational time to create a point-cloud from the captured images is about 30 seconds and the computational time for the comparison with the CAD-model is about ten milliseconds. We report on recent progress with the shape inspection system.

  • 21.
    Bhoje, Sourabh
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW).
    Termisk cykling provuppställning konstruktion och provning av TBCs för dieselmotorapplikation2017Självständigt arbete på avancerad nivå (magisterexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Thermal barrier coatings (TBCs) thermally insulate the substrate from high temperature exposure. This work attempted to simulate real engine thermal cyclic conditions by designing a test method to evaluate the thermal cyclic fatigue (TCF) performance of different coatings applied inside exhaust manifold of a diesel engine. The coatings investigated in this work comprised of two plasmas-sprayed TBCs (conventional 8YSZ and nanostructured 8YSZ) and one bond coat (NiCoCrAlY). Additionally, these coatings were exposed to isothermal testing and their oxidation behavior was evaluated.   All the coatings along with only substrate were exposed to temperature around 525°C for 150 cycles in thermal cyclic testing carried out on Scania’s heavy-duty diesel engine. For isothermal testing, all coatings along with only substrate material were exposed to 650°C and 750°C for 168 hours respectively. Microstructural analysis by SEM/EDS was carried out to compare the microstructural evolution of the tested coatings with the as sprayed TBCs. In the case of thermal cyclic test, all coatings showed no failure and no TGO growth up to 150 cycles. In the EDS analysis for isothermally tested coatings, oxidation of the substrate at bond coat- substrate interface instead of TGO growth was observed. Bond coat showed lowest oxide layer thickness at 650°C and 750°C followed by conventional YSZ and then nanostructured YSZ. But, conventional YSZ showed microcracks in top coat near top coat- bond coat interface after isothermal testing. Thermal cyclic and isothermal exposure test results showed that bond coated substrate and nanostructured YSZ have the potential to be implemented inside the real manifold.   

  • 22.
    Bolmsjö, Gunnar
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för automationssystem.
    Supporting Tools for Operator in Robot Collaborative Mode2015Ingår i: Procedia Manufacturing, E-ISSN 2351-9789, Vol. 3, s. 409-416Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Making use of robot automation for customized products put high demand not only on the robot but on the efficiency, simplicity and flexibility to actually deploy and use robots in manufacturing stations and production lines in short batches and low volume production. Hence, market oriented product development and production requires more products to be developed and offered in less time than before, and produced for the market with more customizable options. The role of the operator is in this context an important factor and tools are needed to support the operator for highly efficient and flexible production. In this paper, the development and study of supporting tools for operators is presented. A demonstrator has been built for robotic nailing, screwing and manipulation operation in producing scaled down gable wall elements in wood for a family house. Issues raised to support the operator included automatic programming and generating relevant information for the operator for the deployment procedure to prepare for production. During production, different concepts of safety system to support collaboration mode between the operator and the robot was developed and studied. Wearable devices was used for the operator to access the information generated and different safety configurations were developed and evaluated. The baseline for this work has been to identify industrial use cases which has a clear need for automation as well as collaboration between operator(s) and robot(s). Work scenarios were discussed and analyzed with industrial partners and it was concluded that, in addition to the deployment tools, a smart safety system which is able to detect and react on humans entering the robot system work area is needed. This should support for efficient production and less downtime for both automatic mode and collaboration mode. The benefit of operator – robot collaboration is clearly shown as well as the need for supporting tools.

  • 23.
    Bolmsjö, Gunnar
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Bennulf, Mattias
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Zhang, Xiaoxiao
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Safety System for Industrial Robots to Support Collaboration2016Ingår i: Advances in Ergonomics of Manufacturing: Managing the Enterprise of the Future. Proceedings of the AHFE 2016 International Conference on Human Aspects of Advanced Manufacturing, July 27-31, 2016, Walt Disney World®, Florida, USA / [ed] Christopher Schlick, Stefan Trzcieliński, Springer International Publishing , 2016, s. 253-265Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    The ongoing trend towards manufacturing of customized products generates an increased demand on highly efficient work methods to manage product variants through flexible automation. Adopting robots for automation is not always feasible in low batch production. However, the combination of humans together with robots performing tasks in collaboration provides a complementary mix of skill and creativity of humans, and precision and strength of robots which support flexible production in small series down to one-off production. Through this, collaboration can be used with implications on reconfiguration and production. In this paper, the focus and study is on designing safety for efficient collaboration operator—robot in selected work task scenarios. The recently published ISO/TS 15066:2016 describing collaboration between operator and robot is in this context an important document for development and implementation of robotic systems designed for collaboration between operator and robot.

  • 24.
    Bonilla Hernández, Ana Esther
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW).
    Analysis and direct optimization of cutting tool utilization in CAM2015Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The search for increased productivity and cost reduction in machining can be interpreted as the desire to increase the material removal rate, MRR, and maximize the cutting tool utilization. The CNC process is complex and involves numerous limitations and parameters, ranging from tolerances to machinability. A well-managed preparation process creates the foundations for achieving a reduction in manufacturing errors and machining time. Along the preparation process of the NC-program, two different studies have been conducted and are presented in this thesis. One study examined the CAM programming preparation process from the Lean perspective. The other study includes an evaluation of how the cutting tools are used in terms of MRR and tool utilization.

    The material removal rate is defined as the product of three variables, namely the cutting speed, the feed and the depth of cut, which all constitute the cutting data. Tool life is the amount of time that a cutting tool can be used and is mainly dependent on the same variables. Two different combinations of cutting data might provide the same MRR, however the tool life will be different. Thereby the difficulty is to select the cutting data to maximize both MRR and cutting tool utilization. A model for the analysis and efficient selection of cutting data for maximal MRR and maximal tool utilization has been developed and is presented. The presented model shortens the time dedicated to the optimized cutting data selection and the needed iterations along the program development.

  • 25.
    Bonilla Hernández, Ana Esther
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW). GKN Aerospace Engine Systems AB, Flygmotorvagen 1, Trollhattan, 46138, Sweden.
    Lu, Tao
    University of Kentucky, Institute for Sustainable Manufacturing (ISM), Lexington, KY 40506, United States.
    Beno, Tomas
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Fredriksson, Claes
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Jawahir, I. S.
    University of Kentucky, Institute for Sustainable Manufacturing (ISM), Lexington, KY 40506, United States.
    Process sustainability evaluation for manufacturing of a component with the 6R application2019Ingår i: Procedia Manufacturing, E-ISSN 2351-9789, Vol. 33, s. 546-553Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Sustainability in manufacturing can be evaluated at product, process and system levels. The 6R methodology for sustainability enhancement in manufacturing processes includes: reduced use of materials, energy, water and other resources; reusing of products/components; recovery and recycling of materials/components; remanufacturing of products; and redesigning of products to utilize recovered materials/resources. Although manufacturing processes can be evaluated by their productivity, quality and cost, process sustainability assessment makes it a complete evaluation. This paper presents a 6R-based evaluation method for sustainable manufacturing in terms of specific metrics within six major metrics clusters: environmental impact, energy consumption, waste management, cost, resource utilization and society/personnel health/operational safety. Manufacturing processes such as casting, welding, turning, milling, drilling, grinding, etc., can be evaluated using this methodology. A case study for machining processes is presented as an example based on the proposed metrics. © 2019 The Authors. Published by Elsevier B.V.

  • 26.
    Broberg, Patrik
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för maskinteknik.
    Surface crack detection in welds using thermography2013Ingår i: NDT & E international, ISSN 0963-8695, E-ISSN 1879-1174, Vol. 57, s. 69-73Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Thermography is today used within non-destructive testing for detecting several different types of defects. The possibility for using thermography for detecting surface cracks in welded metal plates has here been investigated. During testing the weld is illuminated using a high power infrared light source. Due to surface cracks acting like black bodies, they will absorb more energy than the surrounding metal and can be identified as a warmer area when imaged using an infrared camera. Notches as well as real longitudinal cold cracks in a weld are investigated using the presented method. The results show that thermography is promising as a method for detection cracks open to the surface.

  • 27.
    Broberg, Patrik
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Runnemalm, Anna
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Analysis algorithm for surface crack detection by thermography with UV light excitation2016Ingår i: Quantitative InfraRed Thermography 2016: Abstracts / [ed] Kaczmarek, M. & Bujnowski, A., Gdańsk, Poland: Publishing Gdańsk University of Technology , 2016, s. 144-149Konferensbidrag (Refereegranskat)
    Abstract [en]

    Surface crack defects can be detected by IR thermograpgy due to the high absorption of energy within the crack cavity. It is often difficult to detect the defect in the raw data, since the signal easily drowns in the background. It is therefore important to have good analysis algorithms that can reduce the background and enhance the defect. Here an analysis algorithm is presented which significantly increases the signal to noise ratio of the defects and reduces the image sequence from the camera to one image.

  • 28.
    Broberg, Patrik
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för process- och produktutveckling.
    Sjödahl, Mikael
    Högskolan Väst, Institutionen för ingenjörsvetenskap.
    Runnemalm, Anna
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för process- och produktutveckling.
    Comparison of NDT-methods for automatic inspection of weld defects2015Ingår i: International journal of materials & product technology, ISSN 0268-1900, E-ISSN 1741-5209, Vol. 50, nr 1, s. 1-21Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The purpose of this study is to investigate different NDT-methods for weld inspection in an objective manner. Test objects are produced with known variation of flaws: internal pores, surface and internal cracks, toe radius and weld depth. The NDT-methods compared are: phased array ultrasound, radiography, eddy current, thermography and shearography. The results show that radiography is the better method for volumetric defects in thin plates while ultrasound is better for flat defects and thicker, non-flat plates. Thermography was shown to have a good ability of detecting surface defects. A combination of ultrasound and thermography results in a detection of all the non-geometrical defects investigated in this study.

  • 29.
    Christensen, Tommy
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för industriell produktion.
    Lean Automation på Saab Automobile AB: ett hållbart och flexibelt produktionskoncept2011Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Ett nytt produktionskoncept på Saab Automobile AB – Lean Automation – är under implementering och utveckling. Inriktningen är att utveckla automationslösningar som stödjer principer och arbetsätt inom Lean Produktion. En gemensam nämnare är automation som byggs upp av enkel, standardiserad och modulariserad utrustning och som kan omkonfigureras av egen personal.

    Två pilotinstallationer har gjorts under 2010: Transport med enkel AGV (Lean AGV) samt Lean Automation Robot Cell (LARC). Dessa komponenter ingår i denna studie som inriktar sig på förändringar i det totala produktionssystemet med sikte på en konstant hög produktivitetsnivå även vid frekventa förändringar i volym och produktinnehåll.

    Studien pekar på vikten av att samla produktionspersonalen för att underlätta balansering, men även för att skapa en visuell process där fel snabbt kan upptäckas och åtgärdas. En effektiv balansering av robotar kräver en något annorlunda inriktning där fokus istället ligger på att distribuera arbetselementen på ett lämpligt sätt samt att utnyttja de sammanlagringseffekter som ett gemensamt flöde ger.

    Ett verktyg för att mer ändamålsenligt balansera det värdeskapande arbetet introduceras. Verktyget är avsett för såväl manuellt som robotiserat arbete

    En flödesorienterad metod att knyta samman delsammanbyggnader med huvudflöde presenteras. Metoden bygger på att ersätta gaffeltruckar och manuellt laddade magasin med ett enkelt AGV-flöde. Systemet förmedlar information om produktionsläget till personalen genom att lastbärarna utgör visuella "Kanban-kort". Genom detta visuella system, samt genom att lagkonceptet utnyttjas till att upprätthålla en billig och ändamålsenlig buffert, förebyggs materialbrister.

    Generella riktlinjer för konceptval av interna materialflöden presenteras och exemplifieras. Slutligen beskrivs hur flexibilitetslösningarna kan anpassas till nivån i förädlingskedjan och hur detta är kopplat till ett parallellt respektive seriellt flöde.

  • 30.
    Clement, C.
    et al.
    National School of Engineers, University of Limoges, Limoges, 87280, France.
    Sadeghimeresht, Esmaeil
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för tillverkningsprocesser.
    Lyphout, Christophe
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för tillverkningsprocesser.
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för tillverkningsprocesser.
    Nylén, Per
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för industriell produktion.
    Corrosion behavior of HVAF- and HVOF-sprayed high-chromium Fe-based coatings2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    Fe-based coatings with three particular elemental compositions and two different powder particle size were prepared by high-velocity air fuel (HVAF) and high-velocity oxy fuel (HVOF) techniques. The corrosion behavior of which were comparatively studied in 3.5 wt.% NaCl solution. The results indicated that the coatings produced by HVAF process exhibited denser structure with lower porosity. Polarization and electrochemical impedance spectroscopy (EIS) tests indicated that the HVAF coatings provided better corrosion resistance than the HVOF coatings. The presence of defects was significant in HVOF coatings. The investigation illustrated that the corrosion paths initiated and grow through defects of the coating. Furthermore, adding Cr strongly improved the corrosion resistance of the coatings. The results confirmed that the cheap HVAF process could be a potential alternative to HVOF to fabricate Fe-based coatings for industrial applications.

  • 31.
    Coll Ferrari, Maria Teresa
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för tillverkningsprocesser.
    Forsberg, Amanda
    Uddeholms AB.
    Andersson, Jörgen
    The Swedish School of Mining and Metallurgy.
    Mikula, Pavol
    Nuclear Physics Institute ASCR.
    Beran, Premysl
    Nuclear Physics Institute ASCR.
    Effect of Austenitising Temperature and Cooling Rate on Microstructure in a Hot-Work Tool Steel2014Ingår i: Proceedings of the 6th International Swedish Production Symposium / [ed] Stahre, Johan, Johansson, Björn & Björkman, Mats, 2014, s. 1-7Konferensbidrag (Refereegranskat)
    Abstract [en]

    The effects on microstructucture of austenitising temperature and cooling rate during hardening were studied for a hot-work tool steel. Transformation temperatures were determined by dilatometry, scanning electron microscopy was used to characterise the microstructure and both retained austenite contents and their lattice parameters were measured by neutron diffraction. For lower cooling rates, lower austenitising temperatures produce larger amounts of both retained austenite and bainite. Retained austenite in bainitic structures is higher in carbon than in martensitic structures. Consequently, lowering the austenitising temperature will affect microstructure and properties.

  • 32.
    Dalaei, K.
    et al.
    Chalmers University of Technology, Department of Materials and Manufacturing Technology.
    Karlsson, B.
    Chalmers University of Technology, Department of Materials and Manufacturing Technology.
    Svensson, L. E.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för industriell produktion.
    Stability of shot peening induced residual stresses and their influence on fatigue lifetime2011Ingår i: Materials Science and Engineering A, Vol. 528, nr 3, s. 1008-1015Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mechanical surface treatment methods such as shot peening may improve the fatigue strength of materials. In this study, the effect of shot peening on strain controlled constant amplitude fatigue loading of a near pearlitic microalloyed steel was investigated. The stress amplitudes throughout the whole lifetime were followed, in addition to detailed recording of stress-strain hysteresis loops, particularly at small cycle numbers. The detailed relaxation of residual stresses and the changes in full width of half maximum (FWHM) of the X-ray peak at the surface and in depth as function of the number of cycles and plastic strain were recorded. By these techniques, the onset as well as the rate of relaxation of residual stresses could be followed at different strain amplitudes. Pronounced increase in lifetime of the shot peened specimens tested at total strain amplitude smaller than 0.3% (corresponding to 0.034% plastic strain amplitude) was achieved. This coincides with reasonably stable residual stresses at the surface and in depth. © 2010 Elsevier B.V.

  • 33.
    Danielsson, Fredrik
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för elektro- och automationsteknik.
    Svensson, Bo
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för elektro- och automationsteknik.
    A flexible lean automation concept for robotized manufacturing industry2011Ingår i: Proceedings of the 4th International Swedish Production Symposium: 3 - 5, May, Lund, Lund: Swedish Production Academy , 2011, s. 361-367Konferensbidrag (Refereegranskat)
    Abstract [en]

    Due to constant changesin the market there is a need for low-cost and low-volume manufacturing.Usually this type of production is difficult to automate due to the time ittakes to become profitable and the inflexibility of such solutions.  Therefore, flexible automation solutions needto be addressed together with cost effective aspects. In this paper, a newconcept for the design of a flexible, robotized solution based on leanautomation is presented and simulated. The proposed lean automation concept isformed of standardized robot stations, human-robot collaboration and costeffective level of automation. The main goals are flexible automated productionsystem and reduced production cost. This paper shows that the proposed flexiblelean automation concept has some key advantages compared to the traditionalrobot cells; a longer lifetime for the robot cell as well as being easier tore-balance, introduce new parts to and expand the cell. Further, it also showsthat the proposed concept reduces the cost for automation of products with low volume.

  • 34.
    Danielsson, Fredrik
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för elektro- och automationsteknik.
    Svensson, Bo
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för elektro- och automationsteknik.
    Gustavsson, Steve
    Högskolan Väst.
    A Flexible Lean Automation Concept for Robotized Manufacturing Industry2010Ingår i: MESM 2010: 11th Middle Eastern Simulation Multiconference / [ed] Mar wan Al-Akai di, Ostend: Eurosis , 2010, s. 101-104Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper describes a general virtual manufacturing concept for industrial control systems. Our virtual manufacturing concept provides a distinct advantage; programming, verification and optimisation of complex real-time dependent control functions described by real control code, which can be directly transferred to the real manufacturing system. To achieve this distinct advantage, a time synchronised virtual manufacturing system is a necessity. The aim of this paper is thus to present and to describe in detail, our proposed virtual manufacturing concept. To the authors’ knowledge no such general virtual manufacturing concept, i.e. one that can correctly handle complex real-time dependent control functions, currently exists. To summarise previous work related to virtual manufacturing and industrial control systems, several critical issues have been identified. The virtual manufacturing concept proposed in this paper addresses these issues. To verify that our concept can manage these critical issues found and further is suitable in industrial applications a virtual manufacturing test case is also presented. The test case, that includes motion control (i.e. servo), complex control functions, real control systems etc., was carried out with success.

  • 35.
    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.

  • 36.
    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.

  • 37.
    De Backer, Jeroen
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för industriell produktion.
    Verheyden, Bert
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för industriell produktion.
    Robotic Friction Stir Welding for Automotive and Aviation Applications2010Självständigt arbete på avancerad nivå (magisterexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Friction Stir Welding (FSW) is a new technology which joins materials by using frictional heat. Inthe first part of this thesis, a profound literature study is performed. The basic principles, therobotic implementation and possibilities to use FSW for high strength titanium alloys areexamined. In the next phase, a FSW-tool is modelled and implemented on an industrial robot in arobot simulation program. Reachability tests are carried out on car body parts and jet engineparts. By using a simulation program with embedded collision detection, all possible weldinglocations are determined on the provided parts. Adaptations like a longer FSW-tool and amodified design are suggested in order to get a better reachability. In different case studies, thenumber of required robots and the reduction of weight and time are investigated and comparedto the current spot welding process.

  • 38.
    Edstorp, Marcus
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för industriell produktion.
    Weld Pool Simulations2008Licentiatavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    This investigation is devoted to the study of welding and its effect on the workpiece, focusing on the thermo and fluid dynamical phenomena occuring during a autogenous or nonautogenous arc fusion welding process. Its aim is to simulate the behaviour of the weld pool and analyze the consequence of the solid-liquid phase change, thus obtaining a methodology for predicting the appearance of weld defects related to solidification and cooling. In order to accomplish this, we solve equations governing a number of continuum mechanical and electromagnetical quantities, as well as consider the motion of the freely moving boundary of the weld pool. Since the state of these quantities is strongly influenced by phenomena such as arc and droplet impingement, non-isothermal phase change, surface tension, Marangoni forces and Lorentz forces, much effort is necessarily devoted to the modelling of the corresponding fluxes and sources, as well as to the implementation of computationally efficient techniques for simulating the geometrical deformation of the workpiece, which in our setting is entirely determined by the motion of the weld pool surface.

    Common to all arc fusion welding processes is the employment of a welding arc. Many techniques rely on the arc to clean and shield the workpiece during the process, however in this study we consider it to be its main purpose to cause the local increase of thermal energy that is required for the establishment of the weld pool, and also to exert the mechanical forces that provoke the subsequent fluid flow which enhances heat transfer and facilitates weld penetration. The physics of the welding arc itself is quite intricate, and although the modelling of the arc is not the prime objective of this research project, we conclude that arc forces act on the pool surface, and that the investigation of the arc behaviour is important insofar that it provides input to the pool model and thus enables a more accurate prediction of the quality of the weldment that is created once the pool has solidified

  • 39.
    Ellers, Fredrik
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för automationssystem.
    Knutsson, Stefan
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för automationssystem.
    Utveckling, konstruktion och CE-märkning av robotcell för utbildningssyfte2014Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Detta examensarbete har handlat om arbetet med att CE-märka en egenutvecklad robotcell som skall användas i utbildningssyfte. En betydande del av arbetet har varit att samla in nödvändig information gällande CE-märkning, robotsäkerhet och riskbedömning. Säkerhetsåtgärderna som vidtogs för att uppnå kraven som ställs sett från standarder och med de förutsättningar, gällande den begränsadeytan samt miljön robotcellen skall användas i. Arbetet har lett fram till att en stor mängd teknisk dokumentation är framtagen. Denna skall ligga till grund för den slutliga CE-märkningen av robotcellen. CE-märkningen är inte slutförd då robotcellen ej är färdigställd än och det leder till att CE-märkningen inte kan slutföras då slutgiltiga kontroller måste genomföras efter färdigställande av robotcellen beträffande konstruktion och säkerhet

  • 40.
    Emanuelsson, Viktor
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Wahlberg, Christoffer
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Omkonstruktion av fixtur avsedd för manuell svetskontroll av turbinmotorstativ2016Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Examensarbetet behandlar framtagning av en fixtur för manuell fysisk och okulär svetskontroll av det bakre turbinstativet 30k TEC (Turbine Exhaust Case) för GKN Aerospace i Trollhättan. Huvudproblemet bestod i att inspektion av 30k TEC inte tidigare skett i den omfattning vilken är aktuell idag. Syftet var att underlätta inspektionspersonalens arbetssituation. Arbetet baseras på, för examensarbetet, relevanta metoder vilka inkluderar datainsamling, tolkning av insamlad data, konceptgenerering och konceptval. Berörda parter identifierades samt dess respektive krav på fixtur och miljö. Tillsammans med intervjuer och ob¬servationer av liknande fixturer genererades konceptförslag. Konceptförslagen gick sedan igenom en konceptvalsprocess vilket resulterade i ett slutgiltigt koncept. Det slutgiltiga konceptet tillåter motordriven rotation av motorstativet samt är utrustat med vältskydd. Vältskyddet hindrar turbinstativet från att välta under inspektion vilket kan resultera i såväl materiella skador på detalj och utrustning som fysiska skador på inspektions¬personal. Då det är möjligt att rotera motorfästet med motordrift klassas fix-turen som en maskin och skall därför CE-märkas av tillverkaren. Arbetet inkluderar därför fördjupad kunskap inom maskindirektiv och krav gällande CE-märkning av maskiner. För att tillgodose ergonomiska aspekter för inspektionspersonal studerades riktlinjer för ergo¬nomiskt arbete.Rapporten presenterar slutgiltigt koncept med dess ingående delar. Arbetets leverabler till arbetsgivaren består av beställningsunderlag färdigt att skickas till tillverkaren av fixturen innehållande ritningar samt komponentlistor. Såväl tillverkare som inspektionspersonal har visat en positiv inställning till resultatet.

  • 41.
    Eriksson, Kristina. M.
    Högskolan Väst, Institutionen för teknik, matematik och datavetenskap, Avd för maskinteknik.
    A comparison of changeover time reduction through design changes and changeover sensitive heuristics2007Ingår i: PLANs forsknings- och tillämpningskonferens 2007: kundfokuserade varor och tjänster : artiklar från konferensen på Tekniska högskolan i Jönköping 5-6 september 2007, PLAN - Logistikföreningen , 2007, s. 51-66Konferensbidrag (Refereegranskat)
  • 42.
    Eriksson, Kristina M
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för industriell produktion.
    Hanson, R.
    Chalmers University of Technology.
    Performance impact of options for routing and delivery initiation in tugger train delivery systems2008Ingår i: Proceedings of SPS08, Swedish Production Symposium, 18th – 20th November 2008, Stockholm, Sweden, 2008Konferensbidrag (Övrigt vetenskapligt)
  • 43.
    Eynian, Mahdi
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för tillverkningsprocesser.
    Analytical Stability Prediction in Five Axis Ball-End Milling2013Ingår i: Proceedings of the International Conference on Advanced Manufacturing Engineering and Technologies NEWTECH 2013 / [ed] Andreas Archenti and Antonio Maffei, Stockholm: KTH Royal Institute of Technology, 2013, s. 189-198Konferensbidrag (Refereegranskat)
    Abstract [en]

    In five axis ball-end milling, the cutting edge is a continuous curve and the engagement with workpiece changes as the cutting tool rotates. Therefore the sensitivity to vibration varies along the cutting edge and as the tool rotates. In this paper, the vibration-force relationship (VFR) is obtained for infinitesimal length of cutting edge as a function of tool’s rotation angle. Numerical integration results in the VFR of the whole cutting edge and the tool. VFR of the tool is coupled to the dynamic vibration model of the tool and the workpiece to predict the possibility of vibrational instability. This algorithm is then used to predict the effects of changing the lead angle in a test setup with a flexible depth of cut direction. The analytical results, along with experiments demonstrate that the large lead angles considerably improve the stability of the process.

  • 44.
    Eynian, Mahdi
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för tillverkningsprocesser.
    Effect of thin viscoelastic material treatments of the clamping region on dynamic stiffness of the cantilever beams2013Ingår i: Proceedings of the International Conference on Advanced Manufacturing Engineering and Technologies NEWTECH 2013: Volume 1 / [ed] Andreas Archenti and Antonio Maffei, Stockholm: KTH Royal Institute of Technology, 2013, s. 313-322Konferensbidrag (Refereegranskat)
    Abstract [en]

    Cantilever beams and similar structures are found in machining systems. Often a set of cantilever beams attached to each other on spindle-tool holder and tool holder-cutter interfaces position the cutting edge with respect to the workpiece. Small static stiffness leads to deformations and geometrical errors due to the process forces, while small dynamic stiffness initiates chatter vibrations. Dynamic stiffness of structures could be improved by passive or active damping methods. Passive damping methods are suitable design choices considering their low cost and ease of application. In this paper, the constrained layer damping (CLD) method is compared to the application of viscoelastic damper materials on the clamping region and the resulting improvements are compared in terms of enhancement of damping ratio and dynamic stiffness. The maximum enhancement of dynamic stiffness was 487% using a thick layer of viscoelastic material on the clamping region. The effect of the thickness of the viscoelastic material is also studied which shows a linear increase in dynamic stiffness as the thickness of the viscoelastic layer increases.

  • 45.
    Eynian, Mahdi
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Selection of chatter-free milling conditions using vibration frequency measurements2016Ingår i: The 7th International Swedish Production Symposium, SPS16, Conference Proceedings: 25th – 27th of October 2016, Lund: Swedish Production Academy , 2016, s. 1-6Konferensbidrag (Refereegranskat)
    Abstract [en]

    Unwanted vibration of the tool with respect to the workpiece, known as chatter, can damage machine tool, cutting tool, and the surface finish of the workpiece in a machining operation such a milling. These vibrations could be avoided by reducing the depth of cut, but this approach hurts the productivity and reduces material removal rate. Previous studies have established methods, known as stability prediction methods that provide that enable using large depth of cuts while avoiding chatter. The calculation of stability lobes commonly starts by measurement of dynamic properties of the machining structure. This paper investigates an alternative approach, in which vibration frequencies gathered during test cuts with the target machining system are used to identifying the modal parameters of the machining system in its operational condition. An earlier method that was based on a one dimensional dynamics model is modified to use relationships developed for a two dimensional model that describes the dynamics of spindles and tools with axisymmetric dynamics. This approach improves the stability lobe prediction considerably as shown in results.

  • 46.
    Fahlström, Karl
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW).
    Laser welding of boron steels for light-weight vehicle applications2015Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Laser beam welding has gained a significant interest during the last two decades. The suitability of the process for high volume production has the possibility to give a strong advantage compared to several other welding methods. However, it is important to have the process in full control since various quality issues may otherwise occur. During laser welding of boron steels quality issues such as imperfections, changes in local and global geometry as well as strength reduction can occur. The aspects that need to be considered are strongly depending on alloy content, process parameters etc. These problems that can occur could be fatal for the construction and the lowest level of occurrence is wanted, independent of industry.

    The focus of this study has been to investigate the properties of laser welded boron steel. The study includes laser welding of boron alloyed steels with strengths of 1500 MPa and a recently introduced 1900 MPa grade. Focus has been to investigate weldability and the occurrence of cracks, porosity and strength reducing microstructure that can occur during laser welding, as well as distortion studies for tolerances in geometry. The results show that both conventional and 1900 MPa boron alloyed steel are suitable for laser welding.

    Due to the martensitic structure of welds the material tends to behave brittle. Cracking and porosity do not seem to be an issue limiting the use of these steels. For tolerances in geometry for larger structures tests has been done simulating laser welding of A-pillars and B-pillars. Measurements have been done with Vernier caliper as well as a more advanced optical method capturing the movements during the welding sequence. Results from the tests done on Ushaped beams indicates that depending on the geometry of the structure and heat input distortions can be controlled to give distortions from 1 to 8 mm, at a welding length of 700 mm. This means that important geometry points can be distorted several millimeters if the laser welding process not is controlled.

  • 47.
    Fahlström, Karl
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW). Swerea KIMAB, Joining Technology, Kista, Sweden .
    Andersson, Oscar
    Volvo Cars, Torslanda; XPRES, KTH Royal Institute of Technology.
    Todal, Urban
    Volvo Cars, Torslanda.
    Melander, Arne
    Swerea KIMAB, Joining Technology, Kista; XPRES, KTH Royal Institute of Technology, Stockholm.
    Minimization of distortions during laser welding of ultra-high strength steel2014Ingår i: ICALEO 2014 Congress proceedings, 2014, s. 1-10Konferensbidrag (Refereegranskat)
    Abstract [en]

    Ultra high strength steels are frequently used within the automotive industry for several components. Welding of these components is traditionally done by resistance spot welding, but to get further productivity and increased strength, laser welding has been introduced in the past decades. Fusion welding is known to cause distortions due to built-in stresses in the material. The distortions result in geometrical issues during assembly which become the origin of low joint quality due to gaps and misfits.

    U-beam structures of boron steel simulating B-pillars have been welded with laser along the flanges. Welding parameters and clamping have been varied to create different welding sequences and heat input generating a range of distortion levels. The distortions have been recorded dynamically with an optical measurement system during welding. In addition, final distortions have been measured by a digital Vernier caliper. The combined measurements give the possibility to evaluate development, occurrence and magnitude of distortions with high accuracy. Furthermore, section cuts have been analyzed to assess joint geometry and metallurgy.

    The results shows that final distortions appear in the range of 0-8 mm. Distortions occur mainly transversely and vertically along the profile. Variations in heat input show clear correlation with the magnitude of distortions and level of joint quality. A higher heat input in general generates a higher level of distortion with the same clamping conditions. Section cuts show that weld width and penetration are significantly affected by welding heat input.

    The present study identifies parameters which significantly influence the magnitude and distribution of distortions. Also, effective measures to minimize distortions and maintain or improve joint quality have been proposed.

    Finally, transient FE simulations have been presented which show the behavior of the profiles during the welding and unclamping process.

  • 48.
    Fahlström, Karl
    et al.
    Swerea KIMAB.
    Andersson, Oscar
    KTH Royal Institute of Technology.
    Todal, Urban
    Volvo Car Corporation.
    Melander, Arne
    Swerea KIMAB.
    Svensson, Lars-Erik
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för industriell produktion.
    Karlsson, Leif
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för naturvetenskap, lantmäteri- och maskinteknik.
    Distortion Analysis in Laser Welding of Ultra High Strength Steel2014Ingår i: Proceedings of the 6th International Swedish Production Symposium 2014 / [ed] Stahre, Johan, Johansson, Björn & Björkman, Mats, 2014, s. 1-9Konferensbidrag (Refereegranskat)
    Abstract [en]

    Due to increased demands on reduced weight in automotive industries, the use of ultra high strength steels (UHSS) has increased. When laser welding UHSS sheets, heating and cooling of the material will cause geometrical distortions and may cause low joint quality. 700 mm long U-beam structures of 1 mm thick boron steel simulating structural pillars in body-in-white constructions have been welded along the flanges with different welding speeds to investigate distortions and weld quality. The results show that final distortions appear in the range of 0-8 mm. FE simulation methods have also been presented which generally predict the distribution of welding distortions.

  • 49.
    Fuente, Raquel
    et al.
    IK4-LORTEK, Ordizia, Spain.
    García de la Yedra, Aitor
    IK4-LORTEK, Ordizia, Spain.
    Beizama, Ane Miren
    IK4-LORTEK, Ordizia, Spain.
    Fernández, Erik
    IK4-LORTEK, Ordizia, Spain.
    Gorostegui Colinas, Eider
    IK4-LORTEK, Ordizia, Spain.
    Echeverria, Alberto
    IK4-LORTEK, Ordizia, Spain.
    Broberg, Patrik
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för automationssystem.
    Thorpe, Nigel
    Tecnitest ingenieros, Madrid, Spain.
    Runnemalm, Anna
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för automationssystem.
    Henrikson, Per
    GKN Aerospace Engine Systems Sweden, Trollhättan, Sweden.
    Development and demonstration of an automated system for limited access weld inspection by using infrared active thermography2015Ingår i: Proceedings 7th International Symposium on NDT in Aerospace, Berlin, 2015, s. 1-8Konferensbidrag (Refereegranskat)
    Abstract [en]

    Weld inspection for surface breaking defects detection has been traditionally performed by using NDT methods such as Fluorescent PenetrantInspection (FPI), Visual Inspection (VI) or Eddy Currents (EC). All those well known techniques have as common drawback the need of skilled operator intervention in order to analyse obtained results. In the specific case of inspection of welds with limited access, the application of those traditional methods is even more complex, thus increasing inspection time and reducing the defect detection capability. Therefore, the development of a fully automated non-contact method overcoming these limitations is desired. Active thermography (IRT) represents one of the most promising techniques for replacing traditional techniques for surface breaking defect detection in welds.This technique makes use of an excitation source in order to heat the sample undertest and an infrared camera for thermal evolution monitoring. With the combination of these excitation-monitoring techniques, heterogeneities in the heat flow caused bysurface breaking cracks can be detected. In this work, a robotic solution was developed and demonstrated for the inspection of welds with real cracks in a representative environment with limited access. The system consists of a continuous laser-line excitation source together with a FLIR SC 655 micro bolometer thermographic camera. In order to access limited areas, two different aluminium polished mirrors have been used for bothinfrared radiation monitoring and laser excitation respectively. The inspection results, analysis and comparison with traditional methods will be shown.

  • 50.
    Garcia de la Yedra, Aitor
    et al.
    Control and Evaluation, IK4-LORTEK; Arranomendia Kalea 4A, Ordizia, Spain.
    Fernandez, Erik
    Control and Evaluation, IK4-LORTEK; Arranomendia Kalea 4A, Ordizia, Spain.
    Beizama, Ane Miren
    Control and Evaluation, IK4-LORTEK; Arranomendia Kalea 4A, Ordizia, Spain.
    Fuente, R.
    Control and Evaluation, IK4-LORTEK; Arranomendia Kalea 4A, Ordizia, Spain.
    Echeverria, A.
    Control and Evaluation, IK4-LORTEK; Arranomendia Kalea 4A, Ordizia, Spain.
    Broberg, Patrik
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för automationssystem.
    Runnemalm, Anna
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för automationssystem.
    Henrikson, Per
    GKN Aerospace Engine Systems.
    Defect strategies in Nickel Superalloys weld using active thermography2014Ingår i: 12th International Conference on Quantitative InfraRed Thermography, 7-11/7 Bordeaux, 2014, s. 1-9Konferensbidrag (Refereegranskat)
    Abstract [en]

    As a result of extreme operation conditions in gas turbines, high resistance materials with excellent behaviour at high temperature are required. Alloys, such as MarM-247 nickel based superalloy, with excellent mechanical properties at very high temperature (even at 85 % of their melting point) are being used in these applications. This extraordinary behaviour is mainly due to the presence of a strengthening phase (γ’) with the following chemical composition: Ni3(Al, Ti). However, during welding these materials are susceptible to cracking and this is why weld inspections become crucial. In this work different strategies for defect detection in welds are introduced, all of them based on active thermography. The work covers aspects such as different excitation and data evaluation strategies.

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