Now showing 1 - 10 of 678
  • Publication
    Flexibles AM ermöglicht wettbewerbsfähige Produktion
    ( 2024-05) ;
    Fasselt, Janek Maria
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    Klötzer-Freese, Christian
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    Kruse, Tobias
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    Wagner, Florian
  • Publication
    AI-based welding process monitoring for quality control in large-diameter pipe manufacturing
    The paper presents the experimental results into the development of a multi-channel system for monitoring and quality assurance of the multi-wire submerged arc welding (SAW) process for the manufacture of large diameter pipes. Process signals such as welding current, arc voltage and the acoustic signal emitted from the weld zone are recorded and processed to provide information on the stability of the welding process. It was shown by the experiments that the acoustic pattern of the SAW process in a frequency range between 30 Hz and 2.5 kHz contains the most diagnostic information. In the spectrogram of the acoustic signal, which represents the time course of the frequency spectrum of the welding process, the formation of weld irregularities such as undercuts could be reliably identified. The on-line quality assessment of the weld seam produced is carried out in combination with methods of artificial intelligence (AI). From the results obtained, it can be concluded that the use of the latest concepts in welding and automation technology, combined with the high potential of AI, can achieve a new level of quality assurance in pipe manufacturing.
  • Publication
    Digital Twins within the Circular Economy: Literature Review and Concept Presentation
    ( 2024-03-26)
    Mügge, Janine
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    Seegrün, Anne
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    Hoyer, Tessa-Katharina
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    ;
    Digital twins offer a promising approach to sustainable value creation by providing specific life cycle data and enabling the monitoring and implementation of circular economy strategies throughout the product’s life cycle. By analyzing product, component, and material data, as well as process data, it is possible to create transparency throughout a product’s life cycle, build a data-driven product ecosystem, and establish new business and value creation models, from SMEs to large enterprises. This paper identifies application scenarios, their technological readiness level, and the challenges of digital twins for the circular economy in the manufacturing industry based on a systematic literature review. Gaps such as ensuring a continuous flow of information and taking into account the different levels of digitalization of companies are identified. As a main result, a holistic concept for the scoping of a digital twin for the circular economy is presented. One specific use case for end-of-life decision-making is elaborated upon. It is shown that the circular economy can be supported by digital twin data, especially for the optimal decision on end-of-life vehicles.
  • Publication
    Qualitätssicherung beim Laser-Pulver-Auftragschweißen
    ( 2024-02-01)
    In der modernen Fertigungstechnik spielt der Einsatz von korrosionsbeständigem Stahl eine große Rolle. Die kohlenstoffarme Edelstahllegierung 1.4404 (AISI 316L) ist ein häufig eingesetzter Werkstoff in der additiven Fertigung. Hier kann das Laser-Pulver-Auftragschweißen (LPA), engl. Directed Energy Deposition DED-LB, das weit verbreitete Laser Powder Bed Fusion (L-PBF) aufgrund höherer Auftragsraten und seiner Flexibilität in einigen Bereichen ergänzen und sogar ersetzen. Mit interessanten Perspektiven in der Bremsscheibenfertigung für Automobile.
  • Publication
    Numerical and experimental assessment of liquid metal embrittlement in externally loaded spot welds
    ( 2024-01-30)
    Prabitz, Konstantin
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    Antretter, Thomas
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    ; ;
    Schubert, Holger
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    Hilpert, Benjamin
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    Gruber, Martin
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    Sierlinger, Robert
    ;
    Ecker, Werner
    Zinc-based surface coatings are widely applied with high-strength steels in automotive industry. Some of these base materials show an increased brittle cracking risk during loading. It is necessary to examine electrogalvanized and uncoated samples of a high strength steel susceptible to liquid metal embrittlement during spot welding with applied external load. Therefore, a newly developed tensile test method with a simultaneously applied spot weld is conducted. A fully coupled 3D electrical, thermal, metallurgical and mechanical finite element model depicting the resistant spot welding process combined with the tensile test conducted is mandatory to correct geometric influences of the sample geometry and provides insights into the sample’s time dependent local loading. With increasing external loads, the morphology of the brittle cracks formed is affected more than the crack depth. The validated finite element model applies newly developed damage indicators to predict and explain the liquid metal embrittlement cracking onset and development as well as even ductile failure.
  • Publication
    KI zur Prozessüberwachung im Unterpulverschweißen
    Beim Unterpulverschweißen sind die Prozessgeräusche ein Indikator für eine gute Fügequalität. Diese Beurteilung kann i.d.R. nur von einer erfahrenen Fachkraft durchgeführt werden. Eine kürzlich entwickelte künstliche Intelligenz kann automatisch das akustische Prozesssignal anhand vortrainierter Merkmale klassifizieren und die Fügequalität anhand des Geräuschs beurteilen. Der Algorithmus, einmal richtig trainiert, kann den Prüfaufwand beim Unterpulverschweißen deutlich reduzieren.
  • Publication
    With synthetic data towards part recognition generalized beyond the training instances
    In this work we investigate the effect of using synthetic data, generated in a simulation, in order to pre-train an AI-based image classification for industrial components. After pre-training we use real camera-captured training images to fine-tune the AI with the aim to close the Sim2Real domain gap. We compare our approach to purely using real training images of a single candidate object instance. In an exemplary case study for screw recognition, we found that a given AI classification algorithm dropped its recognition rate from 99.8% to 88.5% when testing the algorithm with known and unknown screw instances of the learned object classes, respectively. Employing our pre-training method on the basis of synthetic data, the drop in recognition rate is decreased from 99% to 96.95%. Thus, our proposed method has only a relative drop of 2.05% when shifting towards a generalized domain (including unknown part instances), while a compared approach on the basis of real camera-captured data showed a drop of 11.3%.
  • Publication
    Energy efficiency measures for metal forming using hydraulic and mechanical presses
    ( 2024)
    Preuß, Mandy
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    Thiele, Gregor
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    Krüger, Jörg
    In conventional hydraulic presses only around 13 percent of the energy supplied is converted into the plastic forming of the metal. Mechanical presses achieve an overall efficiency of 13 to 30 percent. A variety of approaches aspire efficiency improvements by tuning process parameters. For the operation engineers it is a crucial task to find measures which are both technical suitable and economical promising. This paper summarizes popular tuning parameters and presents the assessment by seven experts who participated in semi-structured interviews. For hydraulic presses, the most recommend tuning parameter to be adjusted is the pressing force. For mechanical presses the continuous stroke operation is the most popular measure.
  • Publication
    Unified edge control for mobile robots based on VDA5050 and basys 4.0 - Architecture and interfaces
    ( 2024) ;
    Behling, Sebastian
    ;
    Gesien, Phillip
    ;
    Funk, Eugen
    Following the Industry 4.0 paradigm, flexible manufacturing systems are now researched and implemented to allow fast reaction on changing market conditions. The trend leads to the development of low volume and high mixture production. Here, automated guided vehicles (AGV) and autonomous mobile robots (AMR) interconnect machine tools and automated assembly stations. Current integration of mobile robots in industrial manufacturing processes often rely on single solutions by various equipment suppliers that are not compatible with each other. Extending the factory's intra-logistics with additional AGV applications results to raising number of control systems with specific MES-interfaces. To combine different mobile robots into a managed fleet with common master control is difficult and needs a lot of implementation effort. This work contributes with a proposed Unified Control System for Mobile Robots on three layers allowing direct control of robot tasks, single robots or even particular on-board components. The proposed unified interfaces extend the VDA5050 as a common specification towards a fully open mobile robot control system using ROS together with an AAS-based automation middleware BaSys 4.0. The experiments show the feasibility of such distributed control system for mobile robots even in unknown and unstructured environments. Three case studies were carried out to assess the installation time of mobile robots in new applications. This installation time is reduced to 30 minutes including mapping, definition of points-of-interest (POI) as well as first mission design.
  • Publication
    Kombination des Laserhybridschweißens und UP-Engspaltschweißens für dickwandige Bauteile zur Erhöhung der Wirtschaftlichkeit
    Dieser Beitrag befasst sich mit der Entwicklung eines wirtschaftlichen und robusten Verfahrens zum Schweißen dicker Stahlbleche. Es werden Ergebnisse für das Fügen von Blechen im Dickenbereich von 25 mm bis 80 mm vorgestellt. Die 30 mm dicken Schweißnähte konnten im Stumpfstoß in zwei Durchgängen unter Verwendung des Laserhybridschweißens und des Unterpulverschweißens (UP) geschweißt werden. Das Laserhybridschweißen wird als Einschweißung mit einer Tiefe von ca. 25 mm ausgeführt. Die UP-Lagen werden auf der gegenüberliegenden Seite des Blechs aufgebracht. Bei richtiger Wahl der Schweißparameter wird der Nahtquerschnitt durch eine sichere Überlappung beider Lagen geschlossen. Bei Blechdicken über 30 mm ist eine Kantenvorbereitung erforderlich, die eine Ausführung der UP-Fülllagen in Engspalttechnik ermöglicht. Die Vorteile der vorgeschlagenen Prozesskombination liegen darin, dass die Nahtwurzel der Laserhybridnaht nicht geformt werden muss. Defekte in der Wurzel der Laserhybrideinschweißung können durch die UP-Lagen effektiv beseitigt werden. Das Verfahren bietet eine hohe Stabilität des Schweißprozes-ses in Bezug auf die Qualität der Blechkanten. Plasmageschnittene Kanten konnten ohne Bindefehler geschweißt werden. Die erreichte Nahtqualität wurde durch zerstörende und zerstörungsfreie Prüfungen bestätigt.