Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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Now showing 1 - 10 of 2092
  • Publication
    Wolframschmelzcarbidbasierte MMC-Schichten für den industriellen Einsatz im Formenbau
    ( 2022)
    Langebeck, Anika
    ;
    Jahnke, Christian
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    Wünderlich, Tim
    ;
    Hein, Christoph
    ;
    Bohlen, Annika
    ;
    Uhlmann, Eckart
    Zur Steigerung der abrasiven Verschleißbeständigkeit können Oberflächen lokal mit Hartpartikeln verstärkt werden. Diese sogenannten Metal-Matrix-Composit(MMC)-Schichten können mittels Laserstrahldispergieren gefertigt und durch Mikrofräsen nachbearbeitet werden. Im hier vorgestellten Forschungsvorhaben wurde als Grundwerkstoff verwendete Aluminiumbronze (CuAl10Ni5Fe4) mit Wolframschmelzcarbid verstärkt. Der Hartpartikelgehalt kann dabei durch eine Steigerung des Pulvermassenstroms bis zur Packungsdichte des unverarbeiteten Pulvers erhöht werden. Über eine temperaturbasierte Leistungsregelung kann eine gleichbleibend homogene MMC-Schicht mit konstanter Dicke und Tiefe dispergiert werden. Durch das Mikrofräsen mit optimierten Parametern können qualitativ hochwertige MMC-Oberflächen für den industriellen Einsatz in Spritzgusswerkzeugen hergestellt werden. Dabei wurde vor allem der Zahnvorschub fz als kritischer Prozessparameter identifiziert.
  • Publication
    Untersuchungen zur Beeinflussung der Geometrie und Werkstoffeigenschaften laserimplantierter Werkzeugstahloberflächen sowie zum tribologischen Einsatzverhalten
    (Fraunhofer Verlag, 2022)
    Spranger, Felix
    In einer Vielzahl technischer Anwendungen spielt die Schaffung und Aufrechterhaltung eines definierten tribologischen Verhaltens zwischen in Kontakt tretenden Wirkflächen für die Funktionalität von Bauteilen oder Werkzeugen eine entscheidende Rolle. Verfahren der Oberflächentechnik verfolgen das Ziel, entweder durch eine Manipulation der Werkstoffeigenschaften oder durch eine Strukturierung der Wirkfächen diese anzupassen. Obwohl erhabene Mikrostrukturen großes Potenzial zur gezielten Manipulation zeigen, wurden diese bislang wenig betrachtet, da sie anfällig für Verschleiß sind und nur schwer hergestellt werden können. Mit der Laserimplantation ist ein Verfahren bekannt, welches diese Hemmnisse überwindet und eine Generierung verschleißbeständiger, erhabener Mikrostrukturen (Implants) durch ein gepulstes Laserdispergieren keramischer Hartstoffpartikel in Wirkflächen zulässt. Um eine breite Nutzbarkeit zu erreichen, wird in dieser Arbeit eine Erweiterung des Prozessverständnisses forciert, sodass die geometrischen als auch werkstofftechnischen Implanteigenschaften zielgerichtet manipulierbar werden. Des Weiteren wird die tribologische Wirkweise implantierter Oberflächen betrachtet.
  • Publication
    Effects on crack formation of additive manufactured Inconel 939 sheets during electron beam welding
    ( 2022)
    Raute, Julius
    ;
    Jokisch, Torsten
    ;
    Biegler, Max
    ;
    Rethmeier, Michael
    The potential of additive manufacturing for processing precipitation hardened nickel-base superalloys, such as Inconel 939 is considerable, but in order to fully exploit this potential, fusion welding capabilities for additive parts need to be explored. Currently, it is uncertain how the different properties from the additive manufacturing process will affect the weldability of materials susceptible to hot cracking. Therefore, this work investigates the possibility of joining additively manufactured nickel-based superalloys using electron beam welding. In particular, the influence of process parameters on crack formation is investigated. In addition, hardness measurements are performed on cross-sections of the welds. It is shown that cracks at the seam head are enhanced by welding speed and energy per unit length and correlate with the hardness of the weld metal. Cracking parallel to the weld area shows no clear dependence on the process variables that have been investigated, but is related to the hardness of the heat-affected zone.
  • Publication
    PowerGrasp: Development Aspects for Arm Support Systems
    ( 2022)
    Goppold, J.-P.
    ;
    Kuschan, J.
    ;
    Schmidt, H.
    ;
    Krüger, J.
    Exoskeletons can support workers on physically demanding tasks, but in industry they lack of acceptance. This contribution gives an insight into design aspects for upper body exoskeletons, especially how active exoskeletons for industrial applications differ from military and medical use-cases. To overcome typical rigid exoskeleton problems, we suggest the use of modular soft-exosuit support systems and therefore checked different types of soft actuation principles for their eligibility for the use on upper body joints. Most promising approach is using two-layered actuators sting of robust fabric with embedded rubber tubes as pressure chambers. By inflating the tubes, it is possible to vary the stiffness of the chambers, which can be effectively used to generate assisting forces and moments at human joints (shoulder, elbow, wrist, finger).
  • Publication
    Literature review of quality attributes for collaborative product development
    ( 2022)
    Randermann, Marcel
    ;
    Blüher, Till
    ;
    Jochem, Roland
    ;
    Stark, Rainer
    In collaborative product development, diverse stakeholders are involved in distributed engineering activities. This situation makes it difficult to ensure, manage, and improve the quality across company boundaries. Therefore, this work determines the characteristics of collaborative engineering which have an influence on the quality of distributed product development. Several interoperability frameworks were analyzed in order to get insights into key areas for collaboration design. Furthermore, a systematic literature review provided the best practices for improvement efforts. The derived quality attributes were condensed and adapted to collaborative product development in the four key areas of organization and processes, data/artifacts, information technology systems and infrastructure, and social factors. This enables product developers to examine their collaborative engineering environment and to identify room for improvement and to enhance quality. A case example of an engineering change order shows a collaborative data flow process, in which the quality attributes may indicate improvement measures.
  • Publication
    High-power laser beam welding for thick section steels - new perspectives using electromagnetic systems
    ( 2022)
    Rethmeier, M.
    ;
    Gumenyuk, A.
    ;
    Bachmann, M.
    In recent years, it was shown that the introduction of additional oscillating and permanent magnetic fields to laser beam and laser-arc hybrid welding can bring several beneficial effects. Examples are a contactless weld pool support for metals of high thickness suffering from severe drop-out when being welded conventionally or an enhanced stirring to improve the mixing of added filler material in the depth of the weld pool to guarantee homogeneous resulting mechanical properties of the weld. The latest research results show the applicability to various metal types over a wide range of thicknesses and welding conditions. The observations made were demonstrated in numerous experimental studies and a deep understanding of the interaction of the underlying physical mechanisms was extracted from numerical calculations.
  • Publication
    Robot Inference of Human States: Performance and Transparency in Physical Collaboration
    ( 2022)
    Haninger, K.
    To flexibly collaborate towards a shared goal in human-robot interaction (HRI), a robot must appropriately respond to changes in their human partner. The robot can realize this flexibility by responding to certain inputs, or by inferring some aspect of their collaborator and using this to modify robot behavior-approaches which reflect design viewpoints of robots as tools and collaborators, respectively. Independent of this design viewpoint, the robot's response to a change in collaborator state must also be designed. In this regard, HRI approaches can be distinguished according to the scope of their design objectives: whether the design goal depends on the behavior of the individual agents or the coupled team. This chapter synthesizes work on physical HRI, largely in manufacturing tasks, according to the design viewpoint and scope of objective used. HRI is posed as the coupling of two dynamic systems; a framework which allows a unified presentation of the various design approaches and, within which, common concepts in HRI can be posed (intent, authority, information flow). Special attention is paid to predictability at various stages of the design and deployment process: whether the designer can predict team performance, whether the human can predict robot behavior, and to what degree the human behavior can be modelled or learned.
  • Publication
    High-stiffness Control of Series Elastic Actuators using a Noise Reduction Disturbance Observer
    ( 2022)
    Asignacion, A.
    ;
    Haninger, K.
    ;
    Oh, S.
    ;
    Lee, H.
    Rendering a high impedance on a series-elastic actuator (SEA) can improve motion control performance while retaining collision safety by a lower physical stiffness. The safe impedance range can be increased with high gain velocity feedback control, but in practice this is limited by noise. This paper applies the noise reduction disturbance observer (NRDOB) to inner-loop velocity control of an SEA, attenuating noise and allowing higher safe rendered stiffness compared with standard torque and torque/velocity hierarchical control. Closed-form expressions for maximum passive stiffness and Z-region are found, shown to depend strongly on the high-frequency noise gain, and used to optimize the control gains. Performance is experimentally verified on a reaction-force SEA; validating the passivity of the high stiffness control in impact (free space and stiff environment) while rendering a safe stiffness 3.0 times the intrinsic stiffness.
  • Publication
    Multiple-Wire Submerged Arc Welding of High-Strength Fine-Grained Steels
    ( 2022)
    Gook, S.
    ;
    El-Sari, Bassel
    ;
    Biegler, Max
    ;
    Rethmeier, Michael
    ;
    Lichtenthäler, F.
    ;
    Stark, M.
    Ensuring the required mechanical-technological properties of welds is a critical issue in the application of multi-wire submerged arc welding process for welding high-strength fine-grained steels. Excessive heat input is one of the main causes for microstructural zones with deteriorated mechanical properties of the welded joint, such as a reduced notched impact strength and a lower structural robustness. A process variant is proposed which reduces the weld volume as well as the heat input by adjusting the welding wire configuration as well as the energetic parameters of the arcs, while retaining the advantages of multi-wire submerged arc welding such as high process stability and production speed.
  • Publication
    Methodology for a reverse engineering process chain with focus on customized segmentation and iterative closest point algorithms
    ( 2022)
    Mönchinger, Stephan
    ;
    Schröder, Robert
    ;
    Stark, Rainer
    One-off construction is characterized by a multiplicity of manual manufacturing processes whereby it is based on consistent use of digital models. Since the actual state of construction does not match the digital models without manually updating them, the authors propose a method to automatically detect deviations and reposition the model data according to reality. The first essential method is based on the ""Segmentation of Unorganized Points and Recognition of Simple Algebraic Surfaces"" presented by Vanco et al.. The second method is the customization of the iterative closest point (ICP) algorithm. The authors present the overall structure of the implemented software, based on open source and relate it to the general reverse engineering (RE) framework by Buonamici et al.. A highlight will be given on: the general architecture of the software prototype; a customized segmentation and clustering of unorganized points and recognition of simple algebraic surfaces; the deviation analysis with a customized iterative closest point (CICP) algorithm Especially in the field of one-off construction, characterized by small and medium companies, automated assessment of 3D scan data during the design process is still in its infancy. By using an open source environment progress for consistent use of digital models could be accelerated.