Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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  • Publication
    PowerGrasp: Development Aspects for Arm Support Systems
    ( 2022)
    Goppold, J.-P.
    ;
    Kuschan, J.
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    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
    Simulation and compensation of the thermal behaviour of industrial robots
    ( 2021)
    Uhlmann, Eckart
    ;
    Polte, Julian
    ;
    Mohnke, Christian
    Industrial robot systems offer a flexible, adaptable basis due to their kinematics and their mobility. An influencing variable, which is particularly relevant for processes with long process times tP, is the thermal heating and the associated thermal drift ÎAPt of the tool center point. The maximum deviation from the actual nominal position can reach up to ÎAPt = 1.5 mm. In the investigations, a simulation model for an industrial robot was created and the thermal behaviour was mapped. With this model, the thermal error ÎAPt within the working area can be determined as a function of the current position X and temperature Ï. These data can be used for a targeted correction of the robot path. With the correction by the compensation model the amount of drift for real milling processes could be reduced to a value of ÎAPt = 0.042 mm. The results can help to reduce the influence of thermal heating and the associated thermal drift ÎAPt of the TCP without using cost-intens ive measures with additional hardware and software on external computers for compensating the errors.
  • Publication
    Additive manufacturing of precision cemented carbide parts
    ( 2021)
    Polte, Julian
    ;
    Polte, Mitchel
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    Lahoda, Christian
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    Hocke, Toni
    ;
    Uhlmann, Eckart
    Cemented carbide parts are commonly used as wear resistance components in a broad range of industry, e.g. for forming, mould making and matrices. At state of the art the machining of precision cemented carbide components by milling is strongly limited due to excessive tool wear and long machining times. Promising approaches for precision machining of cemented carbide components are dedicated cutting tool coatings, new cutting materials like binderless polycrystalline diamond and ultrasonic-assisted machining. Nevertheless, for all these approaches the components need to be machined of monolithic materials. The new approach addresses an innovative manufacturing process chain composed of near net shape Additive Manufacturing followed by a precision finishing process. Within this investigations for the manufacturing of precision cemented carbide parts, cemented carbide with a cobalt content of 17 % and a grain size in a range of 23 µm ⤠gs ⤠40 µm were used. As Addit ive Manufacturing technology laser powder bed fusion was used. Diamond slide burnishing and immersed tumbling were investigated as finishing technologies. Based on the investigations, a dedicated process chain for the manufacturing of precision cemented carbide parts could be realised. The findings show that the developed process chain composed of near net shape Additive Manufacturing and the finishing process diamond slide burnishing enables the manufacturing of precision cemented carbide parts with a geometrical accuracy of ag ⤠10 µm. Due to the finishing process the initial surface roughness after Additive Manufacturing could reduce by Ra = 89 %.
  • Publication
    Towards a Framework for Impact Assessment of Research & Technology Organisations
    ( 2021)
    Kidschun, Florian
    ;
    Hecklau, Fabian
    Due to their ability to bridge the gap between knowledge created by basic research and market requirements, Research and Technology Organisations (RTOs) play a major role in countriesâ innovation systems. Their R&D results should lead to innovations, which in turn generate the economic output of public investment in research and development. Moreover, they should support the foundation of new companies and industrial innovations. RTOs can thus be seen as intermediaries between R&D and the industry, while they themselves constitute to a certain extent entrepreneurs and actors in applied R&D that focus on industrial and commercial application right from the start of their activities. Therewith, RTOs pursue to increase the competitiveness of the entire economy. With a growing demand for evaluating their actual contribution in national innovation systems, simply stating the goal of positive impact to stakeholders like governments, the public, investors etc. is not enough; its accomplishment needs to be proven by robust evidence. In this regard, the value of an impact assessment is determined by the strength of the evidence produced and the credibility of the evaluation. RTOâs research activities and their impacts are diverse in nature and occur across many sectors of the economy. To gain transparent insights into relevant and comprehensive performance metrics showing the impact of RTOs from a micro- and macroeconomic perspective, impacts are only appropriate for evaluation if a causal relationship can be drawn back to their origin. While some impacts are primarily economic and suitable for quantitative analysis, others have to be evaluated qualitatively. Regardless of its type, each impact needs to be assessed within a common framework to enable a comprehensive understanding of RTO's impact. Within this contribution, an impact assessment framework is established with the aim to enable the identification of causal relationships between impacts and their origin.
  • Publication
    Time-Sensitive Networking over Metropolitan Area Networks for Remote Industrial Control
    ( 2021)
    Tschöke, Simon
    ;
    Lynker, Frederic
    ;
    Buhr, Hauke
    ;
    Schreiner, Florian
    ;
    Willner, Alexander
    ;
    Vick, Axel
    ;
    Chemnitz, Moritz
    The benefits of the currently evolving IEEE Time-Sensitive Networking (TSN) standard have already been globally recognized. Whereas the application of TSN in a LAN is currently widely and globally tested, TSN in a Metropolitan Area Network (MAN) has not been a major focus until now. The possible benefits of utilizing co-located Edge Clouds in order to support multiple urban production sites with industrial realtime applications open a wide range of new business models. Therefore, we have analyzed the feasibility of transparently using PROFINET over TSN via a Dense Wavelength Division Multiplex (DWDM) link, where a machine park is controlled remotely by an Edge-based virtual Programmable Logic Controller (vPLC). As a result, we are able to setup a TSN connection over a MAN with a one-way delay of about 156.5 J.ms and a jitter of about 12 ns. This work can be extended to allow for dynamically provisioned TSN flows and multi-path Frame Replication and Elimination (FRER) for distributed hard real-time machine control and adoption to Ultra-Reliable Low-Latency Communication (URLLC) 5G campus networks.
  • Publication
    Particle contact conditions for cutting edge preparation of micro-milling tools by the immersed tumbling process
    ( 2021)
    Uhlmann, Eckart
    ;
    Polte, Julian
    ;
    Kuche, Yves
    ;
    Landua, Fabian
    For increasing tool life and cutting length of micro-milling tools the cutting edge preparation was successfully established. Using the immersed tumbling process, a reproducible cutting edge preparation with constant cutting edge radii as well as low chipping of the cutting edges can be realised. For a profound understanding of the preparation process and the process mechanisms further knowledge about the particle interactions with cutting tools as well as the particle flow mechanisms needs to be obtained. In this investigation the preparation process of micro-milling tools was analysed and the contact-mechanisms as well as the resulting pressures were investigated by simulation studies. Using the discrete element method (DEM) with the software ROCKY DEM from the company ESSS, Florianópolis, Brasil, the immersed tumbling process could be modelled and particle contacts, particle traces as well as particle interactions with the micro-milling tool can be visualized. Especially the particle-tool interactions were more accurately investigated by analysing the stresses and particles shear work as well as correlations between these parameters to prove the comparability between the process simulation and the real preparation process.
  • Publication
    Interaction between capabilities of Model Based Systems Engineering on sensor models
    ( 2021)
    Manoury, Marvin Michael
    ;
    Schmidt, Simon
    ;
    Stark, Rainer
    In modern product development, models are often used for different purposes, e.g., system synthesis, trade-off analysis of system parameters or visualization and creation of design concepts. For some models, this purpose as well as the model itself might change over time. New interactions with the target system can occur and new details are added over time. Both have to be integrated immediately into the development procedure. When models are not maintained up to date and not used by different stakeholders, the benefits of the model-based approach are lessened due to the effort for generation and maintenance. The five development capabilities of MBSE, comprising Systems Environment Analytics (SEA), Systems Definition and Derivation (SDD), Systems Interaction Modeling (SIM), Systems Lifecycle Engineering (SLE) and the MBSE Capability and Maturation Matrix (CMM) address this topic on a capability level.In this article, the authors point out the interaction between these d evelopment capabilities on the example of a Pedestrian Emergency Braking System (PEBS) development in automotive industry, with a focus on sensor models. It will be shown exemplary how one development capability might influence another and how this interaction supports the development of complex systems.
  • Publication
    Reduction of erosion duration for electrical discharge drilling using a nature analogue algorithm with nested strategy types
    ( 2021)
    Uhlmann, Eckart
    ;
    Polte, Mitchel
    ;
    Streckenbach, Jan
    ;
    Osmanovic, Mirsad
    The required high economic efficiency, combined with the corresponding high quality demands, in the aerospace industry as well as in mould and tool making, motivate the necessity of finding suitable parameter combinations for the process of electrical discharge machining (EDM), e.g. when introducing new materials. To counteract this, various methods are being investigated in research for the optimisation of EDM. One new method is the stochastic optimisation procedure evolution strategy (ES). Due to its metaheuristic approach, this optimisation method is excellently suited for very complex processes in which the interrelationship of the individual influencing variables is not known. This publication presents the results of the investigation of the suitability of the ES optimisation method using the example of electrical discharge drilling. For this purpose, two nested ES-types were investigated. The electrode materials used were brass for the tool and stainless steel X5C rNi18-1 for the workpiece. As a result, the erosion duration could be reduced by 30 %. This investigation forms the basis for the use of nested ES types in electrical discharge drilling.
  • Publication
    Improved surface generation of multi-material objects in computed tomography using local histograms
    ( 2021)
    Uhlmann, Eckart
    ;
    Hein, Christoph
    ;
    Kayser, Nicolas
    ;
    Dürre, Gregor
    During the last decade industrial computed tomography (iCT) has become one of the most important metrological procedures for internal inspection, where it sees wide-spread use in injection molding and additive manufacturing. Evaluating the CT volume data of multi-material objects represents a major technical challenge. Due to artifacts caused by beam hardening, an over-segmentation of strongly absorbing materials occurs, severely limiting the accuracy of dimensional measurements. The goal of the project presented is the development of an innovative artifact-reduced multi-material segmentation. This is applied to and tested on various complex reconstructed CT data sets. Global approaches show high signal-to-noise-ratio (SNR) but are not able to compensate for local deviations. For smaller volumes the data sets become more consistent, but the SNR decreases due to the reduced data volume. Thus, a more localized approach for the volume image data has the potential to provid e results of higher accuracy. With this newly presented algorithm it is now possible to perform segmentation of all materials, while eliminating over-segmentation errors as well as local noise artifacts almost completely for all tested datasets.
  • Publication
    Simulating flow behaviour of wet particles within the immersed tumbling process
    ( 2021)
    Uhlmann, Eckart
    ;
    Polte, Julian
    ;
    Kuche, Yves
    ;
    Landua, Fabian
    For many production chains, it is mandatory to involve special finishing of the manufactured parts for the chipping of the edges as well as the polishing of surfaces. One commonly used method is the immersed tumbling process, where any workpiece is dragged through a particle filled container. In many cases, the immersed tumbling process operates in environments with added liquids, leading to changes in particle-tool interaction and general flow behaviour of the used particles. Whilst the discrete element method for simulating particles is mainly limited to dry particles, the used software ROCKY DEM from ESSS, Florianópolis, Brasil, comes with a built-in liquid-bridge model to simulate water-covered particles and granulate and furthermore an extension for system couplings with Ansys Fluent of the company ANSYS, INC., Canonsburg, Pennsylvania. The latter can be used to create from both software one three-phase-model with higher amounts of actually simulated water. In thi s study, small amounts of water were added to differently shaped particles using the build-in liquid-bridge model, to analyse and compare the particles flow characteristics in both, wet and dry environments. To gather significant information leading towards precise comparisons, the particles trajectories, velocities and resulting forces against the workpieces can be specifically observed and analysed, whilst this kind of process knowledge could previously never been taken into account without simulation.