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Simulation of friction between diamond and polycrystalline cubic boron nitride

Procedia CIRP 2021年 104卷 44-49页

作者： Ulrich Müller Sebastian Prinz Sebastian Barth Thomas Bergs Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University Campus-Boulevard 30 52074 Aachen Germany Fraunhofer Institute for Production Technology IPT Steinbachstraße 17 52074 Aachen Germany

Grinding is a key technology in the manufacturing chain of polycrystalline cubic boron nitride (PCBN) cutting tools. However, high wear and low material removal rates during grinding lead to high manufacturing costs of PCBN cutting tools. Since friction is a major driver of grinding wheel wear, the friction related temperature between diamond as abrasive grain and PCBN as cutting tool material was investigated using the finite element method. Maximum temperatures of up to 720 °C and average temperatures of up to 165 °C were found on the PCBN surface depending on the PCBN specification, the friction coefficient, and the relative velocity.

关键词： Friction grinding polycrystalline cubic boron nitride

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Development of handling system concepts for additive process chains with Laser Powder Bed Fusion (L-PBF)

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Procedia CIRP 2021年 104卷 1173-1178页

作者： Rainer Horstkotte Florian Heinrich Marcel Prümmer Kristian Arntz Thomas Bergs Fraunhofer Institute for Production Technology IPT Steinbachstraße 17 52074 Aachen Germany Laboratory for Machine Tools and Production Engineering (WZL) RWTH Aachen University Campus-Boulevard 30 52074 Aachen Germany

Laser Powder Bed Fusion (L-PBF) is an additive manufacturing (AM) technology that enables the production of highly complex and individualized metal components. Since these components need post-processing, L-PBF is usually utilized within a manufacturing process chain. The automation of this process chain is a crucial step towards the industrialization of L-PBF. This paper presents a methodology for the conceptual design of handling systems for the automated handling of L-PBF components. It includes the selection of gripping and clamping devices, robots, and other peripheral systems. Restrictions that arise from the complexity of the components and the technologies are considered.

关键词： Additive manufacturing AM Laser Powder Bed Fusion L-PBF Process chain Automation Automated handling Automated gripping Automated clamping Automation concepts Post-processing Handling systems

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Life cycle assessment for milling of Ti- and Ni-based alloy aero engine components

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Procedia CIRP 2021年 98卷 625-630页

作者： Thomas Bergs Timm Grünebaum Kilian Fricke Sebastian Barth Philipp Ganser Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University Campus-Boulevard 30 52074 Aachen Germany Fraunhofer Institute for Production Technology IPT Steinbachstr. 17 52074 Aachen Germany

Motivation : Aero engine optimization focuses on reducing emissions during operation. Resource extraction and manufacturing are considered insufficiently. An LCA of resource extraction and machining for aero engine components comparing a Ti-alloy and a Ni-alloy was conducted. Method : Aero engine components were manufactured comparing a Ti-alloy and a Ni-alloy. Results : Machining mostly affects climate change, water use, resource depletion and human toxicity. The Ni-alloy showed an overall higher environmental impact than the Ti-alloy. Conclusion : Raw material, tool life and energy usage significantly contribute to environmental impacts. Further investigation should focus on tool life travel path optimization and reducing raw material.

关键词： Life Cycle Assessment Production technology Aero Engineering Blade Integrated Disk technology Planning

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Development of measuring systems for contact force and relative velocity in robot-guided centrifugal finishing

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Procedia CIRP 2021年 104卷 14-19页

作者： Marius Ohlert Tim Schriever Sebastian Prinz Sebastian Barth Thomas Bergs Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University Campus-Boulevard 30 52074 Aachen Germany Fraunhofer Institute for Production Technology IPT Steinbachstr. 17 52074 Aachen Germany

Robot-guided centrifugal finishing is capable of reducing the surface roughness and inducing residual compressive stresses into the edge zone of the component to enhance the fatigue strength. Due to an insufficient understanding of robot-guided centrifugal finishing processes, it is not possible to adjust the process result in a knowledge-based manner. In order to understand the mechanisms of action in the process, knowledge of the contact force and the relative velocity between abrasive media and workpiece is necessary. Therefore, in this work measuring systems for the measuring of the contact force and the relative velocity were developed and validated to close this knowledge gap.

关键词： Robot-guided centrifugal finishing abrasive media contact force relative velocity

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The dynamics of a driven harmonic oscillator coupled to pairwise interacting Ising spins in random fields

arXiv

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arXiv 2020年

作者： Zech, Paul Otto, Andreas Radons, Günter Institute of Physics Chemnitz University of Technology Chemnitz09107 Germany Fraunhofer Institute for Machine Tools and Forming Technology Chemnitz09126 Germany Institute of Mechatronics Chemnitz09126 Germany

In general we are interested in dynamical systems coupled to complex hysteresis. Therefore as a first step we investigated recently the dynamics of a periodically driven damped harmonic oscillator coupled to independent Ising spins in a random field. Although such a system does not produce hysteresis, we showed how to characterize the dynamics of such a piecewise-smooth system, especially in the case of a large number of spins [P. Zech, A. Otto, and G. Radons, Phys. Rev. E 101, 042217 (2020)]. In this paper we extend our model to spin dimers, thus pairwise interacting spins. We show in which cases two interacting spins can show elementary hysteresis and we give a connection to the Preisach model, which allows us to consider an infinite number of spin-pairs. This thermodynamic limit leads us to a dynamical system with an additional hysteretic force in the form of a generalized play operator. By using methods from general chaos theory, piecewise-smooth system theory and statistics we investigate the chaotic behavior of the dynamical system for a few spins and also in case of a larger number of spins by calculating bifurcation diagrams, Lyapunov exponents, fractal dimensions and self-averaging properties. We find that the fractal dimensions and the magnetization are in general not self-averaging quantities. We show, how the dynamical properties of the piecewise-smooth system for a large number of spins differs from the system in its thermodynamic limit. Copyright © 2020, The Authors. All rights reserved.

关键词： Hysteresis

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Surface Integrity of Wire Electrochemical machined Inconel 718

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Procedia CIRP 2022年 108卷 152-157页

作者： T. Herrig L. Heidemanns L. Ehle T.E. Weirich T. Bergs Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University Campus-Boulevard 30 52074 Aachen Germany Central Facility for Electron Microscopy (GFE) RWTH Aachen University Ahornstraße 55 52074 Aachen Germany Fraunhofer Institute for Production Technology IPT Steinbachstraße 17 52074 Aachen Germany

Wire electrochemical machining (wire ECM) combines the advantages of wire electrical discharge machining (wire EDM) and electrochemical machining (ECM). The advantages of flexible 2.5 dimensional machining without the need for an application-specific fixture are combined with the excellent surface integrity properties of the ECM. These properties make the process particularly suitable for highly critical components, like fir tree slots in turbine discs. Knowledge of the resulting surface integrity in terms of microstructure formation, oxide layers, etc. is essential for such components. Therefore, in this paper modified rim zones are investigated by wire ECM e.g. with energy filtered transmission electron microscopy.

关键词： Wire ECM Surface Integrity Fir tree slots EFTEM

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Parametric compensation scheme for increasing the geometrical accuracy of lattice structures in medical implants produced by powder bed fusion 54

Parametric compensation scheme for increasing the geometrica...

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54th CIRP Conference on Manufacturing Ssystems, CMS 2021

作者： Horn, Max Koch, Lukas Schafnitzel, Mario Schmitt, Matthias Schlick, Georg Schilp, Johannes Reinhart, Gunther Fraunhofer Institute for Casting Composite and Processing Technology IGCV Am Technologiezentrum 10 Augsburg86159 Germany University of Augsburg Department of Digital Manufacturing Faculty of Applied Computer Sience Eichleitnerstr. 30 Augsburg86159 Germany Technical University of Munich Institute for Machine Tools and Industrial Management Boltzmannstr. 15 Garching n. Munich85748 Germany

Powder bed fusion of metals by laser beam enables the production of porous lattice structures that facilitate bone ingrowth and the vascularization of medical implants. Comprehensive implementation is currently limited by the medium reproducibility of porous structures with insufficient dimensional accuracy. Therefore strategies for minimizing geometrical mismatch and roughness are investigated by way of experiment. A parametric compensation scheme that takes into account the melt pool depth of the struts' downskins in reducing the geometric mismatch between as-designed and as-built lattice structures is proposed. Build angles of 10° with respect to the platform were created without support structures. © 2021 Elsevier B.V.. All rights reserved.

关键词： 3D printers

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Touch-based Augmented Reality Marking Techniques on Production Parts

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Procedia CIRP 2022年 107卷 517-521页

作者： Arno Schmetz Martin Bellgardt Vincent Wehrwein Torsten Kuhlen Christian Brecher Fraunhofer Institute for Production Technology IPT Steinbachstr. 17 Aachen 52074 Germany Fraunhofer Research Institution for Battery Cell Production FFB Mendelstr. 11 Münster 48149 Germany Visual Computing Institute RWTH Aachen University Kopernikusstr. 6 Aachen 52074 Germany Laboratory for Machine Tools WZL RWTH Aachen University Steinbachstr. 19 Aachen 52074 Germany

In the machining of production parts, the quality of the surface is subject to a variety of influences. Tool wear, thermal effects and vibrations can affect the surface quality of the machined object drastically. Some of those effects on the surface, like marks from vibrations, can be seen by machining experts directly on the object without measurement hardware or metrology systems. Those pieces of information held by the experts are valuable to the surface finishing staff, the metrology staff and data scientists, who could use them to improve both the product and the process. However, to enable this exchange of information, the relevant data needs to be indicated in a spatially resolved and machine-readable format. Additionally, the experts need to be able to mark the areas for all kinds of different requirements in a fast and suitable manner without possibly damaging the part itself. Our approach for this task is using a touch-based Augmented Reality system that allows the users to mark these areas of interest on the production part digitally without touching the production part itself. Therefore, we propose two different marking techniques - Shift&Freeze Marking and Relative Marking - based on literature from pointing tasks. We performed user trials to evaluate the usability, task load and overall performance of those techniques showing a general suitability for touch-based AR marking of relevant regions on productions parts.

关键词： Augmented Reality Data Augmentation Data Preprocessing Industry 4.0

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Retrieving properties of manufacturing systems from traceability data for performance evaluation and material flow simulation

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Procedia CIRP 2021年 104卷 20-25页

作者： Heiner Reinhardt Marc Münnich Bastian Prell Roman Arnold Fabian Krippner Marek Weber Frank Seifert Matthias Putz Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Straße 88 09126 Chemnitz Germany Technical University of Applied Science Wildau Hochschulring 1 15745 Wildau Germany Volkswagen Sachsen GmbH Motorenwerk Chemnitz Kauffahrtei 47 09120 Chemnitz Germany Chemnitz University of Technology Straße der Nationen 62 09111 Chemnitz Germany

The operation of manufacturing systems is increasingly accompanied by data-driven continuous improvement processes and product traceability is required. Commonly, radio-frequency identification (RFID) technology is applied to track the flow of a uniquely-identifiable workpiece along various stations or waypoints within a factory. Based on an automotive use case, this paper describes how to analyze the resulting traceability data in order to identify several properties of a manufacturing system. The acquired knowledge can support performance evaluation and facilitate model building for material flow simulation as a foundation for digital twins and cyber-physical production systems.

关键词： Knowledge management Algorithm Analysis Condition monitoring Manufacturing system Complexity Man-machine system Pattern recognition

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Methodology for the self-optimizing determination of additive manufacturing process eligibility and optimization potentials in toolmaking

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Procedia CIRP 2022年 107卷 1539-1544页

作者： Tammo Dannen Benedikt Schindele Marcel Prümmer Kristian Arntz Thomas Bergs Laboratory for Machine Tools and Production Engineering (WZL) RWTH Aachen University Campus-Boulevard 30 52074 Aachen Germany Fraunhofer Institute for Production Technology IPT Steinbachstraße 17 52074 Aachen Germany Lehrstuhl für Fertigungsverfahren und Werkzeugmaschinen FH Aachen Goethestraße 1 52064 Aachen Germany

Additive Manufacturing (AM) of metallic workpieces faces a continuously rising technological relevance and market size. Producing complex or highly strained unique workpieces is a significant field of application, making AM highly relevant for tool components. Its successful economic application requires systematic workpiece based decisions and optimizations. Considering geometric and technological requirements as well as the necessary post-processing makes deciding effortful and requires in-depth knowledge. As design is usually adjusted to established manufacturing, associated technological and strategic potentials are often neglected. To embed AM in a future proof industrial environment, software-based self-learning tools are necessary. Integrated into production planning, they enable companies to unlock the potentials of AM efficiently. This paper presents an appropriate methodology for the analysis of process-specific AM-eligibility and optimization potential, added up by concrete optimization proposals. For an integrated workpiece characterization, proven methods are enlarged by tooling-specific figures. The first stage of the approach specifies the model’s initialization. A learning set of tooling components is described using the developed key figure system. Based on this, a set of applicable rules for workpiece-specific result determination is generated through clustering and expert evaluation. Within the following application stage, strategic orientation is quantified and workpieces of interest are described using the developed key figures. Subsequently, the retrieved information is used for automatically generating specific recommendations relying on the generated ruleset of stage one. Finally, actual experiences regarding the recommendations are gathered within stage three. Statistic learning transfers those to the generated ruleset leading to a continuously deepening knowledge base. This process enables a steady improvement in output quality.

关键词： Additive manufacturing AM Laser-Powder Bed Fusion L-PBF Binder Jetting BJ Directed Energy Deposition DED Clustering Cluster analysis Candidate selection Part identification Workpiece optimization Tooling Key figure system Process automation Manufacturing process selection Software

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