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23rd International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2023

作者： Schuster, Alexander Otto, Andreas Rentzsch, Hendrik Ihlenfeldt, Steffen Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 Chemnitz09126 Germany

ISBN: (纸本)9781998999132

In-process monitoring in milling, specifically tool condition monitoring (TCM), is an important technology for improving productivity and workpiece quality. However, industrial implementation of in-process TCMs remains a difficult task, since progressing tool wear is indicated by small changes of various physical parameters. Therefore, a sensitive monitoring system is needed to provide a reliable base of information while having minimal impact on the machine tool system and processes. Recent advancements in deep learning (DL) techniques are frequently applied on monitoring data for tool wear prediction as they can process and analyse raw data without prior feature engineering. This paper presents a suitable monitoring approach based on a recently developed sensory tool holder, which measures cutting forces and vibrations in direct proximity to the process zone. The system is equipped with wireless data transmission and a novel energy harvesting technology for energy supply. Two milling experiments with focus on increasing tool wear were conducted and the collected data processed. A DL based model, comprising three convolutional neural network (CNN) layers, one long short-term memory (LSTM) layer, and a multi-layer perceptron (MLP), was trained on the raw sensor signals to make predictions on the tool wear state. The model was evaluated using previously unseen test data and achieved a high prediction accuracy of at least 97,3% for all sensor signals, with the highest accuracy of 99,9% achieved when using bending moment signals. © 2023 Euspen Headquarters.

关键词： Milling (machining)

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Energy self-sufficient, multi-sensory tool holder for sensitive monitoring of milling processes 19

Energy self-sufficient, multi-sensory tool holder for sensit...

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19th CIRP Conference on Modeling of Machining Operations, CMMO 2023

作者： Schuster, Alexander Rentzsch, Hendrik Ihlenfeldt, Steffen Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 Chemnitz09126 Germany

Machining processes, especially milling, place several requirements on monitoring systems. Two prevalent ones are minimal implications towards the machine tool system and direct proximity to the machining zone to acquire high signal quality. Thereby, sensitive detection of even minor process alterations is enabled. This paper presents a suitable monitoring approach based on a sensory tool holder. An innovative wireless energy harvesting technology using spindle rotation is implemented. Obtained signal data for exemplary milling processes as well as corresponding signal analysis strategies are presented. © 2023 Elsevier B.V.. All rights reserved.

关键词： Cutting tools

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Dismantling and remanufacturing strategies in the automotive sector 31

Dismantling and remanufacturing strategies in the automotive...

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31st CIRP Conference on Life Cycle Engineering, LCE 2024

作者： Haase, Rico Farioli, Daniele Selbmann, Rene Werner, Markus Kräusel, Verena Fraunhofer Institute for Machine Tools and Forming Technology Chemnitz09126 Germany Politecnico di Milano Department of Mechanical Engineering Milan20156 Italy

The contemporary recycling of automobiles takes place on a very baseline material level. In order to fundamentally improve the ecologic footprint of the vehicle, a wider application of remanufacturing strategies is intended. Following different recycling approaches ranging from direct reuse or refurbishment through remanufacturing until repurpose, a well-aimed dismantling followed by manufacturing processes adapted to the post-consumer components is mandatorily required. For use on an industrial scale, environmental efficiency and economic viability must be balanced well. Within the paper, possible remanufacturing technologies and necessary prerequisites such as input data are discussed. For the design of remanufacturing operations, material properties and geometric information are a crucial starting point. Seamless integration of the specific properties is intended to encourage wider utilization of pre-used components and materials. With reference to the well-established process design for metal forming operations, adapted material cards and curvature equivalence values are proposed. The approach is illustrated by a reforming operation, where a brake disc cover is remanufactured from a used car body roof. © 2024 Elsevier B.V.. All rights reserved.

关键词： Recycling

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Reducing noise and vibrations in wind power plants with DFIG and planetary gearbox through improved rotor current control 56

Reducing noise and vibrations in wind power plants with DFIG...

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56th International Conference on Vibroengineering

作者： Windisch, Thomas Hensel, Eric Drossel, Welf-Guntram Fraunhofer-Institute for Machine Tools and Forming Technology IWU Chemnitz Germany

Planetary gears in wind power plants transmit force excitations to the mechanical structure due to alternating tooth meshes. Structure-borne sound is generated and proceeds to tower and nacelle where it is radiated to the environment and may be a noise pollution to residents. In addition, unwanted vibrations can decrease the durability of the gearbox. So far, structural vibrations are being avoided by constructive measures or active absorbers. In contrast to this, our approach is to reduce gear mesh excitations only with the existing electric generator. Therefore, the rotor current control of the machine is enhanced to inject high frequency oscillations so that the wind power generator produces a specific oscillating torque. This anti-noise torque ripple is transmitted via the shaft to the gear stage and minimizes the gear mesh orders so that less force excitations are exposed to the mechanical structure at the bearings. In our knowledge this anti-noise torque approach using the electric generator and its current control is completely new in the field of wind power plants. Simulation is performed using a multi-body-model of the drivetrain to identify an optimal torque oscillation. Afterwards a control circuit model of the generator and the power converter for the rotor circuit is shown. Hence, it is possible to calculate the behavior of the system in high level of detail on the mechanical and the electrical side. Resulting bearing forces are analyzed to prove that excitation can be reduced significantly. No additional hardware, especially no additional actor is needed. Copyright © 2022 Thomas Windisch, et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

关键词： Acoustic noise

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Pattern matching for mathematical expressions with OpenMath 14

Pattern matching for mathematical expressions with OpenMath

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Joint of the 5th Workshop on Formal Mathematics for Mathematicians, FMM 2019, 2nd Workshop on Formal Verification of Physical Systems, FVPS 2021, 13th Workshop on Mathematical User Interaction, MathUI 2021, 2021 Workshop on Natural Formal Mathematics, NatFoM 2021, and 31st OpenMath Workshops, OM 2021 Doctoral Program and Work in Progress at the 14th Conference on Intelligent Computer Mathematics, CICM-WS 2021

作者： Wenzel, Ken Fraunhofer-Institute for Machine Tools and Forming Technology IWU Chemnitz Germany

An OpenMath Content Dictionary with symbols for pattern matching of tree-like structures is presented. Furthermore, a mapping to RDF and SPARQL is introduced that allows to execute search queries against an OpenMath R... 详细信息

关键词： Pattern matching

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Simulation concept for surface designs increasing the coefficient of static friction 22

Simulation concept for surface designs increasing the coeffi...

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22nd International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2022

作者： Walther, Franz Wieland, Sebastian Schneider, Jörg Edelmann, Jan Fraunhofer Institute for Machine Tools and Forming Technology IWU Chemnitz Germany

ISBN: (纸本)9781998999118

The objective of the simulation concept for the design of surfaces is the prediction of trends relating to the coefficient of static fric-tion of two friction partners. For the overall consideration, further influencing variables have to be considered, since an exclusive focus on the coefficient of static friction can only inadequately describe the complex tribological behaviour when two surfaces come into contact. To calculate these characteristic values, a multi-stage simulation and calculation approach was developed in which, starting from the generation of experimentally measured or artificially generated surface topography data (stage 1), the true contact area as well as the stress and deformation behaviour when two surfaces come into contact are simulated in contact simula-tions (stage 2). Finally, the coefficient of static friction is calculated based on a micro-roughness model taken from the literature and statistical homogenization (stage 3). The accuracy and validity of the workflow was demonstrated in the experimental valida-tion using ground sample surfaces. Trends with regard to the coefficients of static friction were reliably represented. In addition a method for generating synthetic stochastic surfaces as simulation input was developed. Due to the given comparability with experi-mental surfaces in terms of the geometric properties and the resulting friction behaviour, virtual surfaces can also be used in the future as input of the multistage calculation workflow and applied in simulative parameter studies. © European Society for Precision Engineering and Nanotechnology, Conference Proceedings - 22nd International Conference and Exhibition, EUSPEN 2022. All rights reserved.

关键词： Surface roughness

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OpenMath-RDF: RDF encodings for OpenMath objects and Content Dictionaries 14

OpenMath-RDF: RDF encodings for OpenMath objects and Content...

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作者： Wenzel, Ken Fraunhofer-Institute for Machine Tools and Forming Technology IWU Chemnitz Germany

This paper presents RDF encodings for OpenMath objects and Content Dictionaries that allow mathematical objects and symbol definitions to be first-class citizens on the Web of Data. © 2022 Copyright for this pape... 详细信息

关键词： Encoding (symbols)

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Investigation of alternative attention modules in transformer models for remaining useful life predictions: addressing challenges in high-frequency time-series data

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Procedia CIRP 2024年 122卷 85-90页

作者： Eugen Boos Jan Zimmermann Hajo Wiemer Steffen Ihlenfeldt Technische Universität Dresden Fraunhofer Institute for Machine Tools and Forming Technology

Predicting the Remaining Useful Life of a machine components or systems is a pivotal technology in condition-based maintenance and essential for ensuring the reliability and safety in various production-engineering applications. The influx of extensive industrial data has notably enhanced the efficacy of data-driven Remaining Useful Life prediction models, especially deep learning models. One of the promising deep learning model architectures is the Transformer-based model with the Self-Attention mechanism at its core. However, inherent limitation arise when applying Self-Attention to high- frequency time-series data with large window sizes. Due to its high computational complexity, hardware limitations hinder the practical implementation of Transformer with Self-Attention in production-engineering applications. This study looks into the utilization of alternative Attention modules with reduced complexity, making it more applicable to high-frequency time-series data. In order to allow comparability, this study uses the well-known C-MPASS dataset for benchmarking Remaining Useful Life approaches. Although this dataset does not consist of high-frequency data, it demonstrates the usefulness of alternative Attention modules without noteworthy losses in model accuracy.

关键词： Remaining useful life Attention Complexity Transformer Deep learning

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Design, Fabrication and Characterization of a Novel Variable Stiffness Structure for Soft Continuum Robotics

Design, Fabrication and Characterization of a Novel Variable...

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International Joint Conference on Mechanics, Design Engineering and Advanced Manufacturing, JCM 2022

作者： Weisheit, Linda Wockenfuß, Wilhelm Richard Fraunhofer Institute for Machine Tools and Forming Technology IWU Nöthnitzer Straße 44 Dresden01187 Germany

ISBN: (纸本)9783031159275

Soft Robotics made of soft and compliant materials ensure systems with high inherent safety for a safe human-robot collaboration. Thereby current soft robots mostly lack the required stiffness to apply sufficient loads. To ensure inherent safety and at the same time a greater load capacity, structures with adjustable stiffness are required. In this paper, possible approaches for the realization of a switchable stiffness are analyzed and evaluated against the application background of human-oriented soft robotics, which focus mainly on high switching dynamics and high stiffness ratios. A concept for variable stiffness robotic segments based on particle and layer jamming for planar motion is shown, enabling highly dynamic switching between stiff and soft with a bending stiffness ratio K > 100. For this variable stiffness structural component, both the development steps and the characterization methodology are explained. Finally, an outlook on the design of a soft continuum robotic manipulator using three of these variable stiff segments and two tendons for an underactuated motion control of the whole structure is given. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.

关键词： Stiffness

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Operational modal analysis used to identify dynamic behaviour of machine tools during milling 16

Operational modal analysis used to identify dynamic behaviou...

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16th CIRP Conference on Intelligent Computation in Manufacturing Engineering, CIRP ICME 2022

作者： Berthold, Jan Regel, Joachim Dix, Martin Drossel, Welf-Guntram Institute for Machine Tools and Production Processes Chemnitz University of Technology Reichenhainer Str. 70 Chemnitz09126 Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 Chemnitz09126 Germany

The dynamic behaviour of machine tools during cutting is investigated by Operational Modal Analysis (OMA), which overcomes the disadvantages of the Experimental Modal Analysis (EMA) using excitation methods such as shakers or hammers, not considering effects occurring during operation. The assumptions of OMA such as time-invariance and white noise excitation are difficult to fulfil considering the boundary conditions of a milling process. The results show that feed motions classify the varying dynamic behaviour in the working space and excitation is controlled by modification of the milling conditions. Modal Parameters, identified by OMA, provide process-related results enabling to improve performance. © 2023 Elsevier B.V.. All rights reserved.

关键词： machine tools

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