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arXiv 2024年

作者： Weichert, Dorina Kister, Alexander Houben, Sebastian Link, Patrick Ernis, Gunar Fraunhofer Institute for Intelligent Analysis and Information Systems IAIS Sankt Augustin Germany VP.1 eScience Federal Institute for Materials Research and Testing BAM Berlin Germany University of Applied Sciences Bonn-Rhein-Sieg Sankt Augustin Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Chemnitz Germany Institute of Mechatronic Engineering TUD Dresden University of Technology Dresden Germany

The practical use of Bayesian Optimization (BO) in engineering applications imposes special requirements: high sampling efficiency on the one hand and finding a robust solution on the other hand. We address the case of adversarial robustness, where all parameters are controllable during the optimization process, but a subset of them is uncontrollable or even adversely perturbed at the time of application. To this end, we develop an efficient information-based acquisition function that we call Robust Entropy Search (RES). We empirically demonstrate its benefits in experiments on synthetic and real-life data. The results show that RES reliably finds robust optima, outperforming state-of-the-art algorithms. © 2024, CC BY-SA.

关键词： Entropy

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Automated porosity assessment of parts produced by Laser Powder Bed Fusion using Convolutional Neural Networks

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Procedia CIRP 2021年 104卷 1434-1439页

作者： Jan Klein Martin Jaretzki Michael Schwarzenberger Steffen Ihlenfeldt Welf-Guntram Drossel Technische Universität Dresden Chair of Machine Tools Development and Adaptive Controls 01069 Dresden Fraunhofer Institute for Machine Tools and Forming Technology (IWU) Nöthnitzer Str. 44 01187 Dresden Germany

Laser Powder Bed Fusion (LPBF) is especially interesting for applications in industries with high quality requirements. There are different expensive and time-consuming strategies for quality assurance. A cheaper and faster approach is to analyze the data acquired during fabrication. In this work Convolutional Neural Networks (CNN) are investigated as a tool for data analysis of meltpool monitoring data. The goal is to automatically distinguish between porous and non-porous part regions. Therefore, the training data is categorized based on CT-scans of the test specimens. For increased interpretability of the results, Gradient-Weighted Class Activation Maps (Grad-CAM) are used.

关键词： Additive Manufacturing Laser Beam Melting LPBF Process Monitoring Quality Assessment Porosity In-process sensing Melt pool monitoring CNN Neural Networks

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Geometric empirical modelling of forces influenced by the cutting edge microgeometry in orthogonal cutting of unidirectional CFRP 18

Geometric empirical modelling of forces influenced by the cu...

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18th CIRP Conference on Modeling of Machining Operations, CMMO 2021

作者： Sauer, Konstantin Nowak, Alexander Regel, Joachim Wertheim, Rafael Dix, Martin Chemnitz University of Technology Professorship Production Systems and Processes Reichenhainer Strasse 70 Chemnitz09126 Germany Chemnitz University of Technology Professorship Machine Elements and Product Development Reichenhainer Strasse 70 Chemnitz09126 Germany Fraunhofer Institue for Machine Tools and Forming Technology Reichenhainer Strasse 88 Chemnitz09126 Germany

In optimising the cutting of carbon fibre reinforced plastics (CFRP), increasing emphasis is placed on the cutting edge microgeometry. A significant challenge lies in understanding the engagement conditions between tool and workpiece, influencing tool wear mechanisms and performance. This paper aims to provide a more in-depth insight into the influence of cutting parameters on process forces when applying ideally rounded cutting edges in orthogonal cutting. A geometric empirical process model is developed for calculating the cutting force and the passive force, considering the cutting edge radius, the uncut chip thickness, and the fibre cutting angle. As a result, the minimum uncut chip thickness was determined, and process forces were calculated. © 2021 Elsevier B.V.. All rights reserved.

关键词： Carbon fiber reinforced plastics

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Influence of engagement parameters on estimation of tangential cutting force using high-frequency process data of the machine tool

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Procedia CIRP 2023年 118卷 537-542页

作者： Michal Rytir Jonas Rönnecke Albrecht Hänel Petr Kolar Steffen Ihlenfeldt Czech Technical University in Prague Czech Institute of Informatics Robotics and Cybernetics Department of Industrial Production and Automation Jugoslávských partyzánů 1580/3 160 00 Prague Czech Republic Fraunhofer Institute for Machine Tools and Forming Technology IWU Department of Production Digital Twin Nöthnitzer Straße 44 Dresden Germany Technische Universität Dresden Institute of Mechatronic Engineering Chair of Machine Tools Development and Adaptive Controls 01062 Dresden Germany

The machining of high-value products needs advanced quality control to avoid the risk of expensive follow-up operations performed on parts with unacceptable quality. This situation requires the in-process or close to in-process control of the machining operation. The tangential cutting force is a parameter that characterizes the force interaction between the specific workpiece material and the specific tool geometry. This paper presents a method for a tangential cutting force calculation along the given tool path based on processing of the high-frequency data acquired from the machine tool control system with support of the geometric material removal model. The calculated data are compared with the reference dynamometer results. The influence of the variable engagement parameters is demonstrated and discussed from the perspective of the in-process workpiece quality control.

关键词： In-process monitoring leakage model cutting force model spindle current edge computing

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Everting of tubular net structures based on Shape Memory Alloys

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Engineering Research Express 2021年第2期3卷

作者： Hensel, Sebastian Boxberger, Lukas Weisheit, Linda Schellnock, Julia Thielsch, Juliane Riedel, Frank Drossel, Welf-Guntram Fraunhofer Institute for Machine Tools and Forming Technology IWU Dresden01187 Germany Professorship for Adaptronics and Lightweight Design Chemnitz University of Technology Chemnitz09126 Germany

Foldable technical structures can be used to provide a temporary additional volume. In nature, a tubular folding application is the extension of the snail eye. The present study uses this approach. A transformation into a technical application is only successful if the high eversion loads are considered. The study aims to develop a method to realize such structures based on a metallic wire net structure. The tube consists of Shape Memory Alloy (SMA) pieces connected by developed crimp elements produced by additive manufacturing. Additive manufacturing was used to provide a fast and effective way to make several crimp element geometries available to define a preferred variant. In a preliminary building study, the printing parameters for crimp element production were improved. The tubular structure development is assisted by numerical simulation of the eversion process. The SMA material model parameters were identified with experimental tension tests. A feasible way to connect additively manufactured crimp elements with SMA wire was found within a joining method study. Tension tests of the connections protect against pull-out failure. The eversion process was investigated using a high-speed camera system. Multiple eversion of the developed structure is possible without failure. © 2021 The Author(s). Published by IOP Publishing Ltd.

关键词： 3D printers

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Data Acquisition Framework for spatio-temporal analysis of path-based welding applications

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Procedia CIRP 2024年 130卷 1644-1652页

作者： Georgij Safronov Heiko Theisinger Vasco Sahlbach Christoph Braun Andreas Molzer Anabelle Thies Christian Schuba Majid Shirazi Thomas Reindl Albrecht Hänel Philipp Engelhardt Steffen Ihlenfeldt Peter Mayr BMW AG Petuelring 130 80788 München Germany Technical University of Munich Chair of Materials Engineering of Additive Manufacturing Freisinger Landstraße 52 85748 Garching bei München Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Nöthnitzer Straße 44 01187 Dresden Germany nebumind GmbH Willy-Messerschmitt-Straße 1 82024 Taufkirchen Germany

The use of digital technologies in industrial manufacturing reduces operational costs and improves production quality. The “Framework for Spatiotemporal Production Data Acquisition” (PathSense) aims to improve access and usability of production data by applying a common data ecosystem. Through integrating operational technology (OT) and information technology (IT), PathSense supports decision-making and process optimization. The framework uses the concept of digital shadows to collect critical information from sensors within the continuous manufacturing processes, e.g., welding or gluing lines. Spatial and temporal digital shadows are developed in accordance with human spatial cognition to support sophisticated–yet intuitive–human-computer interactions without the need for advanced data science skills. The backbone of the framework consists of robust data pipelines with a setup incorporating modern IT protocols, such as OPC UA and MQTT, to support the efficient acquisition and management of data. The paper addresses the challenges associated with the combination of IT and OT in cyber-physical systems, stressing modern complex data-intensive manufacturing as one exemplary domain to be tackled by scalable and secure data architectures. The paper identifies two major future directions: refining data integration processes and embedding advanced machine learning algorithms to enable automated data analysis and improve process quality monitoring. In summary, PathSense proposes a data-driven approach for quality inspection in manufacturing, which may eventually enhance industry practices and move towards data-driven decisions and increased operational flexibility.

关键词： PathSense digital twin welding process data acquisition spatiotemporal analysis defect detection OPC UA MQTT AI

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Characterization of vibration in continuous generating grinding and resulting influence on tooth flank topography and gear excitation

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Procedia CIRP 2021年 99卷 208-213页

作者： Jonas Böttger Simon Kimme Welf-Guntram Drossel Institute for Machine Tools and Production Processes IWP Chemnitz University of Technology Reichenhainer Str. 70 09126 Chemnitz Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 09126 Chemnitz Germany

Besides harmonic meshing frequencies, excitation behavior of gears is highly affected by micro geometry of tooth surface caused by waviness on gear flank topography. Errors in finishing processes like continuous generating gear grinding are examined to demonstrate their impact on gear flank topography under consideration of characteristic waviness with a simulation model. Results of an experimental investigation on manufactured topography and measured transmission error show well correlation with the model. The pursued analysis of characteristic cutting volume in frequency domain of systematically considered process errors is a reasonable step towards the prediction of process conditions in the manufacturing process.

关键词： Grinding Gear Vibration Simulation

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Subjective validation for short-term material flow simulation

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Procedia CIRP 2025年 134卷 562-566页

作者： Heiner Reinhardt Boran Bogdanow Roman Arnold Bastian Prell Philipp Klimant Frank Seifert Mahtab Mahdaviasl Steffen Ihlenfeldt Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Straße 88 09126 Chemnitz Germany Volkswagen Sachsen GmbH Kauffahrtei 47 09120 Chemnitz Germany Technical University of Applied Sciences Wildau Hochschulring 1 15745 Wildau Germany Professorship Virtual Technologies Hochschule Mittweida - University of Applied Sciences Technikumplatz 17 09648 Mittweida Germany Chemnitz University of Technology Straße der Nationen 62 09111 Chemnitz Germany Institute of Machine Tools and Control Engineering Technische Universität Dresden Helmholtzstraße 7a 01062 Dresden Germany

Material flow simulation, by means of discrete event simulation (DES), is frequently applied to support decision-making in production planning and control. However, manual modeling can be time-consuming and error-prone. Hence, numerous studies propose the automation of model generation and synchronization to overcome these challenges. However, in this context, validation techniques are rarely addressed. Therefore, we introduce a subjective validation technique for short-term material flow simulation based on a coherent methodology for data acquisition and visualization. The methodology is utilized to evaluate the outcome of an approach for computerized model generation and simulation. By means of an industrial use case, we hypothesize the causes for the deviation between the operation of a manufacturing system and the simulation of its generated virtual companion.

关键词： Digital Twin Simulation Quality Optimization Manufacturing system Control Analysis

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Combined laser hardening and laser surface texturing forming tool 1.2379 11

Combined laser hardening and laser surface texturing forming...

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11th CIRP Conference on Photonic Technologies, LANE 2020

作者： Aragaw, Endalkachew Mekonnen Gärtner, Eric Schubert, Andreas Institute for Machine Tools and Production Processes Chemnitz University of Technology Reichenhainer Str. 70 09107 Germany Fraunhofer Inistitute for Machine tools and Forming Technology IWU Reichenhainer Str. 88 09126 Germany

This paper deals with the tribological performance of forming tool steel 1.2379. Laser hardening and Laser surface texturing are proposed as processes to improve this tribological performance. Hardening influences the surface hardness and wear resistance. While considering the parameter and the specific material, the correlation between heating power and material property is first modelled using FEM of the heat transfer. Based on the modelling result, the realization is performed by nanosecond laser and analyzed by SEM and by comparing the micro - hardness comparison with a reference value. Then textures are integrated into the hardened surface by picosecond laser ablation while focusing on its suitability for smooth dimples and on the examination by pin-on-disk tests for the effect of incorporating textures on the friction performance. Lower friction coefficients between tool and workpiece improve tool durability and product quality as well. © 2020 The Authors. Published by Elsevier B.V.

关键词： Microhardness

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Perception of embodied digital technologies: robots and telepresence systems

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Human-Intelligent Systems Integration 2023年第1期5卷 43-62页

作者： Mandl, Sarah Brade, Jennifer Bretschneider, Maximilian Asbrock, Frank Meyer, Bertolt Jahn, Georg Klimant, Philipp Strobel, Anja Professorship of Personality Psychology and Assessment Chemnitz University of Technology Chemnitz Germany Institute for Machine Tools and Production Processes Chemnitz University of Technology Chemnitz Germany Professorship of Social Psychology Professorship of Work Organizational and Economic Psychology Chemnitz University of Technology Chemnitz Germany Professorship of Social Psychology Chemnitz University of Technology Chemnitz Germany Professorship of Work Organizational and Economic Psychology Chemnitz University of Technology Chemnitz Germany Professorship Applied Geropsychology and Cognition Chemnitz University of Technology Chemnitz Germany Professorship Virtual Technologies Hochschule Mittweida - University of Applied Sciences Mittweida Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Fraunhofer-Gesellschaft Chemnitz Germany

Embodied Digital Technologies (EDTs) are increasingly populating private and public spaces. How EDTs are perceived in Hybrid Societies requires prior consideration. However, findings on social perception of EDTs remain inconclusive. We investigated social perception and trustworthiness of robots and telepresence systems (TPS) and aimed at identifying how observers’ personality traits were associated with social perception of EDTs. To this end, we conducted two studies (N1 = 293, N2 = 305). Participants rated five different EDTs in a short video sequence of a space sharing conflict with a human in terms of anthropomorphism, sociability/morality, activity/cooperation, competence, and trustworthiness. The TPS were equipped with a tablet on which a person was visible. We found that the rudimentarily human-like TPS was perceived as more anthropomorphic than the automated guided vehicle, but no differences emerged in terms of other social dimensions. For robots, we found mixed results but overall higher ratings in terms of social dimensions for a human-like robot as opposed to a mechanical one. Trustworthiness was attributed differently to the EDTs only in Study 2, with a preference toward TPS and more human-like robots. In Study 1, we did not find any such differences. Personality traits were associated with attributions of social dimensions in Study 1, however results were not replicable and thus, associations remained ambiguous. With the present studies, we added insights on social perception of robots and provided evidence that social perception of TPS should be taken into consideration before their deployment.

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