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Analysis of biobased cooling lubricants in milling stainless steel for aerospace applications – A study of tribology and performance

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Procedia CIRP 2024年 125卷 113-118页

作者： Erik Selbmann Johanna Sophie Hagen Albrecht Hänel Anas Ben Achour Uwe Teicher Christoph Herrmann Steffen Ihlenfeldt Fraunhofer Institute for Machine Tools and Forming Technology IWU 01187 Dresden Germany Fraunhofer Instiute for Surface Engineering and Thin Films IST 38108 Braunschweig Germany TU Braunschweig Institute for Machine Tools and Process Technology 38106 Braunschweig Germany TU Dresden Institute of Mechatronic Engineering 01062 Dresden Germany

Due to high thermomechanical loads, metal cutting processes generally require cooling and lubrication solutions to minimize friction between tool and workpiece. Nowadays, the standard in industry is the application of mineral-oil-based coolants, which represent a significant share of the CO 2 -footprint in production systems in terms of their extraction, fabrication and disposal. The demand for ecological innovations pushes the manufacturing sector to apply sustainable and health compatible coolant alternatives based on renewable vegetable oils for safer work environments and greener production systems. In this work, both mineral-oil-based cooling lubricants and several water-miscible emulsions based on vegetable oils were prepared and tested regarding their suitability for milling tasks of aircraft stainless steels. Therefore, comprehensive tribological investigations were carried out to determine the friction conditions in the contact zone between the tool cutting edge and the workpiece. Additionally, extensive experimental investigations were carried out to measure the process forces and the resulting tool wear as technical performance indicators of the cooling lubricants during machining. The study shows the significant potential of bio-based cooling lubricants as high-performance alternatives to conventional cooling lubricants when milling aircraft stainless steels, regarding the improvement of the tribological system of machining processes and the work environment.

关键词： Bio-based cooling lubricants tribology friction process forces tool wear

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AI-driven force torque control strategies for further automate flexible high-precision, contact-intensive assemblies

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Procedia CIRP 2024年 130卷 348-354页

作者： Yunqi Gu Ruth Maria Otto Martin Naumann Leutrim Gjakova Rico Löser Martin Dix University of Applied Sciences Munich Lothstr. 34 80335 Munich Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU 09126 Chemnitz Germany Chemnitz University of Technology 09111 Chemnitz Germany

Robotic assembly processes are integral to industrial manufacturing, traditionally relying on pre-programmed sequences that exhibit limited adaptability to uncertain conditions. Recent advancements propose AI-enhanced vision systems as viable solutions to mitigate uncertainty in automated tasks. Despite the potential of vision, contact-intensive, high-precision assembly processes need customized force-torque feedback strategies to perform the task. Parametrization for setup and adaption of force-torque processes are time consuming, but decisive for quality. This work outlines an AI-driven force-torque control strategic solution for peg-in-hole assembly task, which employs object detection algorithm to grasp the workpiece and determine flexible assembly position, with force-torque-informed DNN algorithm for error correction in terms of position, and digital twin to monitor the process and collect virtual data.

关键词： Robotic Assembly Force-torque control Deep-Neural-Network Cognitive Robotics

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Incremental micro-forming for surface finishing with piezoelectrically actuated hammering tool with coupling unit 21

Incremental micro-forming for surface finishing with piezoel...

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21st International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2021

作者： Fiedler, Maik Kolouch, Martin Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 Chemnitz09126 Germany

ISBN: (纸本)9780995775190

machine hammer peening can be referred as an incremental mechanical surface treatment procedure, which can be realized by using various tools being based on various actuator principles. For the purpose of high productivity, a high-performance drive for generating vibrations in the tool of a high frequency is desired. Therefore, this paper presents a new hammer peening tool with a piezoelectric actuator. In order to facilitate this actuator principle for practical applications, a coupling unit is necessary being installed between the tool and the machine. This coupling unit insulates the process vibration at the machine (e.g. a machine tool or an industrial robot) and changes the operating mode of the hammer peening process from position controlled to force controlled. In such way, the accuracy of the positioning movement as well as the accuracy of the workpiece are not the issue anymore and the piezoelectrically actuated tool with a low stroke of 120 µm can be deployed for practical applications. This tool together with the coupling unit can reach hammering frequencies in the range from 800 to 1300 Hz. These frequencies enable higher feed rates and productivity of the hammer peening process than tools with pneumatic or electromagnetic actuators being available on the market. For the purpose of demonstration of the tool potential, some experimental tests are presented in this paper. Here, workpiece being milled like in die making were treated by the hammer peening process with the new tool. The surface were smoothed from Ra 1.18 μm to Ra 0.10 μm. © 2021 Proceedings of the 21st International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2021. All rights reserved.

关键词： Piezoelectric actuators

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Investigations on Case Hardening of an Additive Manufactured Steel 20MnCr5 (via PBF-LB/M)

Investigations on Case Hardening of an Additive Manufactured...

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作者： Mallow, S. Schmitt, M. Gebauer, M. Stockburger, R. Reich, M. Kessler, O. Materials Science University of Rostock Albert-Einstein-Straße 2 Rostock18059 Germany Fraunhofer Institute for Casting Composite and Processing Technology Igcv Augsburg Germany Fraunhofer Institute for Machine Tools and Forming Technology Iwu Dresden Germany Hanomag Härtol Lohnhärterei GmbH Gommern Germany

As an additive manufacturing process, powder bed fusion of metals using a laser beam (PBF-LB/M) enables the near-net-shape production of complex components in a single step. In combination with case hardening, it will thus be possible in the future to produce lightweight, functionally integrated transmission components characterized by high-strength surface layers with a sufficiently tough component core. However, the process-related new initial conditions resulting from very high solidification rates in PBF-LB/M may mean that case hardening of PBF-LB/M materials with standard parameters achieves different case hardening results than have been usual in the past. This hypothesis was investigated in the present work using the case hardening steel 20MnCr5 (material number 1.7147) after successful development of industry-relevant PBF-LB/M parameters. Besides the convincing results regarding microstructure, hardness and carbon depth profiles, case hardening with standard parameters led to irregular grain growth due to holding at high temperatures for several hours during carburization. © 2023 Walter de Gruyter GmbH, Berlin/Boston, Germany.

关键词： 3D printing

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Innovative actuating process for machining CFRP with force-controlled radial feed movement

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Procedia CIRP 2023年 119卷 669-674页

作者： Marie Peter Konstantin Sauer Joachim Regel Martin Dix Institute for Machine Tools and Production Processes 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

The use of lightweight materials such as carbon fibre reinforced plastics (CFRP) is increasing due to the demand for rising resource and energy efficiency, especially in the aerospace and automotive industries. Because of the high delamination tendency of these materials and their abrasive impact on the tool, the challenges in machining CFRP lie primarily in the drilling process and thus in the design of the drilling tool. In this paper, an innovative design of a drilling tool for machining CFRP with force-controlled radial feed movement of the cutting edges is presented. The aim of this tool is to create a tool axial force free process that uses a force-controlled radial feed motion, which matches the chip cross-section to the wear condition of the cutting edge. The tool concept is explained based on the functionality of the actuating process. Tests were evaluated with regard to process forces and drilling quality to show that the tool is capable of producing delamination-free bores in a tool axial force free process.

关键词： tool design adaptive control actuator drilling composite

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Experimental validation of characteristic diagram-parameterization for environment-induced thermal interactions on machine tools in a climate chamber 14

Experimental validation of characteristic diagram-parameteri...

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14th CIRP Conference on Intelligent Computation in Manufacturing Engineering, CIRP ICME 2020

作者： Kumar, Tharun Suresh Glänzel, Janine Tehel, Robert Putz, Matthias Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 Chemnitz09126 Germany

Thermal gradients created by environmental influences on machine tools cause considerable non-linear thermo-elastic deformations whether the machine is in operation or in idle mode. When a machine tool is subjected to changes in environmental influences such as ambient air temperature, velocity or direction, then flow (CFD) simulations are necessary to effectively quantify the thermal behavior between the machine tool surface and the surrounding air. The conventional two-step simulation procedure consisting of coupled CFD and thermo-elastic simulation is highly time-consuming especially when complex geometries are considered. Decoupling of CFD and thermo-elastic simulation can be achieved by introducing a Clustering Algorithm (CA) and Characteristic Diagrams (CDs) within the simulation workflow. Using training data obtained from a limited number of CFD simulations, the CDs can predict the heat transfer coefficients (HTCs) based on the parameterized environmental influences. This paper attempts to validate the experimental temperature and displacement readings obtained at selected positions on a machine tool using a wide range of metrological equipment such thermography camera, temperature and displacement sensors with the decoupling approach based on parameterized CDs. For investigation, the machine tool is positioned in a climate chamber, which facilitates the variation of environmental influences such as ambient temperature, flow velocity and flow direction. Initially, a precise coupled simulation model is created which is later on converted to a decoupled system using parameterized CDs. © 2021 The Authors. Published by Elsevier B.V.

关键词： machine tools

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Acoustic process monitoring for ultrasonic-assisted deep drilling 27

Acoustic process monitoring for ultrasonic-assisted deep dri...

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27th International Congress on Sound and Vibration, ICSV 2021

作者： Georgi, Oliver Rüger, Carlo Rentzsch, Hendrik Hochmuth, Carsten Putz, Matthias Dix, Martin Papsdorf, Gunther Fraunhofer Institute for Machine Tools and Forming Technology IWU Chemnitz Germany SINUS Messtechnik GmbH Leipzig Germany

ISBN: (纸本)9788378807995

Regarding deep drilling, problems in terms of chip formation and removal, burrs, tool vibrations as well as process reliability occur. Modern scientific approaches face these problems and aim to improve productivity, quality and reliability to reduce manufacturing costs. At the same time, there is a trend to use in-process monitoring and control in terms of adaptive machining processes in order to operate cutting processes close to the limits of stability. The application of ultrasonic assistance for drilling and deep drilling processes enables multiple advantages like reduced tool wear and burr formation as well as enhanced chip breaking behaviour. Moreover, ultrasound enables the use of previously unused physical effects to obtain information from the process zone and identify process conditions. In this context, the paper presents an approach of using modulation phenomena to evaluate dynamic process stability, using ultrasound as a carrier signal for low-frequency vibrations related to the deep drilling tool. In addition, the resonant coupling of ultrasonic system and cutting operation is used to draw direct conclusions about the load behaviour of the machining process from characteristics of the resonant vibration system. This directly leads to the possibility to perform in-process monitoring of tool wear. The article covers the theoretical basics, the hardware realization as well as experimental investigations regarding acoustic process monitoring for ultrasonic-assisted deep drilling. © "Advances in Acoustics, Noise and Vibration - 2021" Proceedings of the 27th International Congress on Sound and Vibration, ICSV 2021. All rights reserved.

关键词： Process monitoring

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Generative design in factory layout planning 14

Generative design in factory layout planning

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14th CIRP Conference on Intelligent Computation in Manufacturing Engineering, CIRP ICME 2020

作者： Süße, Marian Putz, Matthias Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Straße 88 Chemnitz09126 Germany

Planning and optimization of facility layouts have been investigated for decades and manifold approaches are applied for structuring and design of production layouts. However, results heavily depend on the experience and creativity of involved planning experts. Currently, complexity of planning processes constantly increases, e.g. due to further requirements of energy and media supply. Generative Design, hitherto mainly applied in component development, provides opportunities to cope with a much larger solution space and develop creative layout concepts. Thus, based on a structured overview on established planning methods, a concept and first results of factory layout planning with Generative Design are described. © 2021 The Authors. Published by Elsevier B.V.

关键词： Plant layout

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Software assisted clamping point classification and position optimization for the efficient flexibilization of carbody fixtures using mathematical geometry-based search algorithms 14

Software assisted clamping point classification and position...

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14th CIRP Conference on Intelligent Computation in Manufacturing Engineering, CIRP ICME 2020

作者： Fritzsche, Rayk Schaffrath, Robert Todtermuschke, Marcel Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Straße 88 Chemnitz09126 Germany

The fraunhofer iwu has been developed specialized clamping robots for production of different car-models on one fixture. One of the challenges with universal clamping of different components is the contact point between part and clamping device. For the optimization of the clamping contours, a software was developed with which the geometries of the clamping points can be automatically analyzed and classified. With target search criteria, the clamping position on the component can be changed so that the clamping contours are geometrically simplified. Thus, a huge reduction in the complexity of the flexible clamping device is possible. © 2021 The Authors. Published by Elsevier B.V.

关键词： Product design

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Ultrasonic assistance to reduce and monitor tool wear in deep drilling 21

Ultrasonic assistance to reduce and monitor tool wear in dee...

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21st International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2021

作者： Georgi, Oliver Rüger, Carlo Rentzsch, Hendrik Putz, Matthias Dix, Martin Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 Chemnitz09126 Germany

ISBN: (纸本)9780995775190

In deep drilling, the large aspect ratio of hole depth to diameter causes problems in terms of chip formation and removal as well as tool vibrations. In addition, tool wear leads to a deterioration of process properties and decreasing process reliability. Therefore, scientific approaches aim to improve productivity and quality via a reduction of tool wear. Furthermore, methods for monitoring process conditions, specifically known as tool condition monitoring, contribute to an increase in performance. Superimposing ultrasonic vibrations to the conventional process is known as an approach with various potentials like reduced tool wear and burr formation or enhanced chip breaking behaviour. Aiming to realize in-process measurements to identify tool conditions, ultrasonic assistance enables the application of new monitoring techniques. In this context, the paper introduces a new approach to monitor tool wear using characteristic values of the resonant ultrasonic system coupled with the machining process. Experimental investigations considering deep drilling in steel 1.2311 show prove of the positive influence of ultrasonic assistance on the progress of tool wear. Furthermore, in-process measurements demonstrate that the new approach is able to monitor tool wear. © 2021 Proceedings of the 21st International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2021. All rights reserved.

关键词： Aspect ratio

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