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Characterization of material parameters for high speed forming and cutting via experiment and inverse simulation

AIP Conference Proceedings 2018年第1期1960卷

作者： Christian Scheffler Verena Psyk Maik Linnemann Marc Tulke Alexander Brosius Dirk Landgrebe 1)Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 D-09112 Chemnitz 2)Technische Universität Dresden Chair of Forming Processes FF D-01062 Dresden

High speed velocity effects in production technology provide a broad range of technological and economic advantages [1, 2]. However, exploiting them necessitates the knowledge of strain rate dependent material behavior in process modelling. In general, high speed material data characterization features several difficulties and requires sophisticated approaches in order to provide reliable material data. This paper proposes two innovative concepts with electromagnetic and pneumatic drive and an approach for material characterization in terms of strain rate dependent flow curves and parameters of failure or damage models. The test setups have been designed for investigations of strain rates up to 105 s-1. In principle, knowledge about the temporary courses and local distributions of stress and strain in the specimen is essential for identifying material characteristics, but short process times, fast changes of the measurement values, small specimen size and frequently limited accessibility of the specimen during the test hinder directly measuring these parameters at high-velocity testing. Therefore, auxiliary test parameters, which are easier to measure, are recorded and used as input data for an inverse numerical simulation that provides the desired material characteristics, e.g. the Johnson-Cook parameters, as a result. These parameters are a force equivalent strain signal on a measurement body and the displacement of the upper specimen edge.

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Surface structuring of boron doped CVD diamond by micro electrical discharge machining

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AIP Conference Proceedings 2018年第1期1960卷

作者： A. Schubert T. Berger A. Martin M. Hackert-Oschätzchen N. Treffkorn R. Kühn 1Professorship Micromanufacturing Technology Faculty of Mechanical Engineering Chemnitz University of Technology 09107 Chemnitz Germany 2Fraunhofer Institute for Machine Tools and Forming Technology 09126 Chemnitz Germany

Boron doped diamond materials, which are generated by Chemical Vapor Deposition (CVD), offer a great potential for the application on highly stressed tools, e. g. in cutting or forming processes. As a result of the CVD process rough surfaces arise, which require a finishing treatment in particular for the application in forming tools. Cutting techniques such as milling and grinding are hardly applicable for the finish machining because of the high strength of diamond. Due to its process principle of ablating material by melting and evaporating, Electrical Discharge Machining (EDM) is independent of hardness, brittleness or toughness of the workpiece material. EDM is a suitable technology for machining and structuring CVD diamond, since boron doped CVD diamond is electrically *** this study the ablation characteristics of boron doped CVD diamond by micro electrical discharge machining are investigated. Experiments were carried out to investigate the influence of different process parameters on the machining result. The impact of tool-polarity, voltage and discharge energy on the resulting erosion geometry and the tool wear was analyzed. A variation in path overlapping during the erosion of planar areas leads to different microstructures. The results show that micro EDM is a suitable technology for finishing of boron doped CVD diamond.

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State-based and Self-adapting Algorithm for Condition Monitoring

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Procedia CIRP 2017年 62卷 311-316页

作者： Matthias Putz Uwe Frieß Markus Wabner Axel Friedrich Andreas Zander Holger Schlegel Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Straße 88 09126 Chemnitz Germany Autinity Systems GmbH Neefestraße 40 09119 Chemnitz Germany UNION Werkzeugmaschinen GmbH Chemnitz Clemens-Winkler-Straße 5 09116 Chemnitz Germany Institute for Machine Tools and Production Processes Reichenhainer Straße 70 09126 Chemnitz Germany

Condition Monitoring and Maintenance prediction are permanent demands of state-of-the-art machine tools. Their IT-infrastructure including drive control systems and specific sensors deliver extensive amounts of data for monitoring. However to combine and link this data to define critical characteristic values remains challenging. The paper presents a novel approach to deal with these tasks. Firstly equal machine states are detected at different times by checking and comparing several parameters. If an equal state is detected an algorithm is executed which leads to a characteristic value. The value as well as its limits is self-adapting and time-depending by constant redefining based on the machine history.

关键词： Condition monitoring Algorithm Maintenance Self-adapting Characteristic value machine state

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Process Design for Hybrid Sheet Metal Components

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Acta Metallurgica Sinica(English Letters) 2015年第12期28卷 1518-1524页

作者： Rico Haase Roland Müller Dirk Landgrebe Peter Scholz Matthias Riemer Fraunhofer Institute for Machine Tools and Forming Technology IWU

The global trends towards improving fuel efficiency and reducing CO;emissions are the key drivers for lightweight solutions. In sheet metal processing, this can be achieved by the use of materials with a supreme strength-toweight and stiffness-to-weight ratio. Besides monolithic materials such as high-strength or light metals, in particular metal–plastic composite sheets are able to provide outstanding mechanical properties. Thus, the adaption of conventional, wellestablished forming methods for the processing of hybrid sheet metals is a current challenge for the sheet metal working industry. In this work, the planning phase for a conventional sheet metal forming process is studied aiming at the forming of metal–plastic composite sheets. The single process steps like material characterization, FE analysis, tool design and development of robust process parameters are studied in detail and adapted to the specific properties of metal–plastic composites. In material characterization, the model of the hybrid laminate needs to represent not only the mechanical properties of the individual combined materials, but also needs to reflect the behaviour of the interface zone between *** on experience, there is a strong dependency on temperature as well as strain rate. While monolithic materials show a moderate anisotropic behaviour, loads on laminates in different directions generate different strain states and completely different failure modes. During the FE analysis, thermo-mechanic and thermo-dynamic effects influence the temperature distribution within tool and work pieces and subsequently the forming behaviour. During try out and production phase,those additional influencing factors are limiting the process window even more and therefore need to be considered for the design of a robust forming process. A roadmap for sheet metal forming adjusted to metal–plastic composites is presented in this paper.

关键词： Characterization Hybrids Interface Layered structures Processing Sheet forming

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A Production Planning Method to Optimally Exploit the Potential of Reconfigurable Manufacturing Systems

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Procedia CIRP 2017年 62卷 181-186页

作者： Andreas Hees Christina Bayerl Brian Van Vuuren Corné S.L. Schutte Stefan Braunreuther Gunther Reinhart Fraunhofer Institute for Machine Tools and Forming Technology (IWU) Project Group Resource-efficient Mechatronic Processing Machines Beim Glaspalast 5 86153 Augsburg Germany Stellenbosch University Department of Industrial Engineering Private Bag X1 Stellenbosch 7602 South Africa

Manufacturing companies must operate in a dynamic environment. Consequently, companies constantly have to adapt their manufacturing systems to stay competitive. One approach to ensure the success of manufacturing companies is to use reconfigurable manufacturing systems (RMS). Current production planning methods cannot quickly realize the production-side adaptions available in RMS and are limited in flexibility. A novel production planning method to optimize the potential of RMS is presented in this paper. First, the key characteristics and planning requirements for an RMS are defined. A feasible configuration is then determined, using a planning method based on mixed integer linear programming (MILP) to realize capacity scalability and functionality changes within planning processes. Finally, an application scenario to validate the method is outlined.

关键词： Production planning Reconfiguration Scheduling

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Efficient Quantification of Free and Forced Convection

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PAMM 2018年第1期18卷

作者： Janine Glänzel Martin Stoll Roman Unger Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Straße 88 09126 Chemnitz Germany Technische Universität Chemnitz Faculty of Mathematics Reichenhainer Straße 41 09126 Chemnitz Germany

Thermo-elastic deformations represent one of the main reasons for positioning errors in machine tools. Investigations of the thermo-mechanical behaviour of machine tools often rely on accurate simulations involving large-scale CFD simulations, where the heat transfer coefficient is computed. It has been shown that radial basis functions (RBFs) are a valid tool to reduce the number of CFD simulations by interpolation. We here present an efficient approach for the case of a three-axis milling machine.

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Energy storage in drive systems of servo presses for reduction of peak power and energy recovery

Energy storage in drive systems of servo presses for reducti...

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European Conference on Power Electronics and Applications

作者： Matthias Putz Peter Blau Artem Kolesnikov Mark Richter Alexander Pierer FRAUNHOFER INSTITUTE FOR MACHINE TOOLS AND FORMING TECHNOLOGY

ISBN: (纸本)9781509014101

The development approach for energy storage systems focuses on optimally sized capacitor modules to reduce peak power and to avoid energy recovery of production machines. Using servo presses as an example, the application of two different energy storage systems in the DC link is practically examined. A simulation model in Matlab/Simulink and a test stand of a servo press are proposed for representing the power flows between the mains supply, the electric drives and the storage systems. The description of forming machines and the behaviour of the electric components are used to control the amount of stored energy in a storage system and to influence the process regarding a reduction of peak power.

关键词： Efficiency Energy Storage Supercapacitor Servo-drive Peak Shaving

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On the development of a finite element model to analyze the behavior of hybrid composites considering the manufacturing history

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IOP Conference Series: Materials Science and Engineering 2018年第1期418卷

作者： M Riemer R Kießling R Müller W-G Drossel D Landgrebe J Ihlemann Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Straße 88 09126 Chemnitz Germany Chair of Solid Mechanics Faculty of Mechanical Engineering Chemnitz University of Technology Reichenhainer Straße 70 09126 Chemnitz Germany

Hybrid parts are strongly moving into the focus for lightweight applications. Unfortunately, the accurate, simulative design, which comprises the accurate prediction of final part geometry, is still a challenging task. In the scope of this paper, an approach to improve the accuracy of appropriate finite element simulations is presented. To this end, the manufacturing history of the hybrid part is considered within the simulation of the part behavior. To create a finite element model of the considered hybrid composite, the intrinsic manufacturing process is modelled first. This includes the modelling of the thermoforming process of a fiber reinforced polymer as well as the sheet metal forming process for the fabrication of form fit elements. Then, the geometry of the hybrid part is deduced from the geometries of the single components. Afterwards, the material properties, including the local fiber volume content as well as the local fiber orientation, are mapped to the finite elements. Consequently, a workflow to create a finite element model which considers manufacturing history is developed and successfully tested.

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Transmission Acoustics Between End-of-Line Testing and Vehicle Rating

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ATZextra worldwide 2016年第1期21卷 6-9页

作者： Knöfel, Björn Troge, Jan Drossel, Welf-Guntram Fraunhofer Institute for Machine Tools and Forming Technology IWU Chemnitz Germany

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Decoupling of Fluid and Thermo-elastic Simulations on machine tools Using Characteristic Diagrams

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Procedia CIRP 2017年 62卷 340-345页

作者： Janine Glänzel Steffen Ihlenfeldt C. Christian Naumann Matthias Putz Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Straße 88 09126 Chemnitz Germany Technische Universität Dresden Helmholtzstraße 7a 01069 Dresden Germany Technische Universität Chemnitz Reichenhainer Straße 70 09126 Chemnitz Germany

Thermo-elastic effects are one of the major reasons for positioning errors in machine tools. Next to friction and waste heat from drives, the heat exchange with the machine's surroundings influences the temperature field inside the machine tool significantly. The thermal parameters necessary to describe this heat transfer can be obtained through computational fluid dynamics (CFD) simulations. This paper presents a new method aimed at decoupling these CFD simulations from the thermo-elastic simulations in order to provide the heat transfer parameters quickly and efficiently for transient environmental conditions. This is done by defining a suitable set of load scenarios for the CFD simulations, clustering the resulting parameters with radial basis functions and interpolating them using characteristic diagrams.

关键词： machine tool Simulation Thermal effects Characteristic diagrams Radial basis functions

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