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18th International ESAFORM Conference on Material forming, ESAFORM 2015

作者： Landgrebe, D. Mayer, B. Niese, S. Fricke, H. Neumann, I. Ahnert, M. Falk, T. Fraunhofer Institute for Machine Tools and Forming Technology IWU Nöthnitzer Straße 44 Dresden01189 Germany Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM Wiener Straße 12 Bremen28359 Germany

ISBN: (纸本)9783038354710

In multi-material-design, e.g. in the automotive industry, mechanical joining processes like self-pierce riveting are well established, because of their amount of advantages. However, adhesive bonding with one-component structural adhesives is increasingly being used. The combination of the specific advantages of both joining techniques in the form of hybrid joints leads to synergies of quality and reliability, such as high corrosion resistance and better damping properties. A critical issue is the generation of global deformations of the different parts of the mechanical joints. These global deformations of the sheet metal between two or more mechanical connectors (e.g. rivets) are caused by the formation of adhesive bags during the riveting process, before the adhesive curing takes place. This research focuses on the time-dependent formation process of these bags. The aim is to achieve a reduction of global deformations based on detailed knowledge of the adhesive flow during the manufacturing of the joint by means of experiments and simulations. For this purpose experimental techniques and measurement methods for deformations over time are presented for different setups of hybrid joint types of self-piercing rivets in combination with adhesive bonding. The challenge is to track rapid and small surface deformations very accurately in the ongoing mechanical joining process. High-speed optical measurement technology like Point-Tracking and surface scanning are used to track the resulting deformations experimentally. Numerical investigations, which include the interaction of the solid matter influenced in the mechanical joining process and the fluid adhesive, are presented. On the basis a fully coupled fluid-structure interaction simulation of a single hybrid joint, a surrogate model for a multi-point hybrid joint is developed. The comparison of experimental data with simulations allows deriving the pressure distribution and flow velocities inside the adhesive layer.

关键词： Automotive industry

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Formability enhancement in incremental forming for an automotive aluminium alloy using laser assisted incremental forming

Formability enhancement in incremental forming for an automo...

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16th International Conference on Sheet Metal, SheMet 2015

作者： Mohammadi, Amirahmad Vanhove, Hans Van Bael, Albert Weise, Dieter Duflou, Joost R. KU Leuven Department of Mechanical Engineering Belgium KU Leuven Department of Materials Engineering Belgium Fraunhofer-Institut for Machine Tools and Forming Technology IWU Department Sheet Metal Processing and Basics Chemnitz Germany

ISBN: (纸本)9783038354505

The aim of this study is to establish general guidelines for minimizing the number of tests required to determine optimum process parameters in terms of formability for laser assisted single point incremental forming (LASPIF). An automotive aluminium alloy (AA5182-O) is selected and the room temperature failure angle of this material is determined experimentally. The straining behaviour as well as sheet thinning of the test part (at its maximum forming angle) is studied using an experimentally validated finite element model. From the thinning rate of the sheet metal and the shape of the contact zone between tool and sheet it is concluded that continuous straining of the sheet on the wall region of the contact area is responsible for extra thinning and failure. Based on the size and position of the contact zone, different laser tool positioning strategies have been used to achieve the highest forming angle. It is concluded that due to an elongated shape of the contact zone in steep wall angle parts and considering a small deviation of the forming robot, the selection of a large spot diameter is necessary in terms of maximum obtainable wall angle. It has been observed that the maximum forming angle is still achievable using a large forward offset. It is concluded that the partial stress-relief annealing of the deformed geometry during the approach of the forming tool, is responsible for this formability enhancement. © 2015 Trans Tech Publications, Switzerland.

关键词： Finite element method

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Approaches for mechanical joining of 7xxx series aluminum alloys

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AIP Conference Proceedings 2016年第1期1769卷

作者： M. Jäckel T. Grimm D. Landgrebe 1Fraunhofer Institute for Machine Tools and Forming Technology IWU Nöthnitzer Straße 44 01187 Dresden Germany

This paper shows a numerical and experimental analysis of the different problems occurring during or after the conventional self-pierce riveting with semi-tubular and solid rivets of the high strength aluminum alloy EN AW-7021 T4. Furthermore this paper describes different pre-process methods by which the fracture in the high strength aluminum, caused by the self-pierce riveting processes, can be prevented and proper joining results are achieved. On this basis, the different approaches are compared regarding joint strength.

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Optical micro-metrology of structured surfaces micro-machined by jet-ECM 15

Optical micro-metrology of structured surfaces micro-machine...

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15th International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2015

作者： Quagliotti, Danilo Tosello, Guido Islam, Aminul M. Hansen, Hans N. Zeidler, Henning Martin, André Schubert, Andreas Brandao, Carla Riemer, Oltmann Technical University of Denmark Department of Manufacturing Engineering Kgs. Lyngby2800 Denmark Chemnitz University of Technology Faculty Mechanical Engineering Institute for Machine Tools and Production Processes Chemnitz09107 Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Chemnitz09126 Germany University of Bremen Laboratory for Precision Machining Bremen28359 Germany

ISBN: (纸本)9780956679079

A procedure for statistical analysis and uncertainty evaluation is presented with regards to measurements of step height and surface texture. Measurements have been performed with a focus-variation microscope over jet electrochemical micro-machined surfaces. Traceability has been achieved using as reference contact measurements from a calibrated stylus instrument. A statistical analysis has been carried out and the method of least squares has been implemented to correct for systematic behaviours. The combined uncertainty has been evaluated accordingly and the expanded uncertainty has been finally calculated as the confidence interval of 95 %. Results show that agreement within single digit micrometre (dimensional measurements) and tenths of micrometre (surface parameters measurements) can be achieved with the proposed methodology.

关键词： Least squares approximations

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The effect of cushion-ram pulsation on hot stamping

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AIP Conference Proceedings 2016年第1期1769卷

作者： Dirk Landgrebe Anja Rautenstrauch Andreas Kunke Stefan Polster Sebastian Kriechenbauer Reinhard Mauermann 1Technische Universität Chemnitz Professorship for Forming and Joining Germany 2Fraunhofer Institute for Machine Tools and Forming Technology IWU Chemnitz Germany

Hot stamping is an important technology for manufacturing high-strength components. This technology offers the possibility to achieve significant weight reductions. In this study, cushion-ram pulsation (CRP), a new technology for hot stamping on servo-screw presses, was investigated and applied for hot stamping. Compared to a conventional process, the tests yielded a significantly higher drawing depth. In this paper, the CRP technology and the first test results with hot stamping were described in comparison to the conventional process.

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Approach for Production Planning in Reconfigurable Manufacturing Systems

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Procedia CIRP 2015年 33卷 70-75页

作者： Andreas Hees Gunther Reinhart Fraunhofer Institute for Machine Tools and Forming Technology (IWU) Project Group Resource-efficient Mechatronic Processing Machines Beim Glaspalast 5 86153 Augsburg Germany

To stay competitive and to fulfill the changing market needs, manufacturing companies have to adapt their manufacturing systems in frequent and short intervals. Hence, changeable and reconfigurable manufacturing systems (RMS) are proposed and discussed in a multitude of research publications. While production planning becomes increasingly complex in this context, it has to be reliable and quick at the same time. Therefore, the performance and flexibility of manufacturing systems depends on actual and suitable planning data with high quality and wide range. In this context, a new approach for production planning in reconfigurable manufacturing systems is exposed in this paper. Data models, a configuration management and a sequential method for the resource planning help to integrate reconfigurable manufacturing systems’ key characteristics in production planning and control (PPC). Finally a prototypical application scenario, for the evaluation and demonstration of the feasibility of the planning approach, is outlined.

关键词： Production Planning Reconfiguration Scheduling

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Intrinsic manufacture of hollow thermoplastic composite/metal structures

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AIP Conference Proceedings 2016年第1期1769卷

作者： Daniel Barfuss Raik Grützner Christian Garthaus Maik Gude Roland Müller Dirk Langrebe 1Technische Universität Dresden Institute of Lightweight Engineering and Polymer Technology Germany 2Fraunhofer-Institute for Machine Tools and Forming Technology IWU Chemnitz Germany

In contrast to common and classical joining technologies for composite/metal hybrid structures such as bonding and riveting, profile and contour joints offer a promising potential for novel lightweight hybrid structures. First and foremost, joining systems with a form closure function enable to pass very high loads into rod- and tube-shaped fibre reinforced structures and achieve high degrees of material utilization for the composite part. This paper demonstrates the theoretical and technological principals for a resource efficient design and production of highly loaded thermoplastic composite profile structures with integrated metallic load introduction elements and a multi scale form closure. The hybrid structures are produced in an integral blow moulding process in which a braided tape-preform is simultaneously consolidated and formed into the metallic load introduction element. These metallic load introduction elements are manufactured in a two-stage process of external and internal hydroforming, after forming simulations have assured process stability for consistent quality.

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Energy-sensitive control strategies for decoupled production systems

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International Journal of Sustainable Manufacturing 2014年第3期3卷 250-268页

作者： Putz, Matthias Schlegel, Andreas Stoldt, Johannes Franz, Enrico Langer, Tino Division Production Management Fraunhofer Institute for Machine Tools and Forming Technology IWU Chemnitz Germany

Rising demand for energy caused by emerging economies, decreasing oil stocks, and the intended nuclear phase-out in some industrial countries has led to new problems concerning sufficient and on time energy supply. Since availability of energy has a dramatic influence on production, energy has to be considered a process prerequisite instead of a production-related overhead topic, as usually done. Prospective considerations in MES and ERP systems will need to treat energy as a limited resource just like machine capacity and time. Hence, both products and processes will compete for energy. This paper discusses selected production control tasks, methods, and strategies for discrete part manufacturing. It aims at identifying the extent to which energy features can be implemented next to established logistic goals. Based on first research activities, new approaches were derived in order to develop tools for an energy-sensitive production control focusing on limited capacity of production resources. Copyright © 2014 Inderscience Enterprises Ltd.

关键词： Production control

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Flushing Strategies for High Performance, Efficient and Environmentally Friendly Cutting

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Procedia CIRP 2015年 26卷 361-366页

作者： P. Blau K. Busch M. Dix C. Hochmuth A. Stoll R. Wertheim Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 09126 Chemnitz Germany Technische Universität Chemnitz Institute for Machine Tools and Production Processes IWP Reichenhainer Str.70 09126 Chemnitz Germany

The rising requirements in cutting operations for higher performance and higher efficiency respecting also environmental phenomena are influencing the use of different coolants and flushing conditions. In machining difficult-to-cut materials, in particular high-temperature materials, conventional emulsion cooling is unsuitable due to the insufficient cooling effect and the energy and cost intensive equipment required. For this reason new cooling and lubricating strategies have to be developed and investigated. Using hybrid processes, mainly by superposition of various cooling strategies, offers the potential to extend the existing technological process limits of conventional cutting processes. The paper introduces theoretical, experimental and simulation results with various innovative cooling strategies, such as high-pressure cooling, cryogenic cooling and aerosol dry lubrication in grooving, turning and drilling and derives the appropriate field of application for each flushing strategy.

关键词： Cutting Coolant Flushing HPC

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Multiphysics Simulation of the Material Removal in Jet Electrochemical Machining

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Procedia CIRP 2015年 31卷 197-202页

作者： Matthias Hackert-Oschätzchen Raphael Paul Michael Kowalick André Martin Gunnar Meichsner Andreas Schubert Professorship Micromanufacturing Technology Faculty of Mechanical Engineering Technische Universität Chemnitz D-09107 Chemnitz Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Strasse 88 D-09126 Chemnitz Germany

Jet Electrochemical Machining (Jet-ECM) is a technology for quickly and flexibly generating micro structures and micro geometries in metallic parts independently from the material's hardness and without any thermal or mechanical impact [1] . In the process no tool wear occurs and the machined surface is very smooth [2] . The Jet-ECM process strongly depends on the shape of the electrolyte jet. In a previous study Hackert [3] built a numerical model with COMSOL Multiphysics based on a predefined jet shape. The simulated dissolution results of this model progressively differ from experimental results with increasing processing time. Hence, a multiphysics model which integrated fluid dynamics using the level set method for two-phase flow was created. Furthermore, in the present study the electric boundary resistance at the interface of workpiece and electrolyte is considered. According to the real Jet-ECM process the simulation is divided into two steps. In the first simulation step the jet is formed, and in the second simulation step the anodic dissolution is simulated by deforming the geometry. The dynamic behavior of the electrolyte jet could be simulated during the material removal process. So effects became visible which affect the machining results.

关键词： Jet Electrochemical Machining localized anodic dissolution continuous electrolytic free jet multiphysics simulation boundary resistance

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