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Incremental sheet metal forming on the example of car exterior skin parts

Procedia Manufacturing 2019年 29卷 105-111页

作者： Sören Scheffler Alexander Pierer Peter Scholz Sebastian Melzer Dieter Weise Zdeněk Rambousek Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Straße 88 09126 Chemnitz Germany VÚTS a.s. Svárovská 619 Liberec XI-Růžodol I 460 01 Liberec Czech Republic

In this article, current, application-related investigations in the field of incremental sheet metal forming (ISF) will be presented and discussed. The main focus of the study will be on the chain of conceptual design, experimentation and subsequent work processes, right through to the final assembly of car exterior skin parts of a streamlined vintage concept car. This will be accompanied by a comparison and evaluation of different production technologies with regard to their economic efficiency, their real duration times and the specific boundary conditions for the manufacturing of just one part per geometry. The manufacturing processes at the centre of the study were: deep drawing, hydroforming and ISF (Two Point Incremental forming (TPIF) and rolling). Following the holistic discussion on the procedure and choice of processes, the TPIF is examined in detail using the example of the rear mudguards.

关键词： Incremental Sheet Metal forming Two Point Incremental forming Sheet Metal forming forming machine Design

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Wishbone made of hybrid aluminum foam sandwich

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Lightweight Design worldwide 2018年第2期11卷 36-41页

作者： Claudia Drebenstedt Camilo Zopp Alexander Hackert Lothar Kroll Fraunhofer Institute for Machine Tools and Forming Technology IWU Chemnitz Germany TU Chemnitz Germany

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Structural loading of cellular metals: Damage mechanisms and standardization concepts 10th

Structural loading of cellular metals: Damage mechanisms and...

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10th International Conference on Porous Metals and Metallic Foams, MetFoam 2017

作者： Krupp, Ulrich Hipke, Thomas Nesic, Srecko Institute of Materials Design and Structural Integrity University of Applied Sciences Osnabrück Osnabrück49009 Germany Fraunhofer Institute of Machine Tools and Forming Technology IWU Chemnitz09126 Germany

ISBN: (纸本)9783035712315

Structural loading of cellular metals is strongly affected by brittle fracture of cell struts and walls that exhibit tensile loads, e.g., during fatigue loading. The present paper summarizes results of compression, tension and cyclic loading experiments on various closed-cell metal foams and metal foam sandwiches (Alulight, Alporas, Foamtech, AFS) using various mechanical testing systems. The results were correlated with a thorough analysis of the cellular mesostructure and the cell strut/wall microstructure by means of scanning electron microscopy revealing defects, such as casting porosity and large Si precipitates in the Al-Si eutectic of aluminum cast alloy. The results of the work served for the definition of testing standards for compression testing (ISO 13314) and tensile testing (DIN 50099), which are outlined in the paper. Such standards and design guidelines are crucial for a successful implementation of cellular metals in innovative products in mechanical, automotive and energy engineering as well as in bioengineering. © 2018 Trans Tech Publications, Switzerland.

关键词： Tensile testing

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Decision Support for Planning Techniques in Energy Efficiency Projects

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Procedia CIRP 2018年 69卷 306-311页

作者： Marian Süße Johannes Stoldt Andreas Schlegel Matthias Putz Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Straße 88 09126 Chemnitz Germany

Factory operators can select from a multitude of measures to improve their energy efficiency. Despite the variety of planning techniques intended to help investigating the energy flows, little assistance is available for determining the most efficient approach to pursue in a specific project. This paper presents decision support procedures for making appropriate selections during planning, focusing on the selections of an energy model and a matching energy data acquisition method. They build on problem-independent decision models and systematize available alternatives. The models are solved independently by applying the Analytic Hierarchy Process that allows the integration and quantification of different criteria.

关键词： Energy efficiency Sustainable development Decision-making Analytic Hierarchy Process

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Methodology and model for predicting energy consumption in manufacturing at multiple scales

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Procedia Manufacturing 2018年 21卷 694-701页

作者： Jan Reimann Ken Wenzel Marko Friedemann Matthias Putz Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Straße 88 09126 Chemnitz Germany

Certain fields of manufacturing, like casting, forming or cutting, may cause high energy load. Especially under the consideration of renewable energy sources it is beneficial to negotiate production schedules and consumption forecasts with the energy supplier. This would enable an optimized management of energy sources and infrastructure components on the supplier side, helping to reduce costs. Optimal and balanced expenses for production would be the consequence. The problem of power consumption prediction in manufacturing was subject of many studies in the past. Most of them either consider the physical modeling of processes at a very detailed level, or they introduce tailored prediction models for specific production processes. Thus, it is hard to apply their results to other uses cases in different scenarios. As a consequence, a generic methodology and model regarding power consumption prediction in manufacturing is required in order to cover the variety of processes, machines and materials. Furthermore, an approach must support flexible levels of granularity for predicting the energy consumption of manufacturing processes. On the one hand, a whole factory may be the object of investigation while, on the other hand, predictions for finer-grained levels, such as certain parts of a machine, are required to allow for specific optimizations. Our contribution is twofold. First, we propose a generic model for the specification of the power-consuming machine. A tree-based compositional approach supports arbitrary levels, depending on the structure of the machine, or external factors, such as company policies. This approach is highly extensible since the models are stored in ontologies. Second, we propose a methodology for static and dynamic modeling of power consumption for every structural level. Based on that model the prediction can be realized. In addition, we provide an example implementation and prediction for a continuous casting machine process.

关键词： Energy efficiency Predictive Model Ontology

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Product Flexible Car Body Fixtures with Position-dependent Load Balancing Based on Finite Element Method in Combination with Methods of Artificial Intelligence

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Procedia CIRP 2018年 67卷 452-457页

作者： Rayk Fritzsche Andreas Richter Matthias Putz Head of group assembly systems at Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Strae 88 Chemnitz 09126 Germany Scientific employee at Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Strae 88 Chemnitz 09126 Germany

In car-body production, the fixtures used for fixing the car-body panels during the joining processes predominantly consist of rigid constructions that are precise and specific for one car-model. In addition to the already presented automatic adaptation of such fixtures, and specific for the production of many different car-models using same fixture, different clamping robots have been developed. In order to meet the high quality requirements, the positional deviations of these clamping robots are adjusted due to different external loads. This control loop is carried out using a combination of finite element method, mathematical algorithms and modern methods of artificial intelligence.

关键词： Quality management Body in white Rramp up Artificial intelligence Neuronal network Database

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Process-oriented Flow Curve Determination at Mechanical Joining

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Procedia Manufacturing 2020年 47卷 368-374页

作者： Mathias Jäckel Sam Coppieters Nelis Vandermeiren Christian Kraus Welf-Guntram Drossel Noa Miyake Toshihiko Kuwabara Klaus Unruh Heinrich Traphöner A. Erman Tekkaya Tudor Balan Fraunhofer Institute for Machine Tools and Forming Technology IWU Nöthnitzer Straße 44 Dresden 01187 Germany KU Leuven Technology Campus Ghent Department of Materials Engineering Gebroeders De Smetstraat 1 Ghent 9000 Belgium Belgium Welding Institute Technologiepark 48 Ghent 9052 Belgium Institute of Engineering Tokyo University of Agriculture and Technology 3 Chome-8-1 Harumicho Tokyo 183-8538 Japan Faurecia Autositze GmbH Nordsehler Straße 38 Stadthagen 31655 Germany Institute of Forming Technology and Lightweight Components TU Dortmund Baroper Straße 303 Dortmund 44227 Germany Arts et Metiers Institute of Technology Université de Lorraine LCFC HESAM Université F-57070 Metz France

The accuracy of numerical simulation models for forming processes depends highly on the method for the flow curve determination. Numerous experimental tests exist to identify the flow curves of sheet metals, each with certain characteristics regarding stress states and achievable strains. In this paper stress state analysis are presented for the mechanical joining techniques clinching as well as self-pierce riveting with semi-tubular rivet (SPR). Based on these findings flow curves for DC04 material are determined by selected experimental materials tests in order to compare the influence of the flow curve determination method on the accuracy of the process simulation models.

关键词： Mechanical Joining Material Chracterization Numerical Simulation

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Modified Cross-Wedge Rolling for Creating Hollow Shafts

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Procedia Manufacturing 2018年 21卷 53-59页

作者： Dirk Landgrebe Jürgen Steger Uwe Böhmichen Markus Bergmann Fraunhofer Institute for Machine Tools and Forming Technology (IWU) Reichenhainer Str. 88 09126 Chemnitz Germany

Cross-wedge rolling (CWR) is an incremental forming method for producing rotationally symmetric components such as a basic shape of gear shaft or a preform before impression die forging. In CWR the material of a solid cylindrical billet is redistributed in axial direction while the billet diameter is reduced. Conventional CWR cannot be used to produce hollow shapes. This paper presents a modified CWR process, which enables the manufacturing of hollow shafts and thus provides a technological base for utilizing the large potential of the method regarding cost and resource efficiency in mass production. The method introduces two mandrels which act concurrently with the tooling wedges in an elaborate kinematic system. During processing, the generated shear stresses induce fracturing located along the billet axis. The actively driven mandrels use the fracture and penetrate axially into the workpiece. This paper provides a description of the basic principle of this innovative method and discusses the complex interaction between tool geometries, kinematic system and processing parameters.

关键词： Production Process Hot Forging Cross-wedge Rolling Tubing Billet Preforming

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Enhancement and analysis of multidimensional characteristic diagrams for correction of TCP-displacements caused by thermal tool displacement

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Procedia CIRP 2018年 77卷 553-556页

作者： Matthias Putz Christian Oppermann Michael Bräunig Fraunhofer-Institute for Machine Tools and Forming Technology IWU 09126 Chemnitz Germany Chemnitz University of Technology 09010 Chemnitz Germany

In the present paper former developed characteristic diagram approaches for the correction of thermo-elastic TCP-displacements during cutting processes are extended. Input variables linked with the resulting deformations are estimated by Design of Experiments (DoE). Deformations are computed by means of FEA via the estimation of heat fluxes in the system workpiece – chip – tool – clamping device and the temperature field in tool and clamping device. Multidimensional characteristic diagrams are derived to enable real-time correction of tool paths within the machine tool control. These correction approaches are of crucial importance especially in the field of precision machining and difficult-to-cut material generating large heat amounts. With the obtained correction values the effect of the different cutting parameters on the TCP-displacement is investigated in a sensitivity analysis.

关键词： TCP-displacement Thermal error Characteristic diagramm machine Tool Sensitivity analysis Design of Experiments

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Verification of a novel measuring method for determining pre- and postoperative leg length in the context of total hip arthroplasty: a technical feasibility study

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Journal of Medical Engineering and technology 2018年第8期42卷 588-594页

作者： Schmidt, Michael Prietzel, Torsten Wendler, Toni Möbius, Robert Schleifenbaum, Stefan Hammer, Niels Grunert, Ronny ZESBO - Center for Research on Musculoskeletal Systems University of Leipzig Leipzig Germany Department of Orthopaedic Trauma and Plastic Surgery University of Leipzig Leipzig Germany Department of Orthopaedic and Trauma Surgery HELIOS Clinic Blankenhain Blankenhain Germany Department of Anatomy University of Otago Dunedin New Zealand Fraunhofer Institute for Machine Tools and Forming Technology Fraunhofer IWU Dresden Germany

Following total hip arthroplasty (THA), leg length can easily be modified, for example by different-sized endoprosthetic components. Currently, precise reconstruction depends mainly on the assessment of the surgeon. The aim of this study was to determine the accuracy of a new optical measuring system (OMS) using a novel measuring method capable of determining changes in leg length. Measurements with different investigators on an artificial leg and under clinical conditions were carried out. Measurements under clinical conditions were accomplished with a human body donor before and following prosthetic hip implantation. Furthermore, computed tomography (CT) was used to compare the function and the precision of the OMS relating to established measuring methods. The following results were achieved. The overall mean result of preoperative leg length determination by the OMS was 775.3 ± 5.8 mm (CT: 786.4 mm). The overall mean result of postoperative leg length determination by the OMS was 776.9 ± 10.8 mm (CT: 795.0mm). Measurements carried out showed that the novel measuring method works in principle. However, the viable prototype based on it has a lower accuracy compared to CT-based reference measurements, indicating the necessity of integrating more precise hardware. © 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group.

关键词： Arthroplasty

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