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

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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Influence of Global Forced-air Warming on the Bulge Formation in Shallow Sloped SPIF Parts

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Procedia Engineering 2017年 183卷 149-154页

作者： Amirahmad Mohammadi Hans Vanhove Dieter Weise Albert Van Bael Dirk Landgrebe Joost R. Duflou KU Leuven Department of Mechanical Engineering Heverlee 3001 Belgium Fraunhofer-Institut for Machine Tools and Forming Technology IWU Department Sheet Metal Processing Chemnitz 09126 Germany KU Leuven Department of Materials Engineering Heverlee 3001 Belgium

Shallow sloped single point incrementally formed (SPIF) parts typically show undesirable geometric deviations from the designed shape due to accumulated unwanted bulging. In this study, the effect of global heating by forced-air warming on the geometric accuracy of low-angled parts with a conical geometry is investigated. A finite element (FE) model was developed to simulate the SPIF process at elevated temperatures. The simulation results show that the sheet metal is subjected to significantly higher levels of stress in cold forming condition with respect to parts formed at elevated temperatures. Due to the increase in strength caused by strain hardening, a larger area of the sheet (both in the wall and bulge regions) is affected by the tool during forming at room temperature. Softening of the material by heat-assisted forming reduces the strain hardening and extended straining of the part which results in a reduction of the bulge height and of the under-forming of the cone base.

关键词： Single Point Incremental forming Global heating FE modeling

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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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Modeling of Transient Thermal Conditions in Cutting

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Journal of Mechanics Engineering and Automation 2017年第3期7卷 113-119页

作者： T. Augspurger F. Klocke B. Dobbeler M. Brockmann S. Gierlings A. Lima Laboratory for Machine Tools and Production Engineering R WTHAachen University Aachen 52056 Germany Fraunhofer Institute for Production Technology IPT R WTH Aachen University Aachen 52074 Germany

The thermal conditions like the temperature distribution and the heat fluxes during metal cutting have a major influence on the machinability, the tool lifetime, the metallurgical structure and thus the functionality of the work piece. This in particular applies for manufacturing processes like milling, drilling and turning for high-value turbomachinery components like impellers, combustion engines and compressors of the aerospace and automotive industry as well as energy generation, which play a major role in modern societies. However, numerous analytical and experimental efforts have been conducted in order to understand the thermal conditions in metal cutting, yet many questions still prevail. Most models are based on a stationary point of view and do not include time dependent effects like in intensity and distribution varying heat sources, varying engagement conditions and progressive tool wear. In order to cover such transient physics an analytical approach based on Green＇s functions for the solution of the partial differential equations of unsteady heat conduction in solids is used to model entire transient temperature fields. The validation of the model is carried out in orthogonal cutting experiments not only punctually but also for entire temperature fields. For these experiments an integrated measurement of prevailing cutting force and temperature fields in the tool and the chip by means of high-speed thermography were applied. The thermal images were analyzed with regard to thermodynamic energy balancing in order to derive the heat partition between tool, chips and workpiece. The thus calculated heat flow into the tool was subsequently used in order to analytically model the transient volumetric temperature fields in the tool. The described methodology enables the modeling of the transient thermal state in the cutting zone and particular in the tool, which is directly linked to phenomena like tool wear and workpiece surface modifications.

关键词： Metal cutting infrared thermography heat sources transient temperature fields model based on Green＇s functions.

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Assessing the Value of Data: An Approach to Evaluate the technology Driven Benefits of Smart Product Data

Assessing the Value of Data: An Approach to Evaluate the Tec...

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Portland International Conference on Management of Engineering and technology (PICMET)

作者： Guenther Schuh Ramon Kreutzer Marc Patzwald Laboratory for Machine Tools and Production Engineering (WZL) RWTH Aachen University Aachen Germany Fraunhofer-Institute for Production Technology IPT Aachen Germany

ISBN: (纸本)9781538629154;9781890843366

Data-centered and customer-oriented business models shape the digitalization to be the central social, economic and technological development of current knowledge societies. A great share of these new business models is enabled by smart product field data, which is generated during the product's phase of utilization. To capture the diluting value and commodification of mechanical products, companies within the manufacturing industry as the provider of smart products have to position themselves strategically against new competitors, e.g. from the IT sector, to avoid being victim to the "digital Darwinism". A growing number of manufacturing companies already starts to see the revenue and differentiation potential of smart product data as a competitive advantage. Similar to other intangible assets, a comprehensive understanding of the quality, scope and value of smart product field data is a basic prerequisite for its monetization. However, so far the majority of companies are lacking this basic understanding for the value of their smart product data, thus not being able to lever its potentials. Hence, this paper develops a model, which supports manufacturing companies in assessing, if a generic set of field data generated by a smart product is able to provide value added for the user. In the model itself, field data of smart products as well as "digitally enabled functionalities" will be examined extensively. Subsequently, generic sets of field data as carrier of information will be mapped regarding their suitability for enabling functionalities, which represent a demand of information.

关键词： Companies Economics Biological system modeling Manufacturing Data models Big Data

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Effect of the Welding Parameters on the Structural and Mechanical Properties of Aluminium and Copper Sheet Joints by Electromagnetic Pulse Welding

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World Journal of Engineering and technology 2016年第4期4卷 538-561页

作者： Irene Kwee Verena Psyk Koen Faes Belgian Welding Institute Zwijnaarde Belgium Fraunhofer Institute for Machine Tools and Forming Technology Fraunhofer Institute Chemnitz Germany

Aluminium-copper hybrid parts, as a substitution to copper parts, result in weight and cost reduction, and are relevant in applications related to the electronic, heating and cooling sector. However, aluminium to copper joined by thermal welding processes presents challenges in terms of achieving good joint quality. This is attributed to their dissimilar mechanical and thermal properties which result in large stress gradients during heating. This study investigated joining of aluminium to copper sheets by electromagnetic pulse welding, which is a solid-state process that uses electromagnetic forces for joining of dissimilar materials. Hybrid sheet welds were obtained for all parameters conditions, selected according to a Taguchi L18 design. The structural and mechanical characteristics were examined and related to the welding parameters by means of a Pareto analysis and response graphs. The welded zone started with a wavy interface with interfacial layers and defects and evolved to a flat interface without interfacial layers. The maximum transferable force depended on the minimum specimen thickness and the strength of the hybrid sheet weld. In case of aluminium sheet thickness reduction, the maximum transferable force was linearly correlated with the aluminium sheet thickness. High quality joints were obtained for no aluminium sheet thickness reduction and for a sheet weld strength which was at least as high as that of the base material. The most effective way to increase the transferable force was to lower the initial gap and to increase the free length, which resulted in no aluminium sheet thickness reduction. Alternatively, the use of a rounded spacer decreased the effect of the aluminium sheet thickness on the transferable force. An increase in weld width was achieved for an increase in capacitor charging energy and gap, whereas an increase in weld length was obtained for a decrease in gap. An increase in weld width did not necessarily result in an increase in t

关键词： Electromagnetic Pulse Sheet Welding Aluminum-to-Copper Welds Dissimilar Metal Welds Transferable Force Interfacial Morphology

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