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9th International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2009

作者： Schubert, A. Edelmann, J. Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 Chemnitz09126 Germany

ISBN: (纸本)9780955308260

The hot embossing of glass received an enormous growth push through the mass production of aspheric lenses by precision glass moulding particularly in Asia in the last years. Deficits still exist regarding the accuracy and form filling, especially with double-sided embossed lenses or lens arrays, but also with non-optical applications as for instance micro fluidic systems. Particularly these structures with high aspect ratios, sharp edges and steep walls in structure design cause substantial problems during the demoulding after embossing. Here, conventional tool coating delivers only small improvements, probably also because the coating of moulds for fluid structures is very difficult and causes large problems. Against this background the research group at the fraunhofer IWU is breaking new ground with its coating strategy. Not the forming tool, but the glass is provided with a coating, which prevents a sticking of the tool material to the glass. © euspen Headquarters.

关键词： Coatings

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Milling strategies to improve accuracy and surface quality of microstructured parts 9

Milling strategies to improve accuracy and surface quality o...

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9th International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2009

作者： Neugebauer, R. Schubert, A. Schneider, J. Eckert, U. Chemnitz University of Technology Chemnitz09107 Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 Chemnitz09126 Germany

ISBN: (纸本)9780955308260

The ongoing miniaturization of milling tools leads to challenges particularly with regard to the selection of suitable machining strategies. Especially when machining high strength materials, significant problems in ensuring reliability and repeatability of the machining process are detected. Through the optimal selection of the machining strategy and the associated process parameters, improved accuracy and surface quality of moulds and prototypes can be achieved.

关键词： Surface properties

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Resource efficiency in bodywork parts production

Resource efficiency in bodywork parts production

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IEEE International Symposium on Assembly and Manufacturing (ISAM)

作者： Reimund Neugebauer Andreas Sterzing Fraunhofer Institute for Machine Tools and Forming Technology IWU Chemnitz Germany

The need for even greater efficiency in handling resources is coming to be seen as a public duty in politics, commerce and research. At the same time this raises the question of what options are open to companies in the manufacturing industries - and, in particular, the OEMs and suppliers to the automotive industry - for reducing costs as well as deployment of resources and emissions. In addition to illustrating and analysing the relevance of this topic as far as forming technology is concerned, the following article discusses a selection of approaches that are being adopted in the fraunhofer institute for machine tools and forming technology with a view to reducing the consumption of resources, particularly in the bodywork parts production sector.

关键词： Production machine tools Costs Raw materials Vehicles Energy efficiency Assembly Manufacturing industries Investments Chemical technology

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Investigations on process behavior in micro EDM using novel tool electrode materials

Investigations on process behavior in micro EDM using novel ...

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5th International Conference on Leading Edge Manufacturing in 21st Century, LEM 2009

作者： Uhlmann, Eckart Roehner, Markus Domingos, David Carlos Fraunhofer Institute for Production Systems and Design Technology Germany Institute for Machine Tools and Factory Management Technical University Berlin Germany

Experimental investigations in micro electrical discharge machining (EDM) aim to decrease the wear of tool electrodes using novel electrode materials such as boron doped CVD-diamond (B-CVD) and polycrystalline diamond (PCD). This paper presents the results of the latest investigations on process behaviour in micro electrical discharge machining. The characteristics of the plasma channel like ignition behaviour and channel expansion in the working gap are of great interest for reduction of tool electrode wear. Therefore single pulse discharges have been analysed and photographs have been taken of these discharges using a high speed framing camera. Moreover process behaviours of PCD and B-CVD were investigated and wear behavior, process time and working gap width analysed and compared to those of cemented carbide and tungsten copper.

关键词： Electric discharges

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Machining of nonconductive ZrO2 ceramics with micro-EDM 9

Machining of nonconductive ZrO2 ceramics with micro-EDM

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9th International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2009

作者： Schubert, A. Zeidler, H. Chemnitz University of Technology Micromanufacturing Technologies Chemnitz09107 Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Department Micro- and High-Precision Manufacturing Reichenhainer Str. 88 Chemnitz09126 Germany

ISBN: (纸本)9780955308260

Tests were undertaken using micro-EDM drilling with Tungsten Carbide Electrodes and ZrO2 ceramic. A starting layer, in literature often referred to as 'assisting electrode' was used to set up a closed electric circuit to start the EDM process. The usability of different electrically conductive layers, which were applied onto the substrate surface, as well as vibration superposition and different dielectric liquids such as deionised water and carbon hydride-based EDM-oil was examined. Using a specially designed low-frequency vibration setup to excite the workpiece (fig. 1), the process environment could be held within parameters to allow a constant EDM process even after the starting layer was machined. The machined structures and surface topologies were inspected using SEM and EDX technologies. The influences of the process parameters were analysed and an optimized strategy was set up. © euspen Headquarters.

关键词： Micromachining

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Internal cooling of cutting tools 9

Internal cooling of cutting tools

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9th International Conference and Exhibition on Laser Metrology, machine Tool, CMM and Robotic Performance, LAMDAMAP 2009

作者： Uhlmann, E. Roeder, M. Fries, E. Byrne, F. Institute for Machine Tools and Factory Management Technische Universität Berlin Germany Fraunhofer-Institute for Production Systems and Design Technology Berlin Germany

ISBN: (纸本)9780955308277

The development of cutting tools with closed internal cooling systems has been the subject of recent research. The implementation of such a technology would bring many advantages in the cutting process. The generated heat can be removed from the process through the use of cooling structures inside the cutting tool without contamination of the cooling fluid. The challenge in the design of an internally cooled tool is to find the optimal balance between the tool's thermal and mechanical properties. Due to the low thermal conductivity of cemented carbides the cooling structures must be as close as possible to the tool tip, without weakening the mechanical stability. Cutting experiments have shown that internal cooling can be effective as an alternative to or in addition to conventional cooling. Experiments were carried out with different cooling structure designs and workpiece materials. Tool wear was evaluated, the machined surfaces analysed, and the results compared with those using conventional cooling processes. Furthermore, the thermal performance and the mechanical stability of the tool were examined in a series of FEM-simulations. With a continuous temperature gradient between the tool tip and the cooling structure thermal shock can be minimised and the tool life increased. Finally, the internal cooling system offers the potential to measure and influence the tool temperature.

关键词： Cutting tools

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Numerical analysis of crack propagation during the burr formation process of metals

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International Journal of Machining and Machinability of Materials 2009年第1-2期6卷 54-68页

作者： Regel, J. Stoll, Anke Leopold, Juergen Institute of Machine Tools and Production Processes Chemnitz University of Technology Chemnitz Germany Department of Materials University of Oxford Oxford United Kingdom Fraunhofer Institute for Machine Tools and Forming Technology Chemnitz Germany

Because of increased productivity demands in manufacturing the attention in burr problems is steadily turned to the avoidance of burr. With this initial point this paper contributes to the analysis and simulation of burr separation at workpiece material AISI 1045 steel (C45E). At first 12 known crack initiation criteria are investigated whether they are suitable to simulate crack initiation during burr formation. It is shown that eight criteria are suitable for the prediction of the crack, whereas the criterion from Cockcroft and Latham has to be pointed out. The implementation of the failure conception of ductile damage from Lemaitre and Sievert indicates the applicability for burr formation simulation with simultaneous simulation of segmented chips. In first calculation, a sliding of the chip could be simulated. At the end the hypothesis of the 'hydrostatic bowl', an area of highly negative pressure in the stage of burr formation, is used to predict the location of crack initiation. The established values correlate better to the experimental tests than these, which are determined by means of fracture criteria. Copyright © 2009, Inderscience Publishers.

关键词： Finite element method

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Manufacturing of lightweight frame structures by joining of (none-) reinforced profiles

Manufacturing of lightweight frame structures by joining of ...

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Materials Science and technology Conference and Exhibition 2009, MS and T'09

作者： Marré, M. Ruhstorfer, M. Tekkaya, A.E. Zaeh, M.F. Institute of Forming Technology and Lightweight Construction IUL Technische Universitaet Dortmund Dortmund Germany Institute for Machine Tools and Industrial Management Technische Universitaet Muenchen Munich Germany

ISBN: (纸本)9781615676361

Within the German Collaborative Research Center SFB/TR10 new composite materials are produced by composite extrusion and shall be joined to a lightweight frame structure. Lightweight profiles and sheet metals manufactured by composite extrusion are made of an aluminum matrix and embedded steel wires. The joining of reinforced and conventional profiles has been investigated taking joining by hydroforming, joining by electromagnetic compression and Friction Stir Welding into account. The paper presents how to assemble such composite profiles as well as the joining processes and strategies which were developed for machining the composite material. Experimental and analytical investigations are presented for joining by forming and welding techniques. Furthermore, guidelines are given which describe the execution of the joining process as well as the joint design. This paper gives a general review of the scientific work in joining of the Collaborative Research Center during the years 2006 to 2009. Therefore, the presented results were partly published at ICNFT07 (Bremen, Germany) [1], Esaform 09 (Twente, The Netherlands) [2] and IS on FSW09 (Awaji Island, Japan) [3].

关键词： Friction stir welding

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The possibilities of and limits to detecting incomplete fusion via in-process monitoring in the case of laser welding

The possibilities of and limits to detecting incomplete fusi...

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International Conference on Emerging Technologies and Factory Automation (ETFA)

作者： Michael Kuhl Paul-Michael Mickel Fraunhofer Institute of Machine Tools and Forming Technology Chemnitz Germany Volkswagen Sachsen GmbH Zwickau Germany

ISBN: (纸本)9781424427277

Laser welding has a whole series of benefits such as high welding velocity or minor heat yield which is why it is becoming increasingly important. Meeting strength and quality requirements for welding seams is of eminent significance in automobile design. Unfortunately, there might be problems due to the degassing gaps needed between the joining parts when using the galvanized sheet metal that is customary in car body design. This causes incomplete fusion to form with excessively large gap dimensions that cannot be identified from outside. Nor do process monitoring systems available on the market detect these faults with sufficient reliability. VW Sachsen GmbH and the fraunhofer institute for machine tools and forming technology studied the reasons for the inadequacies of conventional systems in the MAINE X joint research project. This article presents the findings and makes recommendations for sufficient methods of detection.

关键词： Laser fusion Welding Signal processing Fault detection Chemical lasers machine tools Gas lasers Coaxial components Condition monitoring Chemical technology

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Improving the precision by thermal simulation

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ATZproduktion worldwide 2009年第3期2卷 4-9页

作者： Neugebauer, Reimund Zwingenberger, Carsten Kehl, Gerhard Fraunhofer Institute for Machine tools and Forming technology IWU Chemnitz Germany Gebr. Heller Maschinen-fabrik GmbH in Nürtingen Germany

In the development of modern machine tools for the automotive industry, higher productivity, higher metal removal rates and lower machining tolerances are increasingly calling for allowance to be made for misalignments due to thermal factors. Improving the accuracy of thermal simulation was the subject of a project conducted at the fraunhofer institute for machine tools and forming technology (IWU).

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