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27th Danubia-Adria Symposium on Advances in Experimental Mechanics, DAS 2010

作者： Kretzschmar, Jens Stockmann, Martin Schiller, Sven Hellfritzsch, Udo Chemnitz University of Technology Faculty of Mechanical Engineering Department Mechanics of Solids Division Experimental Mechanics Chemnitz09107 Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Department Cold Massive and Precision Forming Reichenhainer Straße 88 Chemnitz09126 Germany

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Improvement of the power factor correction in machine tools

Improvement of the power factor correction in machine tools

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International (EPE-PEMC) Power Electronics and Motion Control Conference

作者： Reimund Neugebauer Artem Kolesnikov Markus Richter Joerg Paetzold Fraunhofer Institute of Machine Tools and Forming Technology Chemnitz Germany Institute of Machine Tools and Production Processes Chemnitz University of Technology Chemnitz Germany

An actual problem of the efficiency in machine tools is investigated by the improvement of the active power factor correction. An analysis of one method of the active power factor correction in machine tools is performed. A development of the active power factor correction is offered on the basis of the reduction of the power recovery in an infeed/regenerative module and the expansion of the dc link. The power factor correction in a machine tool is explored by means of experimental measurements and simulations of the electric system in a machine tool.

关键词： Reactive power Power factor correction machine tools Machining Converters Acceleration Cooling

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Improvement on straightness of metal bar based on straightening stroke-deflection model

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Science China(Technological Sciences) 2009年第7期52卷 1866-1873页

作者： LEOPOLD Juergen Fraunhofer Institute for Machine Tools and Forming Technology Chemnitz Germany

The straightening technics is one of important means to improve the straightness of metal bar. A novel way of predicting the straightening stroke is proposed based on mathematical methods and bending experimental and numerical simulation. The experimental and numerical simulation is conducted by following the mathematical load-stroke model of press straightening process under the elastic-plastic theory. For the linear guide rails, as an example, the stroke-deflection model focusing on the straightening stroke prediction can be achieved by contrasting and integrating the bending experimental results and finite element methods (FEM) simulation data. And then the formula for predicting the straightening stroke is presented based on the precise straightening stroke-deflection model. The stroke prediction formula with high precision can be applied to the straightening stroke prediction in the high straightness metal bar manufacturing process and automatic straightening machine conveniently.

关键词： straightness straightening stroke deflection stroke prediction metal bar

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Modelling and simulation of fixtures during grinding

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Science China(Technological Sciences) 2009年第7期52卷 1821-1829页

作者： Matthias KLAERNER Juergen LEOPOLD Lothar KROLL Institute of Mechanical and Polymer Engineering Chemnitz University of Technology09107 ChemnitzGermany Fraunhofer Institute for Machine Tools and Forming Technology 09126 ChemnitzGermany

The complex workpiece-fixture behaviour during machining is an essential component of the fixture development *** detail,the forces acting on fixture components have to be analysed.A method for the prediction of the reaction forces due to process and clamping loads is presented in this *** the beginning,detailed information about the workpiece-fixture behaviour during the process is determined by a complex finite element ***,the reduction of the number of elements leads to a smaller model with less computation time,validated and used for the variation of process ***,an analytical description is developed based on the combination of both *** the help of the empiric equation it is possible to predict the reaction forces and the dependency on several process *** method has been validated by modelling shape grinding of a nozzle guide vane.

关键词： clamping forces grinding finite element method fixture

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New coating strategy for hot embossing of glass 9

New coating strategy for hot embossing of glass

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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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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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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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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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