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Modelling and simulation of fixtures during grinding

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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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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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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Applying modal analysis for comparing various FE models of human pelvic bone

Applying modal analysis for comparing various FE models of h...

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16th International Congress on Sound and Vibration 2009, ICSV 2009

作者： Werner, Michael Quickert, Martin Kunze, Holger Voigt, Christian Hoffmann, Falk Steinke, Hanno Fraunhofer Institute for Machine Tools and Forming Technology IWU Nöthnitzer Str. 44 01187 Dresden Germany University of Leipzig Department of Orthopaedic Surgery Laboratory for Biomechanics Liebigstr. 20 04103 Leipzig Germany University of Leipzig Institute of Anatomy Liebigstraße 13 04103 Leipzig Germany

ISBN: (纸本)9781615677368

Finite element analysis (FEA) is a wide-spread method for studying the mechanical properties of structures. Finite element models (FE models) are being increasingly used in medical technology and biomechanics for calculating dynamic problems with bones and artificial limbs. X-ray computer tomography data is used to create models that supply very precise information on morphology and tissue density. This article describes how experimental measurements of the dynamic behavior of the human hip bone can be obtained to verify different FE modeling approaches. Several mapping functions known from the literature will be used for material parameters in the FE models and the findings are compared. This paper specially focuses on the measuring method streamlined for fresh preparations using a 3-D laser vibrometer for the first time to capture oscillations threedimensionally.

关键词： Bone

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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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New approach for the characterisation of sheet materials - A precondition for the use of new sheet materials and forming processes

New approach for the characterisation of sheet materials - A...

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9th International Conference on technology of Plasticity, ICTP 2008

作者： Neugebauer, R. Sterzing, A. Müller, R. Silbermann, K. Fraunhofer Institute for Machine Tools and Forming Technology IWU Germany

ISBN: (纸本)9788957081525

The fraunhofer institute for machine tools and forming technology has set itself the challenge of characterising the material behaviour of very recently developed sheet metal materials. To this end, an integrated concept for the determination of material characteristics has been established. This consists in further developing well-known methods based on innovative characterisation concepts for describing phenomena such as springback, anistropy and the Bauschinger Effect. Using this approach, information relating to the interaction of sheet material, lubrication and forming tool can be derived.

关键词： Sheet metal

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Method for the compensation of process inherent form deviation in hot embossing of glass 10

Method for the compensation of process inherent form deviati...

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10th Anniversary International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2008

作者： Schubert, A. Edelmann, J. Fraunhofer Institute for Machine Tools and Forming Technology IWU Chemnitz Germany

ISBN: (纸本)9780955308253

During the hot pressing of glass (e.g. precision glass moulding, hot embossing) form deviations between the tool geometry and the manufactured glass formed part arise. Reasons for it are different thermal expansion behaviour of the materials and technological parameters. The form deviation resulting from these measured variables gains more and more significance with a rising scale of miniaturization. For the hot embossing of flat glass substrates with several cavities (e.g. micro lens arrays, microfluidic components) at the fraunhofer iwu a method was developed, in order to determine the total form deviation with the help of uncomplex shaped dies experimentally. The obtained accuracy is sufficient in order to correct ordinary optical geometries, like spherical cavities, or the pitch of V-grooves and channel structures respectively. For different tool materials and inorganic glasses according to this method correction factors were determined to compensate the process inherent form deviation. In this way complex iteration steps in the manufacturing of the tool moulds can be minimized.

关键词： Glass

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