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Process Analysis of Water Abrasive Fine Jet Structuring of Ceramic Surfaces via Design of Experiment

Procedia CIRP 2014年 14卷 442-447页

作者： M. Dittrich M. Dix M. Kuhl B. Palumbo F. Tagliaferri Technische Universität Chemnitz Institute for Machine Tools and Production Processes (IWP) Reichenhainer Str. 70 09126 Chemnitz Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 09126 Chemnitz Germany University of Naples Federico II Department of Industrial Engineering (DII) Piazzale V. Tecchio 80 80125 Naples Italy

Machining of aluminum oxide Al2O3 can be classified as challenging by reason of its brittle and high tensile material behavior. Moreover, conventional processes for machining ceramics, e.g. using laser beam or lapping, are typically associated with lower material removal rates and high manufacturing costs. Cutting using water abrasive jet enables cutting of ceramics due to exceedingly low process forces and machining temperatures. In addition to the actual cutting process, surface structuring can be carried out using a reflecting jet by a specific adjustment of process parameters. In this context, water abrasive fine jet machining is up-and-coming due to better charge and higher precision. These factors allow the insert of the smallest geometries which either cannot be manufactured by primary shaping or are suitable for manufacturing only to a limited extent. This article describes how a process design is being executed concerning productivity and machining precision by using an analysis based on the method of the Design of Experiments (DoE). The most influencing parameters become apparent, such as water pressure, abrasive flow rate or path offset. The parameters allow a specific process dimensioning in terms of material removal rate, surface roughness and depth of penetration. Furthermore the investigations show a high reproducibility of the results using appropriate process parameters. The study illustrates that the use of the water abrasive injector fine jet permits a precise and highly efficient insertion of surface structures into ceramic materials.

关键词： water abrasive jet structuring ceramic machining design of experiments (DoE) ANOVA.

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Shape memory polymer based contact faces for flexible car body fixtures 22

Shape memory polymer based contact faces for flexible car bo...

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22nd International Conference on Production Research, ICPR 2013

作者： Keller, C. Drossel, W.-G. Pfeifer, M. Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 Chemnitz09126 Germany

The paper describes the status of research concerning the flexibilization of contact faces. For an extensive use of systems for flexible car body fixtures it is necessary to develop flexible contact elements to adapt the clamp to diverse part faces. For this different approaches are shown. Especially the approach of using shape-memory material to make contact faces flexible is discussed. Selected experiments were done. This was the first time the shape-memory effect has been shown on voluminous bodies. The material was activated using an induction field via filler. This way of activating voluminous bodies also has been shown for the first time. The usability of shape-memory polymers was demonstrated and the next steps were shown.

关键词： Railroad cars

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Structure-borne sound source and transfer path analysis of coupled structures using the example of a railway air conditioning unit

Structure-borne sound source and transfer path analysis of c...

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42nd International Congress and Exposition on Noise Control Engineering 2013: Noise Control for Quality of Life, INTER-NOISE 2013

作者： Knöfel, Björn Troge, Jan Drossel, Welf-Guntram Kunze, Holger Linke, Moritz Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Straße 88 09126 Chemnitz Germany

ISBN: (纸本)9781632662675

Within a research project at the fraunhofer institute for machine tools and forming technology IWU, vibration description methods are applied using the example of an air conditioning unit (AC unit) from a railway vehicle. The AC unit consists of several components, where usually the compressors and fans contribute most to the radiated sound power resp. to the transmitted structure-borne sound into the vehicle. In a first step, forces F and accelerations a under steady-state conditions were measured on each of the six mounting brackets of the air conditioning unit. Afterwards, all of the dominant vibration sources of the unit were investigated individually concerning their contribution at each of their contact points. Finally, knowing the mobilities Y of the contact points between sources and unit enables detailed analysis of the system itself. Moreover, it also indicates "weak points" which have to be avoided according to an improved vibrational behavior of the complete air conditioning unit.

关键词： machine tools

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Industrial Applications of Shape Memory Alloys - Potentials and Limitations

Industrial Applications of Shape Memory Alloys - Potentials ...

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GMM/ETG-Fachtagung Innovative Klein- und Mikroantriebstechnik

作者： Andre Bucht Kenny Pagel Christoph Eppler Holger Kunze Fraunhofer Institute of Machine Tools and Forming Technology

ISBN: (纸本)9783800735372

Shape Memory Alloys are well known and established in medical engineering. In recent years their importance considering industrial applications also increased. Especially the high specific work load of the material and the simple working principle of SMA actuator systems possess them to be a suitable alternative to conventional drives. The benefits of the technology directly address the main demands on actuator technologies like miniaturisation, lightweight design and costs. Further SMAs can be an alternative to substitute rare earth metals. In the paper we present the status quo of SMA technology. The shape memory effect as a basis for understanding the working principles of such actuators is described. Beyond that mechanical design rules are explained. That covers the three possible actuating principles constant- and spring loaded and antagonistically arranged SMA actuators. Besides simple switching applications, there are rather complex controlled SMA actuators using external sensors or inherent resistance feedback. Control principles for both approaches are presented. To show potentials but also the limitations of SMA actuators, applications from different markets with different demands are described. They specify the certain challenges which have to be overcome before a comprehensive market acceptance of SMAs in industrial applications can be expected. The estimated developments in the future will be discussed further.

关键词： Shape memory alloys Industrial applications actuators Stone matrix asphalt operating principles medical engineering Rare Earth Metals shape memory effects

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Simulation of the 3D sound propagation and radiation of a railway air conditioning unit based on transfer matrix techniques

Simulation of the 3D sound propagation and radiation of a ra...

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42nd International Congress and Exposition on Noise Control Engineering 2013: Noise Control for Quality of Life, INTER-NOISE 2013

作者： Troge, Jan Starobinski, Rudolf Drossel, Welf-Guntram Kunze, Holger Knöfel, Björn Linke, Moritz Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Straße 88 09126 Chemnitz Germany Silencers. Consulting and engineering Dorotheenstraße 76 22301 Hamburg Germany

ISBN: (纸本)9781632662675

The air conditioning unit (AC unit) is one of the major sound sources for exterior and interior noise of a railway vehicle. The design of such devices is a compromise between main functions like efficiency, fluid mechanics, thermodynamics and acoustics. Especially the acoustical behavior of an air conditioning unit needs to be quantified in every state of the development process, starting in an early design phase. For this purpose preferably simple and fast calculation tools are needed, which can be easily built up and adapted in a short time. Within a research project at the fraunhofer institute for machine tools and forming technology IWU an acoustical calculation model, based on transfer matrices of the different components, has been created to give a sufficiently accurate description of the sound power radiated by an AC unit. In a first step, the sound power of important sources has been characterized by measurement data. Furthermore, the acoustical transfer behavior of ducts and additional components like condensers or evaporators has been individually investigated and implemented in the model using transfer elements. Finally, the sources and transfer components were combined to give a complete representation of the acoustical properties of the air conditioning unit, which can be used for parameter variation studies and noise reduction. Copyright© (2013) by Austrian Noise Abatement Association (OAL).

关键词： Noise abatement

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Reduction of surface imperfections in turning of aluminium matrix composites by an appropriate cutting edge design 13

Reduction of surface imperfections in turning of aluminium m...

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13th International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2013

作者： Nestler, A. Schubert, A. Chemnitz University of Technology Department of Micromanufacturing Technology 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)9780956679024

In the majority of cases, aluminium matrix composites (AMCs) consist of a relatively ductile matrix and hard ceramic particles embedded therein. In addition to an increased tool wear, machining of these materials involves surface imperfections like voids and scaling. An approach to reduce the generation of suchlike imperfections is a modification of the cutting edge geometry. Turning tests have shown that smooth surfaces can be generated by using natural diamond tipped tools with a very small clearance angle of approximately 0.5 and a minor feed of 0.05 mm.

关键词： Turning

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Process optimisation in the manufacturing of the bedplate

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MTZ worldwide 2013年第6期74卷 42-46页

作者： Gerth, Nancy Sauer, Helfried Gebauer, Mathias Rädel, Thomas DGH-Group Druckguss Heidenau GmbH Dohna Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Dresden Germany

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Mechatronic sketching of manufacturing systems using Physically Based Models A novel approach for simulation-based systems engineering

Mechatronic sketching of manufacturing systems using Physica...

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IEEE Symposium on Industrial Electronics & Applications (ISIEA)

作者： Peter Stich Gunther Reinhart Research-Department for Resource-Efficient Processing Machines (RMV) Fraunhofer Institute for Machine Tools and Forming Technology (IWU) Augsburg Germany

Simulation is established within the development process in order to validate technical systems at an early stage. Nonetheless, the required level of detail and the late availability of simulation models limit an economic application. This paper describes a novel approach for an interactive and mechatronic design of technical alternatives at early stages of development and in this regard the evaluation with physically based simulation models.

关键词： Mechatronics Computational modeling Manufacturing systems Data models Biological system modeling

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Manufacturing of Twist-free Surfaces by Hard Turning

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Procedia CIRP 2013年 7卷 294-298页

作者： Andreas Schubert Ran Zhang Philipp Steinert Technische Universität Chemnitz Faculty of Mechanical Engineering Professorship Micromanufacturing Technology 09126 Chemnitz Germany Fraunhofer Institute for Machine Tools and Forming Technology 09126 Chemnitz Germany

Currently grinding is commonly used as the finishing operation to manufacture seal mating surfaces and bearing surfaces, especially in the automotive industry. It would lead to more resource-efficient production if the cost- and energy-intensive grinding process could be replaced by machining with geometrically defined cutting edges, such as hard turning [1] , [2] . However, turning operations usually cause a twist structure on the surface, which can convey lubricants like a pump. Several methods exist to overcome this problem, for example, tangential turning, rotation turning and turn broaching, etc. Due to the high costs of tools and special machines required by these methods, the industrial application is still limited. This paper describes a more efficient approach by applying a modified feed kinematic. When using this approach, hard turning produces twist-free surfaces. The results of the latest twist test methods have confirmed that the surfaces are free of twist, hence free of conveying effect of lubricant and that they are suitable for application in manufacturing of seal mating surfaces and bearing surfaces. Furthermore, this method requires only minimal investment in any turning machine.

关键词： Cutting Surface Tribology Turning Wear

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Micro-EDM Milling of Electrically Nonconducting Zirconia Ceramics

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Procedia CIRP 2013年 6卷 297-302页

作者： A. Schubert H. Zeidler M. Hahn M. Hackert-Oschätzchen J. Schneider Chair Micromanufacturing Technology Faculty of Mechanical Engineering Chemnitz University of Technology D-09107 Chemnitz Germany Fraunhofer-Institute for Machine Tools and Forming Technology IWU Reichenhainer Strasse 88 D-09126 Germany

Micro-EDM is a well-known process for precision micro machining of difficult to cut materials. It is especially beneficial when machining complex micro structures such as deep bores, grooves or undercuts in highly wear resistant materials. One constraint is its limitation to electrically conductive materials. Advanced materials such as high-temperature resistant engineered ceramics are gaining more and more importance, nonetheless due to their manifold applications in transport, energy and also biomedical areas. An adaption of micro-EDM to nonconducting ceramics could bring together the design freedom implemented in the EDM process and the beneficial material properties of engineered ceramics. In the last years, research has successfully applied the assisting electrode method to zirconia material, allowing for the micro-EDM to proceed notwithstanding the electrically nonconducting properties. Using suitable dielectric and process parameters, the machining continues even after the electrically conducting starting layer has been removed. Within this study the micro-EDM milling of zirconia is investigated in order to further understand the mechanisms of ceramics machining. Roughness and surface characteristics are analyzed and compared to the equivalent metal parts. The voltage and current signals are recorded using high speed deep memory A/D converters to allow for an insight into the process. With the findings the process can be improved in terms of speed, accuracy and achievable structures.

关键词： Micro-EDM Ceramics Zirconia EDM milling

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