Aluminum foam sandwiches are laminates with an aluminum foam core and compact cover sheets. The foam cores possess a high energy absorption capacity. machine tool assemblies made of aluminum foam sandwiches offer very...
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ISBN:
(纸本)9781932078282
Aluminum foam sandwiches are laminates with an aluminum foam core and compact cover sheets. The foam cores possess a high energy absorption capacity. machine tool assemblies made of aluminum foam sandwiches offer very high flexural stiffness, together with comparatively light weight. Vibrations generated by machining are damped very well due to the cellular structure of foam. The manufacturing process of foam sandwiches is in general well understood, but there are still some open questions concerning the mechanisms of bonding and adhesion between cover sheets and foam core. This paper tries to give answers to these questions.
The need for high-aspect ratio micro structures in hard to machine materials is constantly growing. Electro-Physical machining processes such as EDM offer distinct advantages to conventional machining technologies suc...
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ISBN:
(纸本)9780955308253
The need for high-aspect ratio micro structures in hard to machine materials is constantly growing. Electro-Physical machining processes such as EDM offer distinct advantages to conventional machining technologies such as independence of material hardness, but are difficult to control for high-precision and micro applications [1]. It is therefore of great importance to provide means of fast and stable machining in Micro-EDM, e.g. optimize process and discharge efficiency. In this study, a novel approach to characterize erosion efficiency in Micro-EDM is made by recording erosion current and voltage with high resolution and long recording time. The paper presents the objectives of pulse shape classification for micro-EDM and lines out how a rating of erosion efficiency can be realized by studying the number and sequence of current and voltage of the erosion pulses. Thus, process analysis can be improved and optimized parameters can be adopted to the process state, eventually leading to an on-line process control.
In Jet Electrochemical Machining (Jet-ECM), the electrolytic current between the anodic work piece and the cathodic nozzle is supplied via an electrolyte jet which is ejected from a nozzle. The main advantage compared...
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ISBN:
(纸本)9780955308253
In Jet Electrochemical Machining (Jet-ECM), the electrolytic current between the anodic work piece and the cathodic nozzle is supplied via an electrolyte jet which is ejected from a nozzle. The main advantage compared to other EC processes is the restriction of the electrolytic current to a limited area by the jet. The dissolution rate and the machining position can easily be controlled by setting the electric current and the nozzle position. Higher dissolution rates compared to pulsed ECM are possible, because continuous direct current is applied. In this study the property of using an additional jet of compressed air to assist the procedure is presented. The additional jet of compressed air removes the electrolyte film enclosing the metallic nozzle, which is caused by surface tension. Thereby localisation is enhanced and working gaps of about 100 um (distance between work piece and nozzle) can be used. Furthermore a FEM model was developed to simulate selected processing results.
In today's mechanical engineering aluminum foam is no longer an unknown material. It is already used where lightweight construction and structural damping are required. Especially in sandwich composites with steel...
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ISBN:
(纸本)9781932078282
In today's mechanical engineering aluminum foam is no longer an unknown material. It is already used where lightweight construction and structural damping are required. Especially in sandwich composites with steel, the advantages of foam as rigid core become evident. For the production of aluminum foam often foamable semi-finished products are used that are fabricated by the molten powder metallurgical procedure. These semifinished products can be made with almost any cross section. During the foaming process the volume increases enormously so that it is possible to fill large volumes and gaps with the generated foam. Besides, aluminum foam is thermally resistant up to about 500C, it can be joined with metals during the foaming process, and it shrinks significantly during cooling. If one compares these facts with known applications of other materials the idea of "aluminum foam - a composite material" immediately comes to mind.
As the compression behaviour has been identified as one of the key properties of cellular materials, a draft for a standard for the compression test for cellular metals was developed and discussed within the German/Au...
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ISBN:
(纸本)9781932078282
As the compression behaviour has been identified as one of the key properties of cellular materials, a draft for a standard for the compression test for cellular metals was developed and discussed within the German/Austrian working group on cellular materials. The test and evaluation procedure outlined in the present paper pays special attention to problems linked with the inhomogeneity of most cellular materials, the structure-dependent stiffness and variations in the shape and length of the plateau regime in the stress-strain curve. The paper provides experimental support for the decision on the test and evaluation procedure and examples for the application of the draft on several kinds of cellular metals.
One of the preconditions for achieving process reliability in the increasingly automated manufacturing processes in the automotive industry is controlled chip breakage. The joint research project “Strategies for the ...
One of the preconditions for achieving process reliability in the increasingly automated manufacturing processes in the automotive industry is controlled chip breakage. The joint research project “Strategies for the Guarantee of Controlled Chip Breakage”, which was carried out at RWTH Aachen and was funded by the Research Association for machinetools and Manufacturing technology, was aimed at developing an expert system that can predict controlled chip breakage during machining processes without time-consuming preliminary testing. The key component of this newly developed software is a database that is based on known machining cases.
For various applications, such as object recognition or tracking and especially when the object is partly occluded or articulated, 3D information is crucial for the robustness of the application. A recently developed ...
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For various applications, such as object recognition or tracking and especially when the object is partly occluded or articulated, 3D information is crucial for the robustness of the application. A recently developed sensor to acquire distance information is based on the Photo Mixer Device (PMD)for which a distance error based on different causes can be observed. This article presents an improved distance calibration approach for PMD-based distance sensoring which handles objects with different Lambertian reflectance properties. Within this scope the relation of the sources of distance errors were investigated. Where applicable they were isolated for relational studies with the actuating variables, i.e. integration time, amplitude and measured distance, as these are the only parameters available for the calibration. The calibration results of the proposed method excel the results of all other known methods. In particular with objects with unknown reflectance properties a significant reduction of the error is achieved.
This paper reviews current developments in mechatronic systems for metal cutting and formingmachinetools. The integration of mechatronic modules to the machine tool and their interaction with manufacturing processes...
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This paper reviews current developments in mechatronic systems for metal cutting and formingmachinetools. The integration of mechatronic modules to the machine tool and their interaction with manufacturing processes are presented. Sample mechatronic components for precision positioning and compensation of static, dynamic and thermal errors are presented as examples. The effect of modular integration of mechatronic system on the reconfigurability and reliability of the machinetools is discussed along with intervention strategies during machine tool operation. The performance and functionality aspects are discussed through active and passive intervention methods. A special emphasis was placed on active and passive damping of vibrations through piezo, magnetic and electro-hydraulic actuators. The modular integration of mechatronic components to the machine tool structure, electronic unit and CNC software system is presented. The paper concludes with the current research challenges required to expand the application of mechatronics in machinetools and manufacturing systems.
The German BMBF-supported joint project "3D-Mikro" [1] aims to the integration of 3D-coordinate measurement equipment into highest precision machinetools. By inprocess measuring of tool geometries and workp...
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ISBN:
(纸本)0955308224
The German BMBF-supported joint project "3D-Mikro" [1] aims to the integration of 3D-coordinate measurement equipment into highest precision machinetools. By inprocess measuring of tool geometries and workpiece structures the uncertainties resulting from multiple clamping should be eliminated or at least diminished. The main focus of the research activities at fraunhofer IWU is the investigation and adaptation of suitable non-contact working sensors for pre-measuring of the microcutting tool and the micro-workpiece. In this article some selected results of the running test program are shown.
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