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Technologies for the mechanical joining of aluminum die castings

AIP Conference Proceedings 2019年第1期2113卷

作者： Thomas Grimm Mathias Jäckel Tobias Falk Welf-Guntram Drossel 1Fraunhofer Institute for Machine Tools and Forming Technology IWU Nöthnitzer Straße 44 01187 Dresden Germany

This paper shows a comparison of existing self-pierce riveting technologies with the newly developed self-pierce riveting with solid formable rivet (SPR-SF) for the joining of Aluminum die casts. The challenges during the mechanical joining of the Aluminum die cast AlSi9Mn by different joining technologies like self-pierce riveting with semi-tubular rivet (SPR-ST), self-pierce riveting with moveable die element and semi-tubular rivet (S-SPR-ST), self-pierce riveting with solid rivet (SPR-S) and self-pierce riveting with solid formable rivet (SPR-SF) will be discussed and the joining technologies in regard to process force, interlock, shear tensile strength and top tensile strength will be analyzed.

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Testing of magnetic pulse welded joints – Destructive and non-destructive methods

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AIP Conference Proceedings 2019年第1期2113卷

作者： Verena Psyk Christian Hofer Koen Faes Christian Scheffler Edgar Scherleitner 1Fraunhofer Institute for Machine Tools and Forming Technology Reichenhainer Strasse 88 09126 Chemnitz Germany 2Research Center for Non Destructive Testing GmbH (RECENDT) Altenberger Straße 69 4040 Linz Austria 3Belgian Welding Institute BWI Technologiepark 935 9052 Zwijnaarde Belgium

Electromagnetic pulse welding is an innovative technology suitable for joining various similar and dissimilar tube and sheet metal parts including dissimilar material combinations, which are difficult to join by conventional, i.e. thermal welding methods. In case of proper choice of process parameters, a high joint quality can be achieved. In literature this is often demonstrated by failure in the base material during destructive testing. However, no standard testing procedures for magnetic pulse welded joints have been agreed on and thus industrial implementation is severely complicated. Specifically, investigations regarding non-destructive testing are rarely available. The paper evaluates different testing and characterization methods. Specifically, metallographic analysis and lap shear tests are taken into consideration. Finally, Laser UltraSound (LUS) is presented as a new alternative for characterizing magnetic pulse welded joints. The technique is based on measuring laser ultrasound waves which are either transmitted through or reflected by the weld seam. A comparison of the results to those of the more established destructive testing methods shows, that LUS measurements absolutely allow qualitative and quantitative conclusions regarding weld quality. Due to high automation potential, the method is a promising alternative for quality control in industrial manufacturing.

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Highly elastic strain gauges based on shape memory alloys for monitoring of fibre reinforced plastics 21st

Highly elastic strain gauges based on shape memory alloys fo...

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21st Symposium on Composites, 2017

作者： Mäder, Thomas De Sosa, Iñaki Navarro Y. Senf, Björn Wolf, Peter Hamm, Martin Zoch, Martin Drossel, Welf-Guntram Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Straße 88 Chemnitz09126 Germany Prof. for Adaptronics and Lightweight Design Technische Universität Chemnitz Chemnitz09107 Germany FiberCheck GmbH Technologie-Campus 1 Chemnitz09126 Germany

ISBN: (纸本)9783035711981

Conventional strain gauges made of constantan or CuCr for instance have a low value for structural health monitoring issues in plastic composites. These strain sensor materials exhibit small elastic regions and show fatigue when dynamically loaded with strain levels over 0.3 percent. For this reason, these sensors would break or fail before the composite life-time and thus cannot be integrated into this kind of composite materials. Pseudoelastic thermal shape memory alloys are therefore used as strain sensors and integrated into composites in order to allow piezoresistive strain measurement and structural health monitoring in such materials. Thermal treatments are used to create sensor structures out of shape memory alloy wires. Pseudoelastic shape memory wires can be strained up to 8 percent repeatedly. Their gauge factor is higher than 5. Shape memory strain sensors are successfully embedded into glass fibre reinforced plastics and show a significant and reproducible resistance change when the composite is strained. The dynamic strength is magnificently higher compared to conventional strain gauges. Shape memory strain sensors are an efficient alternative to fiber-bragg-grating sensors and can potentially be used for strain measurements in different plastics and textile materials. Shape memory sensor structures can be embedded or applied and are good candidates for structural characterisation and monitoring applications. © 2017 Trans Tech Publications, Switzerland.

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Surface structuring of boron doped CVD diamond by micro electrical discharge machining

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AIP Conference Proceedings 2018年第1期1960卷

作者： A. Schubert T. Berger A. Martin M. Hackert-Oschätzchen N. Treffkorn R. Kühn 1Professorship Micromanufacturing Technology Faculty of Mechanical Engineering Chemnitz University of Technology 09107 Chemnitz Germany 2Fraunhofer Institute for Machine Tools and Forming Technology 09126 Chemnitz Germany

Boron doped diamond materials, which are generated by Chemical Vapor Deposition (CVD), offer a great potential for the application on highly stressed tools, e. g. in cutting or forming processes. As a result of the CVD process rough surfaces arise, which require a finishing treatment in particular for the application in forming tools. Cutting techniques such as milling and grinding are hardly applicable for the finish machining because of the high strength of diamond. Due to its process principle of ablating material by melting and evaporating, Electrical Discharge Machining (EDM) is independent of hardness, brittleness or toughness of the workpiece material. EDM is a suitable technology for machining and structuring CVD diamond, since boron doped CVD diamond is electrically *** this study the ablation characteristics of boron doped CVD diamond by micro electrical discharge machining are investigated. Experiments were carried out to investigate the influence of different process parameters on the machining result. The impact of tool-polarity, voltage and discharge energy on the resulting erosion geometry and the tool wear was analyzed. A variation in path overlapping during the erosion of planar areas leads to different microstructures. The results show that micro EDM is a suitable technology for finishing of boron doped CVD diamond.

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Characterization of material parameters for high speed forming and cutting via experiment and inverse simulation

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AIP Conference Proceedings 2018年第1期1960卷

作者： Christian Scheffler Verena Psyk Maik Linnemann Marc Tulke Alexander Brosius Dirk Landgrebe 1)Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 D-09112 Chemnitz 2)Technische Universität Dresden Chair of Forming Processes FF D-01062 Dresden

High speed velocity effects in production technology provide a broad range of technological and economic advantages [1, 2]. However, exploiting them necessitates the knowledge of strain rate dependent material behavior in process modelling. In general, high speed material data characterization features several difficulties and requires sophisticated approaches in order to provide reliable material data. This paper proposes two innovative concepts with electromagnetic and pneumatic drive and an approach for material characterization in terms of strain rate dependent flow curves and parameters of failure or damage models. The test setups have been designed for investigations of strain rates up to 105 s-1. In principle, knowledge about the temporary courses and local distributions of stress and strain in the specimen is essential for identifying material characteristics, but short process times, fast changes of the measurement values, small specimen size and frequently limited accessibility of the specimen during the test hinder directly measuring these parameters at high-velocity testing. Therefore, auxiliary test parameters, which are easier to measure, are recorded and used as input data for an inverse numerical simulation that provides the desired material characteristics, e.g. the Johnson-Cook parameters, as a result. These parameters are a force equivalent strain signal on a measurement body and the displacement of the upper specimen edge.

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A Production Planning Method to Optimally Exploit the Potential of Reconfigurable Manufacturing Systems

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Procedia CIRP 2017年 62卷 181-186页

作者： Andreas Hees Christina Bayerl Brian Van Vuuren Corné S.L. Schutte Stefan Braunreuther Gunther Reinhart Fraunhofer Institute for Machine Tools and Forming Technology (IWU) Project Group Resource-efficient Mechatronic Processing Machines Beim Glaspalast 5 86153 Augsburg Germany Stellenbosch University Department of Industrial Engineering Private Bag X1 Stellenbosch 7602 South Africa

Manufacturing companies must operate in a dynamic environment. Consequently, companies constantly have to adapt their manufacturing systems to stay competitive. One approach to ensure the success of manufacturing companies is to use reconfigurable manufacturing systems (RMS). Current production planning methods cannot quickly realize the production-side adaptions available in RMS and are limited in flexibility. A novel production planning method to optimize the potential of RMS is presented in this paper. First, the key characteristics and planning requirements for an RMS are defined. A feasible configuration is then determined, using a planning method based on mixed integer linear programming (MILP) to realize capacity scalability and functionality changes within planning processes. Finally, an application scenario to validate the method is outlined.

关键词： Production planning Reconfiguration Scheduling

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Numerical-experimental investigation of load paths in DP800 dual phase steel during Nakajima test

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AIP Conference Proceedings 2018年第1期1960卷

作者： Thomas Bergs Matthias Nick Andreas Feuerhack Daniel Trauth Fritz Klocke 1Fraunhofer Institute for Production Technology IPT Steinbachstraße 17 52074 Aachen Germany 2Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University Chair for Manufacturing Technology Campus-Boulevard 30 52074 Aachen Germany

Fuel efficiency requirements demand lightweight construction of vehicle body parts. The usage of advanced high strength steels permits a reduction of sheet thickness while still maintaining the overall strength required for crash safety. However, damage, internal defects (voids, inclusions, micro fractures), microstructural defects (varying grain size distribution, precipitates on grain boundaries, anisotropy) and surface defects (micro fractures, grooves) act as a concentration point for stress and consequently as an initiation point for failure both during deep drawing and in service. Considering damage evolution in the design of car body deep drawing processes allows for a further reduction in material usage and therefore body weight. Preliminary research has shown that a modification of load paths in forming processes can help mitigate the effects of damage on the *** paper investigates the load paths in Nakajima tests of a DP800 dual phase steel to research damage in deep drawing processes. Investigation is done via a finite element model using experimentally validated material data for a DP800 dual phase steel. Numerical simulation allows for the investigation of load paths with respect to stress states, strain rates and temperature evolution, which cannot be easily observed in physical experiments. Stress triaxiality and the Lode parameter are used to describe the stress states. Their evolution during the Nakajima tests serves as an indicator for damage evolution. The large variety of sheet metal forming specific load paths in Nakajima tests allows a comprehensive evaluation of damage for deep drawing. The results of the numerical simulation conducted in this project and further physical experiments will later be used to calibrate a damage model for simulation of deep drawing processes.

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Hot metal gas forming of titanium grade 2 bent tubes

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AIP Conference Proceedings 2017年第1期1896卷

作者： Alexander Paul Markus Werner Ricardo Trân Dirk Landgrebe 1Fraunhofer Institute for Machine Tools and Forming Technology Reichenhainer Straße 88 D-09126 Chemnitz Germany 2TU Bergakademie Freiberg Institute of Metal Forming Bernhard-von-Cotta-Straße 4 D-09599 Freiberg Germany

Within the framework of investigations, an exhaust gas component made of Titanium Grade 2 was produced by means of Hot Metal Gas forming (HMGF) at the fraunhofer IWU in Chemnitz, *** semi-finished products were two-fold bent, thermal joined, calibrated and pre-formed tubes. So far, a three-stage internal high-pressure forming process at room temperature plus two necessary intermediate heat treatments were used to produce the component. Due to its complexity as well as the limited forming ability of Titanium Grade 2 at room temperature an one step Hot Metal Gas forming was developed to replace the former procedure.

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Mechanical joining of materials with limited ductility: Analysis of process-induced defects

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AIP Conference Proceedings 2017年第1期1896卷

作者： M. Jäckel S. Coppieters M. Hofmann N. Vandermeiren D. Landgrebe D. Debruyne T. Wallmersberger K. Faes 1Fraunhofer Institute for Machine Tools and Forming Technology IWU (Dresden Germany) 2KU Leuven Technology Campus Ghent Department of Materials Engineering (Ghent Belgium) 3TU Dresden Institute for Solid Mechanics (Dresden Germany) 4Belgium Welding Institute (Ghent Belgium)

The paper shows experimental and numerical analyses of the clinching process of 6xxx series aluminum sheets in T6 condition and the self-pierce riveting process of an aluminum die casting. In the experimental investigations the damage behavior of the materials when using different tool parameters is analyzed. The focus of the numerical investigations is the damage prediction by a comparison of different damage criteria. Moreover, strength-and fatigue tests were carried out to investigate the influence of the joining process-induced damages on the strength properties of the joints.

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Modification of the process dynamics in micro-EDM by means of an additional piezo-control system

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AIP Conference Proceedings 2017年第1期1896卷

作者： M. Herzig T. Berger H.-P. Schulze M. Hackert-Oschätzchen O. Kröning A. Schubert 1Leukhardt Schaltanlagen Systemzechnik GmbH 39120 Magdeburg Germany 2Professorship Micromanufacturing Technology Faculty of Mechanical Engineering Chemnitz University of Technology 09107 Chemnitz Germany 3Fraunhofer Institute for Machine Tools and Forming Technology 09126 Chemnitz Germany

For the application of spark erosion in micro- and precision manufacturing, it is particularly important that small structures with small spark gaps can be machined in the range of a few micrometers. Due to the application of an additional high- dynamic piezo positioning system, smaller feed steps can be implemented which ensure a higher process stability. This additional feed system can be adapted to existing feed systems, whereby the process variable to be influenced is the spark gap. The primary feed system does not have to be directly influenced. The article shows how the structures of parallel regulation circuits for such operating piezo positioning systems are constructed and how they can improve the productivity, the machining accuracy and the surface quality. A selected example shows how the structural design of the highly dynamic system can be designed for different process parameters of industrial basic systems.

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