Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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  • Publication
    Automatic design and synthesis of control for a plug and play active vibration control module
    ( 2018)
    Uhlmann, E.
    ;
    Kushwaha, S.
    ;
    Mewis, J.
    ;
    Richarz, S.
    In this paper, a technique for automatic robust control design and synthesis for plug and play active vibration control module is presented. Robust control theory offers the uncertainty analysis and graphical manipulation of the frequency response as well as analytical solution approach. The prior knowledge of the plant model imposes limitations on the fast and effective implementation of the robust control. Moreover, the design of the weight functions for the robust control is usually a trial and error process. The plant identification and subsequent control design becomes even more tedious for modular devices with plug and play capability. In the present paper, the plant model is identified by using polyreference least square complex frequency estimator and an innovative automatic pole clustering algorithm. The HIF loop shaping robust control is designed, where the parameters of the weight functions are optimised using genetic algorithm. An experimental evaluation is also presented on a prototype modular structure.
  • Publication
    Substitution of Coolant by Using a Closed Internally Cooled Milling Tool
    ( 2017)
    Uhlmann, E.
    ;
    Riemer, H.
    ;
    Schröter, D.
    ;
    Sammler, F.
    ;
    Richarz, S.
    The saving of raw materials plays a major role in industry and is becoming increasingly important. In the field of cutting technology, the aim is to maximise practices such as the substitution of coolant and the steady increase of tool life in order to make an effective contribution towards environmental protection. Concerning the saving of coolant and to enhance the performance in dry machining a milling tool with a closed internally cooled system was developed. Heatpipes are applied which ensure improved heat dissipation from the cutting edge because of their excellent thermal conductivity. The dissipated heat is subsequently delivered to the surroundings via a heat sink. This contribution describes how the performance of a standard tool can be enhanced by the integration of a closed internally cooled system. Simulations of the heat distribution in the tool have been conducted to design and optimise the prototype. Hence, milling tests on duplex steel and temperature measurements in the cutting process have been carried out to verify and further optimise these simulation results.
  • Publication
    Twisted deep hole drilling tools for hard machining
    ( 2016)
    Uhlmann, E.
    ;
    Richarz, S.
    The availability of high performance twisted deep hole drilling tools has been a significant innovation achieved some years ago. The use of these tools in machining centres permits substantially higher productivity and flexibility compared to existing deep hole drilling tools or alternative manufacturing processes for holes with a high aspect ratio. The aim of the present work is the systematic consideration of twisted deep hole drilling tools for reliable and economical hard cutting operations with a high level of quality assurance. In particular, a detailed analysis of manufacturing flaws and tolerances in tool making as well as their influences on the tools performance and the dynamic process behaviour has been conducted. It is shown that twisted deep hole drilling tools can be successfully applied not only with a high productivity but also for a high quality production of hardened components. A prerequisite to this, however, are holistic and precisely controlled process steps including appropriate clamping devices and a suitable high pressure lubrication strategy as well as the availability of high performance tools manufactured with high precision and low tolerances. In this context the symmetry of the tool shown to be of vital importance for the tools performance and the quality of the drilled holes.
  • Publication
    Machining of Carbon and Glass Fibre Reinforced Composites
    ( 2016)
    Uhlmann, E.
    ;
    Sammler, F.
    ;
    Richarz, S.
    ;
    Reucher, G.
    ;
    Hufschmied, R.
    ;
    Frank, A.
    ;
    Stawiszynski, B.
    ;
    Protz, F.
    The combination of carbon and glass fibres in new reinforced composite components makes the machining of these promising materials challenging. The abrasive carbon and glass fibres cause tool wear and cutting edge rounding which results in higher process forces and insufficient workpiece quality. At the IWF, innovative process strategies for the machining of these materials have been developed, combining these with new cutting tool geometries. Furthermore, the classification of workpiece quality for reinforced plastic components has not been sufficiently addressed thus far and is also a focus of the work being undertaken. In order to adequately describe the workpiece quality, fibre pull-out and fibre protrusion must both be analysed. Using the example of a carbon and glass fibre composite material, the dependency of these characteristic quality parameters on process and tool parameters shall be analysed. The work described here compares an axial drilling with an helical milling process from both a technological (workpiece quality) and an economical (processing time) point of view.
  • Publication
    Machining of carbon fibre reinforced plastics
    ( 2014)
    Uhlmann, E.
    ;
    Sammler, F.
    ;
    Richarz, S.
    ;
    Heitmüller, F.
    ;
    Bilz, M.
    The implementation of carbon fiber reinforced plastics (CFRPs) in the aeronautical industry has increased dramatically in recent years due to their favourable combination of low weight and high strength as well as the adaptability of their material properties. In order to economically and reproducibly machine these materials with high part qualities, improvements in machining strategies must be made. The focus of this paper lies on innovative technologies for the machining of CFRPs whereby CVD diamond coated tools and milling tools for the improvement of milling processes have been designed. Furthermore, water jet cutting, CO2 jet cutting and grinding of CFRPs has been investigated. The quality of the machined workpieces is also an issue which requires addressing, particularly in relation to the fraying of machined edges. An innovative quantitative method for the evaluation of the workpiece quality of CFRP is presented.
  • Publication
    Smarte Werkzeuge für harte Werkstoffe
    ( 2012)
    Roeder, M.
    ;
    Uhlmann, E.
    ;
    Richarz, S.
    ;
    Fürstmann, P.
  • Publication
    Zerspanung von Titanmatrix-Verbundwerkstoffen
    ( 2012)
    Uhlmann, E.
    ;
    Roeder, M.
    ;
    Richarz, S.
  • Publication
    Vollhartmetall-Schaftfräser für die Hartbearbeitung über 65 HRC
    ( 2011)
    Uhlmann, E.
    ;
    Richarz, S.
    ;
    Sattel, S.
    Im Werkzeug- und Formenbau sowie in der Automobilindustrie liegen Bauteile aufgrund hoher Einsatzbelastungen oft im gehärteten Zustand vor. In Zusammenarbeit mit dem Institut für Werkzeugmaschinen und Fabrikbetrieb (IWF) der TU Berlin hat der Werkzeugspezialist Gühring praxisgerechte Werkzeuglösungen untersucht, um die etablierte Prozesskette zu verkürzen.
  • Publication
    Hartdrehen von PM-Schnellarbeitsstahl
    ( 2011)
    Uhlmann, E.
    ;
    Richarz, S.
    ;
    Fuentes, J.
  • Publication
    Substrate pre-treatment of cemented carbides using abrasive flow machining and laser beam ablation
    ( 2009)
    Uhlmann, E.
    ;
    Richarz, S.
    ;
    Mihotovic, V.
    A significant driver in research activities of manufacturers and university institutions is the improvement of tool life for cutting tools. Recent publications have shown that the substrate pre-treatment prior to coating as well as defined rounding of cutting edges are key factors for cutting tool life. Different technologies are used for substrate pre-treatment, depending on the machining task, flexibility of the process and economic aspects. However regarding the surface quality two opposing requirements come into conflict. While high surface quality supports the chip removal during machining, the film adhesion between substrate and coating is greater on rough surfaces. This paper presents a comparison of the abrasive flow machining (AFM) and laser ablation technologies as pre-treatment processes for cemented carbides. With respect to the relevant processing parameters, the effects of a pre-treatment using AFM and laser ablation on roughness, surface topography, mechanical activation and chemical composition have been determined.