Universität Stuttgart

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Institute: search.filters.UBSInstitut.Fakultätsübergreifend / Sonstige EinrichtungAuthor: search.filters.author.Möhring, Hans-Christian

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    Evaluation of methods for measuring tool-chip contact length in wet machining using different approaches (microtextured tool, in-situ visualization and restricted contact tool)
    (2022) Ellersiek, Lars; Menze, Christian; Sauer, Florian; Denkena, Berend; Möhring, Hans-Christian; Schulze, Volker
    The contact length is one of the most important factors to evaluate the chip formation process and the mechanical loads in metal cutting. Over the years, several methods to identify the contact length were developed. However, especially for wet cutting processes the determination of the contact length is still challenging. In this paper, three methods to identify the contact length for dry and wet processes in cutting of Ti6Al4V and AISI4140 + QT are presented, discussed and analyzed. The first approach uses tools with a microtextured rake face. By evaluating the microstructures on the chip, a new method to identify the contact length is established. The second approach applies high speed recordings to identify the contact length. The challenge is thereby the application of high-speed recordings under wet conditions. In the third approach, tools with restricted contact length are used. It is shown that with all three methods the contact length is reduced using metal working fluid.
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    Flow visualisation and evaluation studies on metalworking fluid applications in manufacturing processes : methods and results
    (2023) Fritsching, Udo; Buss, Lizoel; Tonn, Teresa; Schumski, Lukas; Gakovi, Jurgen; Hatscher, Johnson David; Sölter, Jens; Avila, Kerstin; Karpuschewski, Bernhard; Gerken, Julian Frederic; Wolf, Tobias; Biermann, Dirk; Menze, Christian; Möhring, Hans-Christian; Tchoupe, Elio; Heidemanns, Lukas; Herrig, Tim; Klink, Andreas; Nabbout, Kaissar; Sommerfeld, Martin; Luther, Fabian; Schaarschmidt, Ingo; Schubert, Andreas; Richter, Markus
    Metalworking operations rely on the successful application of metalworking fluids (MWFs) for effective and efficient operation. Processes such as grinding or drilling often require the use of MWFs for cooling, lubrication, and chip removal. Electrochemical machining processes require electrolyte flow to operate. However, in those machining operations, a fundamental understanding of the mode of action of MWF is lacking due to the unknown flow dynamics and its interaction with the material removal during the process. Important information on the behaviour of MWFs during machining can be obtained from specific experimental flow visualisation studies. In this paper, promising flow visualisation analysis techniques applied to exemplary machining processes (grinding, sawing, drilling, and electrochemical machining) are presented and discussed. Shadowgraph imaging and flow measurements, e.g., particle image velocimetry, allow the identification of typical flow and MWF operating regimes in the different machining processes. Based on the identification of these regimes, efficient machining parameters and MWF applications can be derived. In addition, detailed experimental analyses of MWFs provide essential data for the input and validation of model development and numerical simulations within the Priority Programme SPP 2231 FluSimPro.
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    Assessment of the heat transfer conditions in the cavity of a rotating circular saw
    (2024) Stegmann, Jan; Baumert, Moritz; Kabelac, Stephan; Menze, Christian; Ramme, Johannes; Möhring, Hans-Christian
    To improve machining processes concerning the usage of lubricants, knowledge of the thermo-mechanical and thermo-fluid interactions at the cutting zone is of great importance. This study focuses on the description of the convective heat transfer which occurs during circular sawing when the lubricant is provided via an internal coolant supply. The highly complex flow field inside the cavity of the sawing process is separated into two distinct flow forms, an impingement and a channel flow. With the aid of experimental and numerical studies, the heat transfer characteristics of these two flow forms have been examined for water and a lubricant used in the circular sawing process. Studies have been conducted over a wide range of Reynolds numbers (impingement flow: 2×103
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    Cutting tool condition monitoring using eigenfaces : tool wear monitoring in milling
    (2022) König, Wolfgang; Möhring, Hans-Christian
    Effective monitoring of the tool wear condition within a machining process can be very challenging. Depending on the sensors used, often only a part of the relevant wear information can be detected. In the case of milling processes data acquisition is made even more difficult by the fact that the process working point is inaccessible for sensor applications due to the physical tool, the machining process itself, the chipping and used cooling-lubricants. By using a variety of sensors and different measuring principles, sensor data fusion strategies can counteract this problem. An approach to this is the eigenface algorithm. This approach, a face recognition technique, is tested for its suitability on tool condition monitoring in milling processes by using multi-sensor process data.