07 Fakultät Konstruktions-, Produktions- und Fahrzeugtechnik
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/8
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Item Open Access Numerical modeling of cutting characteristics during short hole drilling : modeling of kinetic characteristics(2023) Storchak, Michael; Stehle, Thomas; Möhring, Hans-ChristianAnalyzing the cutting process characteristics opens up significant opportunities to improve various material machining processes. Numerical modeling is a well-established, powerful technique for determining various characteristics of cutting processes. The developed spatial finite element model of short hole drilling is used to determine the kinetic characteristics of the machining process, in particular, the components of cutting force and cutting power. To determine the component model parameters for the numerical model of drilling, the constitutive equation parameters, and the parameters of the contact interaction between the drill and the machined material on the example of AISI 1045 steel machining, the orthogonal cutting process was used. These parameters are determined using the inverse method. The DOE (Design of Experiment) sensitivity analysis was applied as a procedure for determining the component models parameters, which is realized by multiple simulations using the developed spatial FEM model of orthogonal cutting and the subsequent determination of generalized values of the required parameters by finding the intersection of the individual value sets of these parameters. The target values for the DOE analysis were experimentally determined kinetic characteristics of the orthogonal cutting process. The constitutive equation and contact interaction parameters were used to simulate the short hole drilling process. The comparison of experimentally determined and simulated values of the kinetic characteristics of the drilling process for a significant range of cutting speed and drill feed changes has established their satisfactory coincidence. The simulated value deviation from the corresponding measured characteristics in the whole range of cutting speed and drill feed variation did not exceed 23%.Item Open Access Driving profiles of light commercial vehicles of craftsmen and the potential of battery electric vehicles when charging on company premises(2024) Heilmann, Oliver; Bocho, Britta; Frieß, Alexander; Cortès, Sven; Schrade, Ulrich; Casal Kulzer, André; Schlick, MichaelThis paper examines the extent to which it is possible to replace conventional light commercial vehicles in the heating, ventilation and air conditioning and plumbing trade with battery electric vehicles with an unchanged usage profile. GPS trackers are used to record the position data of 22 craft vehicles with combustion engines from eleven companies over the duration of one working week. Within this paper, various assumptions (battery capacity and average consumption) are made for battery electric vehicles and the charging power on the company premises. The potential of battery electric vehicles is evaluated based on the assumption that they are charged only on company premises. Using the collected data and the assumptions made, theoretical state of charge curves are calculated for the vehicles. The driving profiles of the individual vehicles differ greatly, and the suitability of battery electric vehicles should be considered individually. Battery capacity, vehicle energy consumption and charging power at the company have a substantial influence on the suitability of battery electric vehicles. Furthermore, there are differences between vehicles that can charge on the company premises at night and those that cannot or can only do so on some days.Item Open Access Generation of mechanical characteristics in workpiece subsurface layers through milling(2024) Storchak, Michael; Hlembotska, Larysa; Melnyk, OleksandrThe generation of mechanical characteristics in workpiece subsurface layers as a result of the cutting process has a predominant influence on the performance properties of machined parts. The effect of the end milling process on the mechanical characteristics of the machined subsurface layers was evaluated using nondestructive methods: instrumented nanoindentation and sclerometry (scratching). In this paper, the influence of one of the common processes of materials processing by cutting-the process of end tool milling-on the generation of mechanical characteristics of workpiece machined subsurface layers is studied. The effect of the end milling process on the character of mechanical property formation was evaluated through the coincidence of the cutting process energy characteristics with the mechanical characteristics of the machined subsurface layers. The total cutting power and cutting work in the tertiary cutting zone area were used as energy characteristics of the end milling process. The modes of the end milling process are considered as the main parameters affecting these energy characteristics. The mechanical characteristics of the workpiece machined subsurface layers were the microhardness of the subsurface layers and the total work of indenter penetration, determined by instrumental nanoindentation, and the maximum depth of indenter penetration, determined by sclerometry. Titanium alloy Ti10V2Fe3Al (Ti-1023) was used as the machining material. Based on the evaluation of the coincidence of the cutting process energy characteristics with the specified mechanical characteristics of the machined subsurface layers, the milling mode effect of the studied titanium alloy, in particular the cutter feed and cutting speed, on the generated mechanical characteristics was established.Item Open Access Local laser heat treatment of AlSi10Mg as-built parts produced by Laser Powder Bed Fusion(2024) Kramer, Steffen; Jarwitz, Michael; Schulze, Volker; Zanger, FrederikToday, complex structural components for lightweight applications are frequently manufactured by laser powder bed fusion (PBF-LB), often using aluminum alloys such as AlSi10Mg. However, the application of cyclic load cases can be challenging as PBF-LB produced AlSi10Mg parts typically have low ductility and corresponding brittle failure behavior in the as-built condition. Therefore, this paper presents investigations on the feasibility of a laser heat treatment of PBF-LB produced AlSi10Mg parts to locally increase the ductility and decrease the hardness in critical areas. Potential heat treatment process parameters were derived theoretically based on the temperature fields in the material calculated assuming three-dimensional heat conduction and a moving heat source. PBF-LB produced specimens were then laser heat treated at varying laser power and scan speed. Hardness measurements on metallographic cross sections showed hardness reductions of over 35 % without inducing hydrogen pore growth.Item Open Access Generalizable process monitoring for FFF 3D printing with machine vision(2023) Werkle, Kim Torben; Trage, Caroline; Wolf, Jan; Möhring, Hans-ChristianAdditive manufacturing has experienced a surge in popularity in both commercial and private sectors over the past decade due to the growing demand for affordable and highly customized products, which are often in direct opposition to the requirements of traditional subtractive manufacturing. Fused Filament Fabrication (FFF) has emerged as the most widely-used additive manufacturing technology, despite challenges associated with achieving contour accuracy. To address this issue, the authors have developed a novel camera-based process monitoring method that enables the detection of errors in the printing process through a layer-by-layer comparison of the actual contour and the target contour obtained via G-Code processing. This method is generalizable and can be applied to different printer models with minimal hardware adjustments using off-the-shelf components. The authors have demonstrated the effectiveness of this method in automatically detecting both coarse and small contour deviations in 3D-printed parts.Item Open Access An exploratory analysis of the current status and potential of service-oriented and data-driven business models within the sheet metal working sector : insights from interview-based research in small and medium-sized enterprises(2024) Wirth, Jonas; Schneider, Mirko; Hanselmann, Leon; Fink, Kira; Nebauer, Stephan; Bauernhansl, ThomasResponding to changing value creation processes in the sheet metal working sector, where the complexity and interchangeability of products challenge traditional differentiation strategies, this exploratory analysis examines the integration of service-oriented and data-driven business models as new paths to ensure competitiveness, especially for small and medium-sized enterprises (SMEs). This study aims to capture the current state and challenges associated with the implementation of these business models in this sector. This research was conducted through semi-structured interviews with SMEs in the industry. The findings indicate that service-oriented and data-driven business models are not yet widely adopted and that manufacturing companies require support in their implementation. Fields of action were identified for the industry. These are “Creating awareness and understanding”, “Recognizing added value”, “Increasing company maturity”, and “Understanding the change process”. Cooperation between science and industry is essential in tackling these fields of action to ensure the successful integration of such business models in manufacturing companies. This paper identifies challenges in the fields of action that companies must address through a structured approach, promoting awareness, recognizing value, improving organizational maturity, and understanding the change process to successfully implement service-oriented and data-driven business models.Item Open Access Untersuchung adhäsiver Fügeverfahren zur Herstellung hartmetallbestückter Verbundkreissägeblätter(Stuttgart : Fraunhofer-Institut für Produktionstechnik und Automatisierung IPA, 2025) Stroka, Michael; Bauernhansl, Thomas (Univ.-Prof. Dr.-Ing.)Das Ziel dieser Arbeit ist es, die Einsatzfähigkeit der Klebtechnik für Verbundkreissägeblätter für die Bearbeitung von Holz(werk)- und Kunststoffen sowie Aluminium zu untersuchen. Durch den Einsatz des wärmearmen Klebens ergibt sich die Möglichkeit, neue Schneidstoffe oder bereits geschliffene und beschichtete Hartmetallzähne anzuwenden. Weiter wird das Stammblatt thermisch weniger beeinflusst, wodurch der Nacharbeitsaufwand reduziert werden kann. Anhand von experimentellen Sägeversuchen werden die mechanischen Anforderungen in Form der Schnittkräfte und damit die resultierende Beanspruchung in der Fügestelle ermittelt. Diese Randbedingungen werden bei der Auswahl möglicher Klebstoffe und Oberflächenbehandlungen berücksichtigt. Durch zerstörende Prüfung geklebter Proben werden die Einflüsse der Klebstoffe und Oberflächenbehandlungen auf die Festigkeit untersucht und geeignete Kombinationen abgeleitet. Die Entwicklung einer Automatisierungstechnik im Labormaßstab führt die Arbeit fort. Eine Betrachtung des technologischen und wirtschaftlichen Potenzials geklebter Ver-bundkreissägeblätter sowie die Erarbeitung eines Optimierungsansatzes zur Spannungsreduzierung in der Klebfuge mittels FE-Methoden schließen die Arbeit ab. Die Versuche haben gezeigt, dass mit Hilfe eines einkomponentigen Epoxidharzklebstoffs und Korund sowie lasergestrahlten Zähnen einsatzfähige Klebverbindungen realisiert werden können, welche sowohl dem Schleifen als auch einem Zerspanversuch standhalten. Durch die entwickelte Automationslösung kann eine hohe Reproduzierbarkeit der Klebfestigkeit erzielt werden. Die FE-Analysen zeigen, dass die Beanspruchung in der Klebung durch angepasste Geometrien der Zahnsitze reduziert werden können. Der Vergleich der Herstellkosten des Fügeprozesses für ein Werkzeug zeigen, dass ein hohes Potenzial für einen wirtschaftlichen Einsatz besteht, wenn die gesamte Prozesskette umgestaltet wird. Dies wird erst durch den Wechsel der Fügetechnologie von Löten auf Kleben ermöglicht.Item Open Access Plasticity resource of cast iron at deforming broaching(2023) Nemyrovskyi, Yakiv; Shepelenko, Ihor; Storchak, MichaelThe contact interaction mechanics of deformation broaching in low-plasticity materials is studied. Particular attention is paid to the study of the stress–strain state parameters and the plasticity margin in the deformation zone during the machining of gray cast iron EN-GJL-200. The stress-strain state was analyzed using a finite-element model of the deforming broaching process for each area of the deformation zone. The model parameters of the machined material were determined experimentally by compressing specimens of gray cast iron EN-GJL-200. The changes in the parameters of accumulated strain, stress tensor components, stress triaxiality ratio, hydrostatic stress, and plasticity margin at different deformation zones along the machined specimen depth are analyzed. It is shown that there is a zone of local plastic deformation in conditions of critical contact stresses. This leads to the appearance of tensile stresses that reduce the plasticity margin in the surface layer. The impact of tool geometry on the stress–strain state of the surface layer is also discussed, and recommendations for the optimal working angle of the deforming element are provided based on plasticity margin minimization.Item Open Access A 10 V transfer standard based on low-noise solid-state Zener voltage reference ADR1000(2024) Bülau, André; Walter, Daniela; Zimmermann, AndréVoltage standards are widely used to transfer volts from Josephson voltage standards (JVSs) at national metrology institutes (NMIs) into calibration labs to maintain the volts and to transfer them to test equipment at production lines. Therefore, commercial voltage standards based on Zener diodes are used. Analog Devices Inc. (San Jose, CA, USA), namely, Eric Modica, introduced the ADR1000KHZ, a successor to the legendary LTZ1000, at the Metrology Meeting 2021. The first production samples were already available prior to this event. In this article, this new temperature-stabilized Zener diode is compared to several others as per datasheet specifications. Motivated by the superior parameters, a 10 V transfer standard prototype for laboratory use with commercial off-the-shelf components such as resistor networks and chopper amplifiers was built. How much effort it takes to reach the given parameters was investigated. This paper describes how the reference was set up to operate it at its zero-temperature coefficient (z.t.c.) temperature and to lower the requirements for the oven stability. Furthermore, it is shown how the overall temperature coefficient (t.c.) of the circuit was reduced. For the buffered Zener voltage, a t.c. of almost zero, and with amplification to 10 V, a t.c. of <0.01 µV/V/K was achieved in a temperature span of 15 to 31 °C. For the buffered Zener voltage, a noise of ~584 nVp-p and for the 10 V output, ~805 nVp-p were obtained. Finally, 850 days of drift data were taken by comparing the transfer standard prototype to two Fluke 7000 voltage standards according to the method described in NBS Technical Note 430. The drift specification was, however, not met.Item Open Access Comparison of in-process laser drying with furnace and vacuum drying to reduce moisture of AlSi10Mg powder processed in Laser Powder Bed Fusion(2024) Lubkowitz, Victor; Fayner, Leonie; Kramer, Steffen; Schulze, Volker; Zanger, FrederikIn most powder bed-based laser melting systems (PBF-LB), metal powders must be handled without inertization but in an air atmosphere for a short time, increasing the AlSi10Mg powder moisture and reducing the achievable component density. Consequently, different drying methods were investigated. Drying in a furnace with an inert atmosphere, using a vacuum to evaporate the water at low temperatures, and vaporizing moisture layerwise from the spreaded powder with a defocused, low-power laser beam as a further process step of the PBF-LB process. Therefore, four different moisturized powders, which were dried with different settings for the drying methods, are analyzed. All drying methods reduce the moisture content of the powder, with in-process drying being the most effective. Due to the oxide layer growth around the particles during furnace and vacuum drying, the achievable sample density after drying is worse. In-process drying with low energy density is the best option to reach a reduction of hydrogen pores and an increase of density.