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 Simulation study on single-lip deep hole drilling using design of experiments(2021) Fandino, Daniel; Guski, Vinzenz; Wegert, Robert; Möhring, Hans-Christian; Schmauder, SiegfriedSingle-lip deep hole drilling (SLD) is characterized by a high surface quality and compressive residual stress in the subsurface of the drill hole. These properties are strongly dependent on the cutting parameters of the SLD process and the actual geometry of the insert and the guide pads. In the present work, full 3D FE simulations of the SLD process were carried out to analyze the thermo-mechanical as-is state in the drilling contact zone by evaluating the feed force, the temperature, as well as the residual stress in the drill hole subsurface. An extensive simulation study was conducted on the effect of the process parameters on the properties using design of experiments (DoE). For the simulations, the Johnson-Cook (JC) constitutive law and the element elimination technique (EET) were applied to represent the material behavior of the workpiece, including chip formation. In-process measurements as well as results from the hole-drilling method to determine residual stresses were conducted to verify the numerical results. By means of DoE and analysis of variance (ANOVA), regression models were developed to describe the effect of the feed rate, cutting speed, and guide pad height on the temperature, feed force, and residual stress in the subsurface.Item Open Access Ermittlung des Späneauswurfs aus dem Werkzeug und Dokumentation des Spanflugverhaltens im Spanraum(2000) Scheurich, HeikoNach einem kurzen Einblick in den derzeitigen Forschungsstand im Bereich der Partikelabsaugung und Spanentsorgung als Einleitung, bilden die daran anschließend beschriebenen grundlegenden theoretischen Einflußgrößen in diesem Bereich der experimentellen Forschung eine Überleitung zur Problemstellung. Um die Ermittlung des Spanaustritts aus dem Werkzeug und die Dokumentation des Spanflugverhaltens im Spanraum zu erreichen, wurde ein Versuchsaufbau konstruiert und realisiert, dessen Details dann genauer dargelegt und beschrieben werden. Anhand einer genauen Beschreibung des Versuchsablaufes kann eine Versuchsreihe nachvollzogen werden. Die exakten Ergebnisse der Versuche werden im Anschluß an die Erläuterungen der Versuchsdurchführung zum einen durch die Darstellung der prozentualen Spangrößenverteilung und der realen Gewichtsverteilung in den jeweiligen Fächern der Aufnehmer in Diagrammen und zum anderen durch die Dokumentation mittels geeigneter Bildreihen aus Aufnahmen des Zerspanungsprozesses mit einer Hochgeschwindigkeitskamera dargestellt. Durch die Gegenüberstellung aller Ergebnisse der Bearbeitung von Buche, Fichte, Spanplatte und MDF mit den beiden Versuchswerkzeugen erfolgt eine Einordnung der Effizienz der Versuchsreihen. Daran anschließend führt die theoretische Auswertung zu Ansätzen einer rechnerischen Ermittlung der Spanflugbahn im Spanraum. Abschließend wird der noch bestehende Forschungsbedarf in dieser Problemstellung diskutiert.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 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 Staubausbreitungsuntersuchung in einer Messkabine nach DIN 33891(2000) Stahl, MarkusDie vorliegende Arbeit - Staubausbreitungsuntersuchung in einer Messkabine nach DIN 33891 - ist Teil eines EU-Projekts zur Normung von Staubmessungen bei Emission durch Elektrowerkzeuge. Zielsetzung des Projektes ist es, eine Basis zu schaffen, um Staubmessungen zukünftig im Kanal einer Messkabine nach DIN 33891 durchführen zu können. Dafür muss der Zusammenhang zwischen der erfassten Staubmasse im Messkanal und der in der Kabine ausgebrachten Staubmasse bekannt sein. In den durchgeführten Versuchen werden vier verschiedene Aerosole aus vorgegebenen Stäuben in der Kabine ausgebracht. Dies geschieht jeweils in drei unterschiedlichen Höhen. Darüber hinaus werden die Messungen mit zwei verschiedenen Absauggeschwindigkeiten durchgeführt. Im Hinblick auf die Entwicklung eines optimierten Staubmessverfahrens werden die Ergebnisse abschließend dargestellt und diskutiert.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 Glass fracture during micro-scratching(2020) Zakiev, Islam; Gogotsi, George A.; Storchak, Michael; Zakiev, VadimThe regularity of glass surface fracture and resistance to destruction were investigated by the methods of progressive and static microscratching with the Berkovich indenter. The research hardware was the original nanoindentation/microscratching devices and a non-contact interference profilometer for studying the morphology of the formed microscratches. The regularities of the fracture stages and the cracks growth along the microscratch were established depending on the indenter applied load. Based on analysis of the microcracks profile formed at various loads on the indenter immediately after the process of applying these scratches and after several hours of rest, it was found that the process of crack propagation along the scratch continues for a long time. Taking into account this established fact, a discrete-statistical method of the cracks formation for a long time is proposed. In accordance with this method, scratching is carried out with a constant load on short and separated tracks. The load on the indenter in each track increases discretely with a certain step. The influence of the medium on the scratching process is analyzed. The breaking mechanism in the glasses scratching process is formulated as the load on the indenter increases, and a model of the glass fracture stages is proposed.Item Open Access 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, VolkerThe 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.Item Open Access A data-driven approach for cutting force prediction in FEM machining simulations using gradient boosted machines(2024) Reeber, Tim; Wolf, Jan; Möhring, Hans-ChristianCutting simulations via the Finite Element Method (FEM) have recently gained more significance due to ever increasing computational performance and thus better resulting accuracy. However, these simulations are still time consuming and therefore cannot be deployed for an in situ evaluation of the machining processes in an industrial environment. This is due to the high non-linear nature of FEM simulations of machining processes, which require considerable computational resources. On the other hand, machine learning methods are known to capture complex non-linear behaviors. One of the most widely applied material models in cutting simulations is the Johnson-Cook material model, which has a great influence on the output of the cutting simulations and contributes to the non-linear behavior of the models, but its influence on cutting forces is sometimes difficult to assess beforehand. Therefore, this research aims to capture the highly non-linear behavior of the material model by using a dataset of multiple short-duration cutting simulations from Abaqus to learn the relationship of the Johnson-Cook material model parameters and the resulting cutting forces for a constant set of cutting conditions. The goal is to shorten the time to simulate cutting forces by encapsulating complex cutting conditions in dependence of material parameters in a single model. A total of five different models are trained and the performance is evaluated. The results show that Gradient Boosted Machines capture the influence of varying material model parameters the best and enable good predictions of cutting forces as well as deliver insights into the relevance of the material parameters for the cutting and thrust forces in orthogonal cutting.