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New Publications

[ 1 ] Zanger, F.; Kacaras, A.; Neuenfeldt, P. & Schulze, V. (2019), "Optimization of the stream finishing process for mechanical surface treatment by numerical and experimental process analysis", CIRP Annals - Manufacturing Technology, pp. 373-376.
The stream finishing process represents an efficient mass finishing process capable in mechanical surface modification. In order to generate a deeper understanding of the cause-effect relationships, normal forces, material removal and surface topography were analyzed and correlated for varied process parameters of disc-shaped AISI 4140 specimens. Local resolution of tangential velocities of the particles and normal forces on the workpiece’s surface were simulated using the discrete element method for defined process parameter configurations and were correlated with experimental results. A deep process understanding is accomplished enabling the process design for efficient surface smoothing and improved residual stress depth distribution.

[ 2 ] Dackweiler, M.; Mayer, T.; Coutandin, S. & Fleischer, J. (2019), "Modeling and optimization of winding paths to join lightweight profiles with continuous carbon fibers", Production Engineering, no. 2, pp. 207-217. 10.1007/s11740-019-00914-2
A major challenge in composite manufacturing is to connect several fiber composite or hybrid profiles to a closed structure, since the conventional, metallic joining methods are often not applicable. An approach for joining such profiles is represented by the filament winding process, where the profiles are wrapped with carbon fibers. In order to achieve a flexibility in the joining process and a high reproducibility in deposition, a model for describing the winding paths was derived. An analytical model of the geometry of a T-joint is introduced in terms of a mathematical parametrization of areas. For the modeling of the winding paths itself, a differential-geometric approach combined with an algorithm to calculate geodesic and non-geodesic curves was used taking into account the relevant influencing parameters during winding. This model makes it possible to map different winding patterns of the profiles, which should serve as a starting basis for a kinematic simulation of the movements.

[ 3 ] Vargas, B.; Klose, J.; Zanger, F. & Schulze, V. (2019), "Simulative and Experimental Investigation of Gear Skiving with Reduced Axis Crossing Angles ". GETPRO, eds. Forschungsvereinigung Antriebstechnik e.V. (FVA), pp. 235-244.
Gear skiving has been increasingly used in the production of internal gears and shows high potential to manufacture external gears with adjacent shoulders. In order to avoid tool – workpiece collision, it is possible to minimize the length of tool overrun by reducing the axis crossing angle. However, the process kinematics changes with this reduction, representing a big challenge to the process design. In order to fulfill the lack of detailed knowledge and establish its industrial practice, simulative and experimental studies with axis crossing angles Σ between 5° and 15° were conducted. A three-dimensional kinematic simulation of gear skiving based on penetration calculation was carried out to demonstrate the influence of the process parameters on the local cutting conditions. The results show that the local rake angle reaches extremely negative values at the tooth tip of the cutting tool, which is usually characterized by the highest wear rates and therefore is critical for tool life. In order to relieve the local rake angles inherent to the unfavorable kinematics, both the tool geometry and the process can be optimized. Therefore, the simulations demonstrate how the constructional rake angle and the multiple infeed strategy can positively influence the local rake angle. In order to investigate how the local cutting conditions influence the cutting forces, wear behavior and tool life, tests with single-toothed tools were conducted for different axis crossing angles. The influence of the infeed strategy, tool rake angle and maximum uncut chip thickness on the local cutting conditions were investigated and different wear behaviors for axis crossing angles less than 10° were observed, suggesting a process limit regarding tool life. For smaller angles, the influence of the investigated parameters is very pronounced and the process design is limited to a narrow but still existing parameter window.

[ 4 ] Vargas, B.; Zapf, M.; Klose, J.; Zanger, F. & Schulze, V. (2019), "Numerical Modelling of Cutting Forces in Gear Skiving". Procedia CIRP 82, eds. Elsevier B.V., pp. 455-460.
Gear skiving is a high-performance machining process for gear manufacturing. Due to its complex kinematics, the local cutting conditions vary during tool engagement. Particularly, the local rake angle can reach highly negative values, which have a significant effect on the cutting force. In this paper, the Kienzle force model with additional coefficients was implemented in a numerical model to calculate local cutting forces considering the influence of local rake angle. The experimental validation based on total cutting forces shows good results and indicates an increase of model accuracy for a wide parameter range by considering the rake angle Variation.

[ 5 ] Wirth, F.; Hofmann, J. & Fleischer, J. (2019), "Einfluss geometrischer Materialtoleranzen auf die werkzeuggebundene Formgebung und Eigenschaften von Hairpin-Steckspulen", www.umformtechnik.net, pp. 1-18.
Toleranzbedingte Schwankungen des Kupferflachdrahtes stellen eine wichtige Einflussgröße bei der Formgebung von Hairpin-Steckspulen für die Fertigung elektrischer Traktionsmotoren dar. Im vorliegenden Beitrag werden die Wechselwirkungen geometrischer Toleranzen mit den charakteristischen Eigenschaften und der Konturgenauigkeit von Hairpin-Steckspulen durch analytische und numerische Methoden am Beispiel einer werkzeuggebunden Formgebung systematisch untersucht.

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