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New Publications

[ 1 ] Echsler Minguillon, F.; Schömer, J.; Stricker, N.; Lanza, G. & Duffie, N. (2019), "Planning for changeability and flexibility using a frequency perspective", CIRP Annals - Manufacturing Technology, vol. 1, pp. 427-430. https://doi.org/10.1016/j.cirp.2019.03.006
Changeability and flexibility are increasingly important features of production in today’s global environment. The influences of change drivers (e.g. fluctuating demand) lead to pressure for change in production systems, and various types of change can be applied. An approach for determining a cost-efficient plan for types of change by analyzing the demand from a frequency perspective is presented in this paper. The approach iteratively optimizes the allocation of types of change in the frequency domain and evaluates the obtained solution in the time domain. The result is improved decision support and increased transparency for planners in obtaining cost-efficiency and agility.

[ 2 ] Roth, S.; Pracisnore, F.; Coutandin, S. & Fleischer, J. (2020), "A new approach for modelling the fibre path in bolted joints of continuous fibre reinforced composites", Composite Structures, pp. 0-0. https://doi.org/10.1016/j.compstruct.2020.112184
A fibre conform hole forming into continuous fibre reinforced components leads to beneficial part properties, as the fibre structure is not damaged in comparison to a drilling operation due to a reorientation of the fibres during the preforming process. To determine precisely the local component properties of the manufactured composite part, detailed information about the resulting fibre paths is required. For the first time, this paper provides a universal methodology to approximate the actual fibre paths in the reoriented area around the hole. Based on a few experimental data, the developed framework allows the construction of the fibre pathways depending on the formed hole diameter and the used fabric type. Two models based on polynomial splines are developed and compared with regards to the achievable model accuracy. The overall methodology is evaluated using different hole diameter and fabric types. Here, a very good correlation between approximation and reality is observed.

[ 3 ] Lanza, G.; Klenk, F. & Krahe, C. (2019), "Track & Trace als Basis für die Kreislaufwirtschaft in der Automobilindustrie", Werkstoffe in der Fertigung, pp. 22-23.
Die Kreislaufwirtschaft zielt darauf ab, den aktuellen „take, make & dispose“-Ansatz der linearen Wirtschaft, der Auslöser massiver Ressourcenverschwendung ist, durch die mehrfache, wertschöpfende Zufuhr von Produkten in den Produktionsprozess zu verändern. Hierdurch kann der Ressourcen- und Energieverbrauch reduziert sowie die Wirtschaftlichkeit der Unternehmen erhöht werden. Eine Voraussetzung für die Implementierung der Kreislaufwirtschaft ist die lückenlose Nachverfolgbarkeit von Produkten, Komponenten und Materialien. So wird ermöglicht, dass Produkte, die am Ende ihres Lebenszyklus wieder in den Besitz eines Unternehmens gelangen, leichter identifiziert, aufgearbeitet und weiterverwendet werden können. Der vorliegende Artikel zielt darauf ab, eine Übersicht aktueller Track & Trace-Technologien zu geben und die Möglichkeiten aufzuzeigen, wie mittels einer zentralen Austauschplattform ein Mehrwert aus Daten generiert werden kann.

[ 4 ] Mayer, D.; Hausmann, L.; Maul, N.; Reinschmidt, L.; Hofmann, J. & Fleischer, J. (2019), "Systematic investigation of the grooving process and its influence on slot insulation of stators with hairpin technology". 9th International Electric Drives Production Conference (E|DPC) - Proceedings, eds. IEEE, pp. 161-167.
Due to the increasing electrification of the automotive drive train, production systems for electric motors grow in importance. In order to produce the required quantities at reasonable costs there is a particular need for developing new stator production plants. A trend towards using shaped coils in stators, so called hairpins, is emerging as this technology promises great automation potentials as well as high copper fill factors. Due to the axial insertion of the hairpins into the lamination stack the requirements for the slot liner shape change in contrast to the widely used winding technologies. Thus, new slot liner shapes, such as ‘B’-, ‘O’- or ‘S’-shapes, can be used. The shapes replace the previous ‘U’- shaped slot liner as well as the slot cover. In order to maintain a high fill factor, the shapes have to fit closely to the lamination stack. For this purpose, the insulation paper must be grooved and then folded into the desired shape. To map the new slot liner shapes, the grooving process and its influence on slot insulation must be understood in detail. In this paper the grooving process and its effect on breakdown voltage of the slot liner are examined. First, an overview about different insulation materials for slot liners is given. Second, a test rig setup to adjust different depths and widths of grooving is introduced. Additionally, a further test rig setup for conducting breakdown voltage tests on slot liners is presented. Based on these test rigs, experiments are carried out to determine how the grooving process parameters affect the breakdown voltage of the slot liners. As a result of the investigation a characterization of the grooving process regarding the breakdown voltage for the examined insulation paper is presented.

[ 5 ] Wößner, W.; Uhl, E.; Hofmann, J. & Fleischer, J. (2019), "Sensitivity Analysis and Validation of the Intelligent Assembly Process for Permanent Magnet Rotors with the Balancing Grade G 2.5". 2019 9th International Electric Drives Production Conference (EDPC), eds. IEEE, pp. 15-20.
An increased range of electric vehicles not only sets high demand to the chosen concept for energy storage but also implies that electric motors with high power-to-weight ratio need to be employed. A possible approach for weight reduction in a permanent magnet synchronous machine is an intelligent assembly of the rotor components followed by a positive balancing process. This approach allows to predict and minimize the rotor unbalance, resulting in a reduction in size of balancing discs that can account for up to 10 % of the rotor mass. A higher potential in reduction of the rotor mass lies in the ability to dispense entirely with balancing discs and the subsequent balancing process. This paper analyses whether a balancing grade of G 2.5 can be achieved through intelligent assembly. In a first step, the required measuring and mounting steps are presented. Possible measuring and mounting uncertainties are identified and quantified through literature, simulation and experimental results, allowing a sensitivity analysis of the entire process chain. The results of this analysis are used to identify the measuring and mounting steps with the highest influence on the deviation between an expected and measured rotor unbalance. For magnet assembly, a good model validity is achieved. Errors in perpendicularity between lamination stacks and shafts are found to have a high influence on the reachable rotor unbalance and therefore offer room for further improvement of the approach.

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