Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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Safety of slim tool extensions for milling operations

2019 , Uhlmann, E. , Thom, S. , Barth, E. , Pache, T. , Prasol, L.

The development of 5-axis machine tools (MT) allows complete machining of complex workpiece geometries. In order to counteract lacking operation space and to improve the accessibility of the workpiece, slim tool extensions (STE) are applied. Operating errors, e.g. by crash, can cause plastic deformation of STE during machining operation and therefore lead to an increased moment of inertia, and thus to rotational energy due to the spindle speed control of machine tools. Currently applied machine tool enclosures are not designed for such failures with corresponding kinetic energies EKIN. The described failure implies a risk potential for operators and a high damage potential for machine tools. In this paper, the failure scenario is identified and modeled. This includes the calculation of elastoplastic deformations of STE based on finite element analysis and analytical calculation of kinetic energies EKIN considering deformed STE. Based on the described model a parameter study is carried out considering the geometry of the STE as well as the spindle speed nS. The safety of existing machine tool enclosures is evaluated according to DIN EN 12417 in order to identify safe operating conditions. Finally, the authors suggest possible solutions addressing both, the STE and machine tool enclosure. The research presented in this paper is funded by the German Machine Tool Builders Association (VDW).

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CVD-Diamantwerkzeuge mit SiC-Zwischenschicht

2019 , Uhlmann, E. , Barth, E. , Gäbler, J. , Höfer, M.

Der Cobalt-(Co)-Anteil in Hartmetallen diffundiert während des Diamantbeschichtungsprozesses in die Diamantschicht und mindert deren Haftfähigkeit. Siliciumcarbid-(SiC)-Zwischenschichten können als Diffusionsbarriere für Cobalt dienen und die konventionelle Ätzvorbehandlung der Substrate ersetzen. Im Rahmen einer Forschungsarbeit werden Beschichtungsprozesse mit SiC-Zwischenschicht entwickelt, diese Schichtsysteme auf verschiedene Substrate aufgebracht und durch Zerspanungsuntersuchungen bewertet.

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Smoothed Particle Hydrodynamics simulation of the machining process of Inconel 718

2018 , Uhlmann, E. , Barth, E.

The Smoothed Particle Hydrodynamics (SPH) is a meshfree simulation method which allows to describe the machining process of the nickel-based alloy Inconel 718. This paper analyses the accuracy of a developed simulation model for an orthogonal turning process. The simulation results show the occurring process forces. Subsequently, the model is extended with a variable chip thickness to consider the different engagement condition during a peripheral down milling process. The model allows to investigate the influence of geometry parameters of the cutting edge for possible tools designs with little economic and financial expenses.

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