Development and application of novel tool electrodes with external flushing channels to increase the economic efficiency of EDM drilling
Final Report Abstract
The overarching goal of the research project was the development of innovative tool electrodes for electrical discharge drilling. This was to be achieved through the identification and implementation of optimal geometries for externally located flushing channels. Systematic analyses confirmed that external flushing channels improve flushing conditions in the working gap s, particularly for drilling with high aspect ratios φ. For two cross-sectional geometries in V- and U-shapes, regression equations were derived to mathematically describe the influence of geometric parameters such as groove width bN, number of grooves N or the groove angle αg on the target process variables of material removal rate V̇ W, tool wear ϑ, conicity α and the lateral working gap sL. These models enable a tailored adjustment of flushing channel geometries. In addition to the dominant influence of flushing pressure pf, which mitigates the effects of geometric adjustments, it was found that each flushing channel geometry has an individual operating point of flow-related variables such as rotational speed n and flushing pressure pf to efficiently evacuate debris from the drilling process. Measurements and simulations provided previously unknown insights into the high-frequency phenomena in the working gap s and the evacuation of debris. High-speed cameras, signal analyses, and synchronized recordings of feed velocity vf and process signals were utilized for this purpose. An automated signal analysis software supports process-related evaluation in streaming mode. The derivation of process-improving flushing channel geometries and the development of innovative tool electrodes for high-aspect-ratio φ drilling were successful.
Publications
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Novel Advances in Machine Tools, Tool Electrodes and Processes for High-Performance and High-Precision EDM. Procedia CIRP, 113, 611-635.
Uhlmann, Eckart; Polte, Mitchel & Yabroudi, Sami
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Echtzeit-Energieüberwachung in der Funkenerosion/Real-time energy monitoring in electrical discharge machining – Advanced software practices for signal analysis and classification. wt Werkstattstechnik online, 113(07-08), 304-310.
Uhlmann, Eckart; Polte, Mitchel; Yabroudi, Sami; Thißen, Kai & Penske, Wilhelm
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Helical Electrodes for Electro-Discharge Drilling: Experimental and CFD-Based Analysis of the Influence of Internal and External Flushing Geometries on the Process Characteristics. Journal of Manufacturing and Materials Processing, 7(6), 217.
Uhlmann, Eckart; Polte, Mitchel; Yabroudi, Sami; Gerhard, Nicklas; Sakharova, Ekaterina; Thißen, Kai & Penske, Wilhelm
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Localization of Discharges in Drilling EDM Through Segmented Workpiece Electrodes. Lecture Notes in Production Engineering, 209-218. Springer International Publishing.
Thißen, K.; Yabroudi, S. & Uhlmann, E.
