Development, analysis and application of an actuated variable tool electrode for die-sinking EDM - VariSink4EDM

• Applicants: Professor Dr.-Ing. Jürgen Maas; Professor Dr.-Ing. Eckart Uhlmann
• Subject Area: Joining and Separation Technology ; Production Automation and Assembly Technology
• Term: since 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 426311818

Electrical discharge machining (EDM) is a key technology in the tool and mold making industry, since materials with high hardness and mechanical resistance are machinable and accuracies in the micrometer range can be achieved. The tool electrodes in sinking EDM have complex geometries that are manufactured by milling, which results in a high cost and time expenditure. To fabricate the final contour in the workpiece, numerous tool electrodes are required due to tool electrode wear. The manufacturing of the tool electrodes is often more time consuming than the actual EDM process. The goal of the first research period was to provide basic knowledge about a variably actuated tool electrode module, which is used for roughing processes in EDM. This module consists of 25 square tool electrode segments, which are connected by force-fit couplings to linear actuators. These linear actuators enable to adjust the geometry of the tool electrode module. In addition, the actuated tool electrode segments can be positioned dynamically, which allows novel flushing strategies via transverse wave movements of the tool electrode module. A flushing effect by actuated transverse wave movements has been proven experimentally. Based on the project results, three main goals were derived for the second funding period. First, obtaining advanced knowledge of the actuated tool electrode module during the EDM process. This includes analyses about the influence of electromagnetic fields on the actuators and sensors of the tool electrode module, the electrical and thermal behavior of the coupling between the tool electrode segments and the actuator slider, as well as new control concepts to generate multidimensional transverse waves. Secondly, validated self-sensing methods will be provided to estimate the slider positions of the linear actuators and the seismic mass of the tool electrode segments. Based on that, the local tool electrode wear during the process can be determined. Third, analyses of novel transverse wave flushing strategies in the process are provided. For this purpose, excitation profiles for the tool electrode segments are examined in flow simulations to generate directed fluid movements which then are analyzed experimentally and validated in the process. At the end of the second research period, a variably actuated tool electrode module is available for online self-sensing of the tool electrode wear. Novel flushing strategies through transverse waves have been validated to optimize the removal rate and tool electrode wear in the EDM process.

• DFG Programme: Research Grants