Investigation of Advanced Control Schemes for High-speed Small-Hole EDM Drilling

High-speed small-hole electrical discharge machining (EDM) drilling is extensively applied to machine cooling film holes of turbine blades and diesel nozzle spray holes due to its non-contact characteristics and dedicated features, e.g. high-speed rotation and high-frequency pulse power generator. However, with increasing drilling depth, the process stability could be easily deteriorated by frequent debris due to restricted flushing conditions. Consequently, the machining efficiency and surface finish of high-aspect-ratio holes cannot be guaranteed. To address this problem, this paper proposes a sliding mode and self-tuning control scheme to regulate the discharging process. An integral function is presented as the switch mode to avoid chattering, and a direct algorithm that reparameterizes the model in terms of controller parameters is considered to reduce computation. The presented comparative drilling experiments with high aspect ratio (nearly 100) show the benefits of the adaptive controller.

Publication year:2021

Accessibility:Open