METHOD FOR TWO-STAGE ELECTRO-EROSIVE-CHEMICAL PIERCING OF SMALL-DIAMETER HOLES Russian patent published in 2023 - IPC B23H9/14 B23H5/02 

FIELD: processing methods.

SUBSTANCE: drilling of holes in parts made of high-strength steels and alloys. In the method, current pulses are applied to the interelectrode gap at the piercing and finishing stages. At the first stage of piercing the holes, current pulses have a gentle leading edge with t_f>20 mcs, which is chosen in such a way as to initiate predominantly low-voltage electrical discharges in the end interelectrode gap. At the second stage of finishing, the side surface of the hole, the current pulses have a steep leading edge with t_f<10mcs, the parameters of which are selected in such a way that during the action of the current pulse, the electrolyte in the lateral interelectrode gap passes into an overheated metastable overheated state, allowing conductivity of the electrolyte to increase, and subsequently boils throughout its entire volume, reducing the likelihood of a low-voltage electrical breakdown.

EFFECT: ability to obtain high-quality small-diameter holes at a high piercing speed due to absence of a layer with a modified structure, burrs, and sharp edges with a finishing roughness of Ra 0.2-0.8 mcm.

1 cl, 5 dwg, 1 tbl, 1 ex