ELECTRIC DISCHARGE MACHINING APPARATUS AND METHOD

摘要

An electron discharge machining apparatus and method is provided for precisely machining a wall of a tubular member to form a wall portion thereof defined by a slot of predetermined configuration at a predetermined location in a wall of the tubular member. The tubular member may be a nuclear steam generator tube. The apparatus includes a housing sized to be disposed in the tube, the housing having an opening therethrough capable of being aligned with the predetermined location in the tube wall to be electro-machined. An electrode is housed in the housing for generating an electron discharge arc between the electrode and the wall of the tube in order to machine the slot at the predetermined location. A rotator is connected to the housing for precisely rotating the housing, so that the opening formed through the housing is rotated into registry with the predetermined location to be electro-machined. An extender mechanism housed in the housing is connected to the electrode for precisely extending the electrode through the opening of the housing as the electrode machines the tube wall. As the electrode forms the slot in the wall of the tube, the extender mechanism, which includes a worm gear, gear wheel and threaded axle combination connected to the electrode, precisely advances the electrode to precisely electro-machine the slot in the wall of the tube.