Opening maching apparatus for heat transfer tube, method of forming opening in tube wall of heat transfer tube using same, and method of removing foreign material through same opening of same heat transfer tube

A method of machining an opening in a tube wall of a heat transfer tube, the method comprising:

• inserting an electric discharge machining device connected to an electric discharge machining transport device to form an opening in the tube wall of the heat transfer tube;
• moving the electric discharge machining device inserted into the heat transfer tube to a target site in which the opening is to be formed by using the electric discharge machining transport device;
• rotating the electric discharge machining device moved to the target site using an electric discharge machining device rotation device and bringing the electric discharge machining device into contact with the tube wall of the heat transfer tube using an electric discharge machining device driving device;
• and
• forming an opening in the tube wall of the heat transfer tube by using the electric discharge machining device in contact with the tube wall of the heat transfer tube,
• wherein the electric discharge machining device comprises:
• a housing having a through hole extending in a radial direction, inserted into the heat transfer tube, and extending in a longitudinal direction of the heat transfer tube;
• a discharge body disposed in the housing, movably disposed through the through hole, and provided with a discharge electrode on a first surface facing the tube wall surface of the heat transfer tube;
• an operating shaft disposed in the housing, moved in a longitudinal direction of the housing by the electric discharge machining device driving device, and configured to move the discharge body to the outside through the through hole;
• and
• a dielectric supply member disposed in the housing and configured to supply a dielectric to the discharge electrode of the discharge body.