DOUBLE-DRILLING DEVICE AND DOUBLE-DRILLING METHOD

PROBLEM TO BE SOLVED: To simply and accurately machine a double-hole Dh. SOLUTION: This device is used for drilling the double hole Dh formed so that two parallel circular straight holes h1, h2 partially overlap each other in a workpiece. The device includes an outer tube 201, wherein an inner tube 300 is rotatably inserted in the outer tube 200, and a guide member 400 inserted in one previously formed circular straight hole h1 of the two circular straight holes is projected forward and fixed to the outer peripheral part of the front end of the outer tube 200. On the other hand, a drill head 100 is extended and fixed to the tip part of the inner tube 300 and the front end face of the drill head 100 is located in front of the front end of the outer tube 200 and in the midway of length of the guide member 400. COPYRIGHT: (C)2007,JPO&INPIT