| 摘要 |
PROBLEM TO BE SOLVED: To provide a drill tool capable of cutting the inner peripheral surface of a hole to easily form a deep recessed part. SOLUTION: The drill tool 10 used is characterized in that an annular guide plate 35 freely revolvable with respect to a long rod-shaped shank 20 is mounted on the outer periphery on the midway part of the shank 20 and a head 11, of which the diameter is larger than that of the shank 20 is provided to the leading end of the shank 20, that one or a plurality of ribs 15a, 15b and 15c formed along the peripheral direction of the head 11 are provided to the side surface of the head 11 in a protruded state, and that cutting blades 16a, 16b and 16c are arranged to protruded end edges of the ribs 15a, 15b and 15c in a protruded state. COPYRIGHT: (C)2006,JPO&NCIPI
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