| 摘要 |
PROBLEM TO BE SOLVED: To provide a drilling tool suitably used in a wide range from a ground formed of soft nature soil including a ground layer containing a cobbled stone or the like to a ground formed of relatively hard nature soil for drilling the ground in any direction such as the sloping direction or the vertical direction. SOLUTION: An open recessed portion 24 is formed at the outer periphery at the front end of a device 20 rotated around a center axis O. A diameter enlarged bit 30 is mounted at the front end of the device 20 rotatably around a rotating axis P eccentric from the center axis O so that it is protruded outward when the device 20 is rotated in one direction and set in the recessed portion 24 when it is rotated in the other direction. Carbide chips K are provided at the front end of the device 20 and on the diameter enlarged bit 30 to form drill parts D at the front end of the device 20 and on the diameter enlarged bit 30. COPYRIGHT: (C)2006,JPO&NCIPI
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