| 摘要 |
PROBLEM TO BE SOLVED: To provide a drill bit holding device to generate fine vibration in a drill bit using a force to press the cutting tip of the drill bit to an object to be drilled, whereby it is possible to heighten the machining efficiency in drilling a concrete object in which drilling is performed while the surface to be machined is crushed by the cutting tip of the drill bit, to reduce the labor and burden of the operator, and lessen the noise and vibration as consideration for the environment. SOLUTION: The drill bit holding device is composed of a shank body 1 having a shank 1a located over, a sliding member 3 engaged with the shank body, rotating in a single piece, and admitting attachment of a drill chuck A to its bottom, and a ball 12 installed between the shank body 1 and the sliding member 3, pinched by tapered surfaces 9 and 11, revolving while it rotates round its own axis in such a condition as abutting to an outer sleeve 15, and generating fine vibrations in the axial direction relative to the sliding member 3 while it intrudes to and comes out of a ball dropping recess 10 provided at the tapered surface 9.
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