| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To perform a test and sampling without pulling out rotary percussion drilling equipment from a drilled hole. <P>SOLUTION: When a bit body 21 abuts on a ground surface or the bottom of the drilled hole, a slide tip 20 attached by being housed in the drilling end of the bit body 21 closes a though-hole 12 formed in a penetrating state in the center-of-rotation portion of the bit body 21. Thus, drilling can be normally performed by attaching a drilling bit 1 to a leading end of a down-the-hole hammer 2. On the other hand, when the bit body 21 does not abut on the ground surface or the bottom of the drilled hole, the slide tip 20 slides obliquely downward in a radial direction by self-weight, so as to open the through-hole 12. Consequently, the bit body 21 is lifted together with the down-the-hole hammer 2, so that the test or the sampling of the bottom of the drilled hole can be performed through the through-hole 12 formed in the penetrating state in the center-of-rotation portion of the bit body 21. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
