| 摘要 |
PROBLEM TO BE SOLVED: To enhance excavating efficiency while suppressing manufacturing cost. SOLUTION: At a front end 34 of a rink bit 11, a plurality of crushing members 35 each having an upright portion 36 projecting forward and an inclined portion 37 formed from the top of the upright portion 36 along the periphery of the front end 34 in the direction opposite to a first direction are formed at predetermined angle intervals. By rotating the ring bit 11 in the forward rotation, the upright portions 36 of the crushing members 35 are brought into contact with the natural ground so as to crush the natural ground. In the conical portion 39 of the ring bit 11, projected streaks 40, 41 are formed toward the rear end of the conical portion 39 at predetermined angle intervals. Cutting powder generated by excavation and excavation water are properly guided by the projected streaks 40, 41, and moved backward. COPYRIGHT: (C)2011,JPO&INPIT
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