| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a drilling bit that ensures performance of discharging slime (drill powder) while ensuring an increased length of a guide surface in a circumferential direction to improve straight advance performance. <P>SOLUTION: A drilling bit A is provided, in which a metal base 1 has a coupling surface 11 to which a tip of a rock drill, a rock bolt or the like is coupled; a blade body holding surface 12 on which a plurality of blade bodies 2a to 2c are arranged; and an outer peripheral side surface 13 formed of guide surfaces 13a1 to 13a3 for maintaining straight advance performance between the coupling surface 11 and the blade body holding surface 12 during drilling, and of discharge groove surfaces 13b1 to 13b3 recessed more than the guide surfaces 13a1 to 13a3, respectively, for discharging slime produced during drilling. On the blade body holding surface 12, the plurality of blade bodies 2a to 2c are arranged such that a circumferential length of the drilling bit A in a rotating directionαon each of the guide surfaces 13a1 to 13a3 is longer than the circumferential length of the drilling bit A in a counter-rotating directionβon each of the guide surfaces 13a1 to 13a3, on the basis of a position on which each of the blade bodies 2a to 2c is arranged. <P>COPYRIGHT: (C)2013,JPO&INPIT</p> |
