| 摘要 |
<p>A hammer bit includes a bit body coupled to a hammer drill, a housing bit disposed to the bit body, at least one wing bit coupled to the housing bit to move up and down slantly, and having a rotating radius that is more increased than an outer surface of the bit body when moving up and is more decreased than the outer surface of the bit body when moving down, and at least one spacer installed to move up and down together with the wing bit and filling up an upper space of the wing bit when the wing bit moves down.</p> |
