| 摘要 |
At a portion of a through hole (16) in a plate-shaped insert (11), a tapered portion (17) having its diameter enlarged toward one half (3) is provided. A conical spring (12) is inserted to a hole provided in the one half (3), and fitted at an underhead neck of a clamp screw (4) seated in a bore (6). A tapered ring (13) fitted in the through hole (16) and having an inclined surface (13a) of such a shape that corresponds to the tapered portion (17) of through hole (16) is provided below the conical spring (12). By the recovering forces of the conical spring (12) and the other half (7), the tapered ring (13) presses the plate-shaped insert (11) toward the bottom surface (9) of a slot (2), and further, friction force between threads of the male screw portion of clamp screw (4) and threads of a female screw portion provided in the other half (7) is maintained. As a result, a ball nose end mill is provided in which loosening of the clamp screw caused by run out resulting from variation in cutting force is prevented. <IMAGE> |
