| 摘要 |
A cutting head having a tapered shaft portion, a helical flute, and a flat shoulder surface is fastened to a shank having a front end surface, a tapered hole, and a helical flute through a fastening attachment in the form of a helical coil. The fastening attachment has a sectional shape substantially analogous in shape to a space defined between the helical flutes. The fastening attachment is fitted in one of the helical flutes, and is threaded into the other of the helical flutes until the shoulder surface is brought into close contact with the front end surface of the shank, and the outer peripheral surface of the tapered shaft portion is brought into close contact with the inner surface of the tapered hole, thus fastening the cutting head to the shank. |
