| 摘要 |
<p>A core cutter (C) of high drilling performance capable of discharging chips smoothly comprises a tubular body section (1), and a plurality of cutting edges (2) arranged at the tip thereof at a predetermined interval in the circumferential direction wherein at least one of the plurality of cutting edges (2) functions as an inner cutting edge (2A) and the remainder function as outer cutting edges (2A). The body section (1) is made thin but can sustain deformation resistant performance, and a through groove (3) penetrating in the thickness direction is provided to open on the tip side. The cutting edge (2) consisting of a chip independent from the body section (1) and having a dimension equal to the circumferential dimension of the through groove (3) is inserted into the through groove (3) and fixed in place. A garret (4) for discharging chips is formed in front of the cutting edge (2) in the rotational direction by the outer circumferential surface which approaches the inner circumferential surface toward the tip side. The cutting edge (2) is inserted into the through groove (3) and fixed by welding under such a state as the inside diameter end at the tip of the cutting edge (2) in the axial direction is aligned or substantially aligned with the circumferential surface at the tip of the garret (4) in the axial direction.</p> |
