| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To remove a burr generated when working a through-hole, by continuing with boring work. <P>SOLUTION: In a four-blade drill, the drill is composed of a pair of first cutting edges 1 for precedently performing the boring work in a diameter smaller than a drill diameter for primary cutting, and a pair of second cutting edges 2 for removing the burr generated in the boring work and the primary cutting of an uncut part of the first cutting edges in a drill diameter for secondary cutting. The burr removing drill is characterized by setting a diametral difference between the first cutting edges and the second cutting edges to 1.0 % to 10.0 % in the drill diameter ratio of the second cutting edges. <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
