| 摘要 |
<p>A drill capable of suppressing inter-layer peeling (delamination) while keeping hole diameter accuracy even if the number of holed to be worked increases is provided. The drill includes a first flank which has a ridge line forming a cutting edge, a second flank which is adjacent to the first flank and has a ridge line forming a land portion, and a third flank which is adjacent to the first flank and has a ridge line forming a chisel edge. The drill further includes a fourth flank which is surrounded by a ridge line forming the first flank, a ridge line forming the third flank, and a trough line forming the second flank.</p> |
