| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a drill to be used for high-precision deep hole processing of a resin material.SOLUTION: In a drill 10 including a cutting part 12 on a tip end side and a shank part 30 on a rear end side, there is formed one streak of chip discharging groove 16 having a twisted half-moon shape. An entire outer peripheral surface of the cutting part 12 is regarded as a margin 14, and in the margin 14, minor grooves 20 are formed for supplying coolant to the cutting part 12 while being twisted in a reverse direction of the chip discharging groove 16 so as to circulate about a rotational axis of the drill 10. Moreover, the minor grooves 20 are divided by the chip discharge groove 16 and opened to the chip discharge groove. Further, at edge parts 22 formed at intersecting portions between lateral surfaces of the minor grooves 20 and the margin 14, setting treatment is not applied and thus cutting blades are not formed.</p> |
