| 摘要 |
PURPOSE:To increase drilling speed of a drill, by notching the point end part of the drill for a pipe cleaner. CONSTITUTION:Striaght shaped cutting edges (a) are formed in the peripheral part of a drill main body 1 welded to a shank 3, and grooves 2 are formed in the point end so as to obtain an angle theta of 60 deg.-70 deg., then sharpened ends 6 are formed by intersecting points of the cutting edges (a) and the grooves 2. Pressure water is fed to a through hole 4 communicated to jetting ports 5, and the water is injected from the jetting ports 5 when scale in a machine pipe is cut and removed. The cutting edge (a) may be spirally shaped. |
