THROWAWAY TYPE DRILL

摘要

PROBLEM TO BE SOLVED: To surely supply a sufficient amount of cutting oil to a central part of a cutting blade 7 at an edge of a throwaway tip 8. SOLUTION: A concave-groove-shaped tip mounting seat 6 opening to a tip end surface 3 of a drill body 1 is formed at a tip end part of the nearly cylindrical drill body 1 rotated on an axis line O. The tabular throwaway tip 8 having the cutting blade 7 formed on its tip end is detachably mounted on the tip mounting seat 6. A oil hole 5 supplying the cutting oil is formed on a tip end side of the drill body 1, and also on the tip end side of the drill body 1, an oil groove 11 communicating with the oil hole 5 is formed so as to open to the tip end surface 3 along a groove wall surface 6b of the concave-groove- shaped tip mounting seat 6. The cutting oil is discharged through a clearance partitioned between the oil groove 11 and a side surface 15 of the throwaway tip 8 opposite to the groove wall surface 6b.