To provide a drill bit hardly causing damage thereon such as chipping or cracking even if it is used for high speed drilling of hard rock and a manufacturing method thereof.
A drill bit 1 made of steel material for rock drilling comprises: a cylindrical part 2 which has an annular rear end surface 3 and a bottomed hole 4 opened at the center part of the rear end surface 3 and extending in the axial direction thereof and the whole of which is cylindrically formed; and a tip part 6 which is continuous with the front end side of the cylindrical part 2 and has a diameter enlarged toward a front end surface 8. In the drill bit 1, a plurality of fiber flows FL penetrating in parallel with each other and continuously along the axial direction of the cylindrical part 2 and the tip part 6.
NAKAO SATOSHI
TSURUTA YASUHIKO
YOSHIDA TAKAHIKO
MITSUBISHI MATERIALS CORP