To provide a drill capable of compatibly decreasing manhours and securing the durability of a tool, and a drilling method.
This drill has two lines of chip discharging grooves extending in a straight line and parallel to a central line and a rake angle of a blade tip end 7 is formed at 0°. Consequently, a chip 15 cut off short in length in comparison with a conventional drill 1, the rake face 10 of which is inclined is formed and the produced chip 15 is certainly removed from a work by a coolant. Accordingly, it is possible to carry out drilling work at one-time feeding by abolishing step feeding and to decrease the manhours. Additionally, a ductility value increases in comparison with the cemented carbide made drill 1 as this drill is formed of high speed tool steel, and it is possible to prevent the breakage of a tip cutting edge 12. Furthermore, the durability of the tool is secured as the tip cutting edge 12 is honed.
TOYODA TOSHIO
ARAI KOJI
TAKEDA KATSUYOSHI
ISONO AKIRA
NISHIYAMA HIDEO
NAKAYAMA TAKESHI
OGAWARA HIROSHI
Miyazaki Yoshio
Kaoru Onozuka
Akio Tagami
High Masahiro
Toshio Nakamura