Patent attributes
Chips are segmented to have a desired width and the chip controllability is improved and the tool rigidity is improved. A drilling tool is provided that includes: a tool body; a chip discharge groove formed at the outer periphery of the tool body; at least one sub-groove formed at an inner face facing the front side in the tool rotation direction T of the chip discharge groove; a rake face; a tip end flank face; and a cutting edge formed at a ridge line at which the tip end flank face intersects with the rake face. The plurality of rake faces form a step-like shape having at least one step section. The drilling tool is configured so that the turnup section of the sub-groove is turned up in a different direction from the direction along which the turnup section of the chip discharge groove is turned up.
