THROW-AWAY TYPE DRILLING TOOL

摘要

PROBLEM TO BE SOLVED: To prevent deterioration of machining precision without swinging of a tool main body at the time of chamfering of a cutting edge even in the case of applying drilling work on a groove a cross section of which makes a recessed curve or a bottom surface of a recessed part on a drilling tool on a tool head end outer peripheral side and an inner peripheral side of which cutting edge tips are arranged biased. SOLUTION: A first outer peripheral side cutting edge tip 13 furnished with a cutting edge 19 on one side with an axis○inbetween of which an outer peripheral end is projected to an outer periphery of a tool main body 1 is installed on a head end of the tool main body 1 to be rotated around the axis○free to connect and disconnect to and from it. Additionally, on the other side with the axis○inbetween, an inner peripheral side cutting edge tip 14 furnished with the cutting edge 19 an inner peripheral end of which reaches the axis○and a second outer peripheral side cutting edge tip 15 furnished with the cutting edge 19 an outer peripheral end of which is projected to the outer periphery of the tool main body 1 are installed free to connect and disconnect to and from it.