Throw-away tip for use in drilling work and throw-away drilling tool

Abstract

A throw-away tip for use in drilling work that has a convexly curved cutting edge portion at one end side of a cutting edge is provided. Chips are prevented from being sheared and packed, and cutting edge strength is secured to extend the service life of the tip. The tip is used with a drilling tool having a tool body rotatable about an axis and has a convexly curved surface formed on a rake face thereof on the one end side of the cutting edge, which forms a curve toward a seat face thereof as it proceeds toward the one end side of the cutting edge. The convexly curved cutting edge portion is formed at the side ridge of the convexly curved surface coinciding with the cutting edge and forms a substantially arc shape projecting in the direction of rotation of the tool when the tip body is viewed from the distal end side in the direction of the axis of the tool body, or when the tip body is viewed in a direction from closer to the other end of the cutting edge toward the inner periphery of the rear end of the tool. A throw-away tip is also provided which provides a stabilized cutting behavior and a reduced cutting force. A throw-away drilling tool is also provided that uses the above throw-away tip.