Drill body and manufacturing method of drill body
A drill body supplies a cutting fluid while securing stiffness of a leading end part. A body extends from a base end toward a leading end; a discharge groove to discharge chips; a fluid hole having a part which passes through an inside, of the body, of an inter-groove solid part of the discharge groove and causes a fluid to flow from the base end toward the leading end; and a mounting part in the leading end for mounting a cutting edge. The mounting part has a recessed part along the central axis of the body, and a cross section of the fluid hole changes from a circular shape to a non-circular shape midway along a path of the fluid hole from the base end toward the leading end, and assumes another non-circular shape in a portion which passes a side part of the recessed part.
1 . A drill body, comprising:
a body part which extends in a rod shape from a base end part toward a leading end part;
a discharge groove which is provided around a central axis of the body part in order to discharge chips;
a fluid hole which is provided such that at least a part thereof passes through an inside, of the body part, of an inter-groove solid part of the discharge groove and which causes a fluid to flow from a side of the base end part toward a side of the leading end part; and
a mounting part which is provided in the leading end part and which is for mounting a removable cutting edge member, wherein
the mounting part has a recessed part which is provided along the central axis of the body part from an end surface of the leading end part,
a hole cross section of the fluid hole orthogonal to a flow path direction thereof changes from a circular shape midway along a path of the fluid hole from the base end part toward the leading end part to a first non-circular shape which is longer in a circumferential direction than in a radial direction in an axial cross section of the body part closer to the leading end part, and is a second non-circular shape in a portion which passes a side of the recessed part, and
the first non-circular shape and second non-circular shape are the same as each other or are different from each other.
2 . The drill body according to claim 1 , wherein a cross sectional area of the hole cross section which has the first non-circular shape is equal to or smaller than a cross sectional area of the hole cross section which has the circular shape.
3 . The drill body according to claim 1 , wherein a discharge port in the leading end part of the fluid hole is provided directed toward a cutting edge of the cutting edge member mounted to the mounting part.
4 . The drill body according to claim 3 , wherein the discharge port is provided with the fluid hole being bent.
5 . The drill body according to claim 4 , wherein an opening portion of the discharge port, which discharges the fluid to a major cutting edge that forms the cutting edge, is a non-circular shape longer in a first direction along the major cutting edge than in a second direction that is perpendicular to the first direction.
6 . The drill body according to claim 1 , wherein the body part is formed of a steel material.