Reamer

Abstract

A reamer incudes a core and a plurality of outer-circumference cutting edges provided on an outer circumference of the core and made of a hard tool material. The core extends from a front end to a rear end. The core is provided with a plurality of flutes from the front end to the rear end. A center-of-gravity adjustment portion, which adjusts a distance from a center of rotation to a center of gravity, is provided at least partially from terminal ends of the plurality of flutes on a rear end side to the rear end of the core. The center-of-gravity adjustment portion causes the deviation of the center of gravity from the center of rotation to be smaller than when no center-of-gravity adjustment portion is provided.

1 . A reamer comprising:
 a core; and   a plurality of outer-circumference cutting edges provided on an outer circumference of the core and made of a hard tool material,
 the core extending from a front end to a rear end, 
 the core being provided with a plurality of flutes extending from the front end to the rear end, 
 a center-of-gravity adjustment portion being provided at least partially from terminal ends of the plurality of flutes on a rear end side to the rear end of the core, 
 the center-of-gravity adjustment portion causing the distance from the center of rotation to the center of gravity to be smaller than when the center-of-gravity adjustment portion is not provided, 
   wherein the center-of-gravity adjustment portion is the terminal ends of the plurality of flutes, the terminal ends being provided at different positions in an axial direction.