公开(公告)号：US20200206828A1

公开(公告)日：2020-07-02

申请号：US16631305

申请日：2018-05-11

Applicant: NGK SPARK PLUG CO., LTD.

Inventor： Naoki ANDOH ,  Takuya HASEGAWA ,  Takashi FUJIMOTO

IPC: B23B27/16 ,  B23B27/22

Abstract: A cutting insert has cutting edges having the same shape and provided at respective corners of a polygon in rotational symmetry about the center axis of the polygon, is clamped in an upright position to a holder, and has a negative side rake angle on a rake face of a side cutting edge. A side cutting edge is present at an intersection ridge between a polygonal face and an outer peripheral face. The outer peripheral face includes a rake face of the cutting edge and a flank of an end cutting edge of another cutting edge different from the side cutting edge. The flank has a positive slope angle in opposition to a negative side rake angle of the side cutting edge. A breaker groove extending in a front-rear direction is formed in the rake face and cuts into the flank, in such a manner as to divide the rake face.