Examples of the cutting tool generally used for cutting metal materials and the like include those that a cutting insert having a cutting edge is mounted thereon. For example, Patent Document 1 describes a predetermined cutting insert, and a cutting tool with the cutting insert mounted thereon (specifically, an end mill).
FIG. 12(a) is a side view showing the related art cutting tool as described in Patent Document 1. FIG. 12(b) is an enlarged side view showing the related art cutting insert mounted on the cutting tool of FIG. 12(a). As shown in FIG. 12(a), a cutting tool 100 as being the end mill is constructed of a cutting insert 101 having a cutting edge, and a holder 111 having at the tip end thereof a cutting insert pocket 110 for mounting the cutting insert 101. The cutting using the cutting insert 101 is carried out by rotating the holder 111 around an axis 112 of the holder 111.
As shown in FIG. 12(b), the cutting insert 101 has a cutting edge at the ridge between an upper surface 102 and a side surface 103. The cutting edge is provided with a high-positioned corner cutting edge 104, and a low-positioned corner portion 106, which is lower in the thickness direction of the cutting insert 101 than the high-positioned corner cutting edge 104.
However, there is the problem that the cutting insert 101 thus constructed is subjected to large cutting force during cutting, and has low cutting performance. Patent Document 1: Japanese Unexamined Patent Publication No. 2004-148424