| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a surface coated drill having a hard coating layer exhibiting excellent wear resistance and high finishing surface accuracy even in a high speed broaching condition. <P>SOLUTION: In this surface coated broach, the hard coating layer exists directly on a broach base body or through an intermediate layer, has a layer thickness of 0.2 to 5μm, and is formed of a component system of (Cr<SB POS="POST">1-X</SB>Al<SB POS="POST">X</SB>)N äx=0.2 to 0.6} as a grain diameter control layer on the outer most surface. A hard coating film is composed so that, when a crystal grain shape in a film cross section of a cutting blade configuring the broach is observed, the crystal grain is constituted of a columnar crystal having a width of 15 to 120 nm and a height of 0.2 to 5μm, and from a tip end toward the rear end of the cutting blade of the broach, a region in which an average aspect ratio of the crystal grain configuring the grain diameter control layer is gradually reduced to one third of the average aspect ratio of the crystal grain at the tip end of the cutting blade within a range of 1 to 100 exists over a length of equal to or more than one half of a tool cutting blade part in the length direction of the broach. <P>COPYRIGHT: (C)2012,JPO&INPIT</p> |
