| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a surface coated drill whose hard coating layer exhibits excellent wear resistance and chip discharging characteristics even in the conditions of high-feed dry deep-hole drilling work. <P>SOLUTION: When observing a crystalline grain shape of a film section of a flank face of a drill fore end, a crystal grain composing a grain size control layer consists of a columnar crystal of a width of 10-100 nm, and a height of 0.2-6.0 μm, and when observing a crystal grain shape of the film section of a cutting blade composing the grain size control layer in a region from the drill fore-end to a position distant from the drill fore-end by the length of 5 times the drill diameter along the length of a drill base body out of a chip discharging groove of the drill, an average aspect ratio of the crystal grain composing the grain size control layer is gradually reduced in a range of 1-100 backward from the drill fore-end, and an average aspect ratio at a position distant from the drill fore-end by the length of 0.01 times the diameter is ≥2 times the average aspect ratio at the position of 5 times the diameter. <P>COPYRIGHT: (C)2012,JPO&INPIT |
