| 摘要 |
PROBLEM TO BE SOLVED: To maintain high sharpness of a cutting edge and effectively restrain generation of burr and edge chipping while preventing generation of abrasion, chipping or the like by ensuring cutting edge strength, especially in drilling a through-hole in a workpiece made of cast iron or the like. SOLUTION: The cutting edge 5 is formed at an intersection ridge line portion between a wall surface directed in a drill rotational direction T of a cutting chip discharge groove 4 formed on an outer periphery of a tip of a drill body 1 rotating around an axial line O and a tip flank 3. The drill body 1 is formed of cemented carbide. The cutting edge 5 is provided with: a main cutting edge portion 8 on the inner periphery side of the drill body 1; and a deburring cutting edge portion 12 on the outer periphery side, the tip angle θ of which is smaller, and the length L of which is shorter than those of the main cutting edge portion 8. Besides, the main cutting edge portion 8 is subjected to honing, and the deburring cutting edge portion 12 is not subjected to honing or subjected to honing having a honing width smaller than that of the main cutting edge portion 12. COPYRIGHT: (C)2010,JPO&INPIT |
