| 摘要 |
PROBLEM TO BE SOLVED: To provide a tool, giving chip handling property to a cutting edge and increasing the area of a chip discharge groove as compared with a linear cutting edge by shaping the drill tip cutting edge like a recessed part, and stabilizing the tool behavior in the process of cutting by providing a margin on the heel side to solve the problem. SOLUTION: In this drilling tool, the outer periphery of the tip part of the tool body rotated around an axis is provided with a pair of chip discharge grooves provided on the opposite sides with the axis interposed between them, and the cutting edge is provided at the tip of the wall surface facing the rotating direction of the chip discharge grooves. When the web thickness is W and the curvature of a substantially circular arc inscribing the cutting edge side groove bottom in the axial right-angled section is R1, a recessed cutting edge is formed with R1 ranging from 1.3 to 2.0, and another pair of margins are provided on the heel side to which a land part and a chip discharge groove are connected in the axial right-angled section of the drill tool. COPYRIGHT: (C)2006,JPO&NCIPI
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