| 摘要 |
PROBLEM TO BE SOLVED: To provide a drilling tool capable of further improving hole position accuracy and breakage resistance.SOLUTION: In a drilling tool, two cutting edges 2 are provided at a tip of a tool body 1, two spiral chip discharge grooves 3a, 3b are formed to be connected in the midway section on an outer periphery of the tool body 1, and each chip discharge groove 3a, 3b is provided in parallel from a connecting section. The total of a peripheral direction length of a margin 4 is 20% or more and 55% or less of a circumferential length of a circle of a tool diameter in a range not more than 1 times of the tool diameter in an axial direction from a tool tip. Thickness of a hard film 5 provided on a tool outer peripheral surface is 0.5 μm or more and 10 μm or less in a range not more than 1 times of the tool diameter in the axial direction from the tool tip. The hard film 5 is provided to be thicker toward the tool tip side. Web thickness W of the tool is 20% or more and 60% or less of the tool diameter.SELECTED DRAWING: Figure 2 |
