CUTTING TOOL

摘要

PROBLEM TO BE SOLVED: To improve the machining accuracy of a cutting tool by limiting a drop in its flexural rigidity and its chatter vibration. SOLUTION: A tool body 2 has a concave groove 14 cut in an external surface 3b of a head portion 3 between a peripheral cutting edge 10d and the back of the head portion 3. A shank portion 4 has an internal hollow blind hole 18 passing a center axis O. In the section taken just across the axis, the ratio Sa/Sb in the sectional area Sa of the blind hole 18 to the sectional area Sb of a thick-walled portion 19 of the shank portion 4 is set in the range of 0.2 to 1.3. This range ensures flexural rigidity and increases the natural frequency in cutting operations to thus diverge the natural frequency and the frequency of external force from a work from each other or suppress resonance.