COLLET FOR CUTTING TOOL HOLDER.

摘要

A metallic collet for a cutting tool holder having a structure wherein a cylinder portion (22) is formed in such a manner as to continue from a reduced diameter portion of a frustum (21) and only slits (20) are formed equidistantly in a circumferential direction in such a manner as to extend from an insertion port for a cutting tool (3) to the inside in the axial direction of the collet (2). In the collet of the present invention, a slit (20) reaches the cylinder portion (22) and the section (A) of that segment (S) of the cylinder portion (22) divided by slits is set to a maximum value so that the change of moment of inertia of area (It) with respect to axis X orthogonal to a collet radial direction and passing through the centroid of the sectional shape, with respect to the center angle THETA formed at the collet axis for the section, becomes substantially constant. Each slit (20) has the same width throughout its entire circumference and the number of the divided segments (S) can be set to within (number of division determined by the size (1)) +/- 2 or to 12. In this manner, each divided segment (S) is suitably flexible, clamping force and accuracy of the cutting tool (3) become sufficient and interference becomes great.