Patent ID: 7883302

Claim:
A cutting tool holder unit that is adapted to be detachably mounted on a rotational axis of a head of a machine tool, the cutting tool holder unit, comprising: a cutting tool holder; a front cover provided in front of the head and formed with an opening that slidingly contacts an outer periphery of a flange section of the cutting tool holder, wherein a cutting oil circulating channel is formed between an inner periphery of the opening and the outer periphery of the flange section of the cutting tool holder, and a cutting oil supply route comprising a horizontal hole with an inner end and an outer end, wherein the outer end serves as a cutting oil admission port opening into the cutting oil circulating channel, and a vertical hole with an upper end and a lower end, wherein the inner end of the horizontal hole is connected to the lower end of the vertical hole, and wherein the upper end of the vertical hole serves as a cutting oil injection port opening into a position eccentric from an axis of the cutting tool holder on an upstream side of a cutting tool in a direction of rotation of the cutting tool holder, and an angle of a rear surface of the horizontal hole relative to a tangent line based on the direction of rotation of the cutting tool holder set larger than 90 degrees.