A cutting insert includes a cylindrical body portion, a cutting portion, a first fitting portion, a second fitting portion, and a third fitting portion. The cutting portion includes a rake face and a flank face. A ridgeline between the rake face and the flank face constitutes a cutting edge. When viewed in the axial direction, the cutting portion is provided opposite to the third fitting portion relative to the insertion hole. When viewed in the axial direction, a straight line extending through an outer circumferential end of the cutting edge and a center of the insertion hole overlaps with the third fitting portion and is located between the first fitting portion and the second fitting portion. A third central angle is smaller than a first central angle and is smaller than a second central angle.

A tool retainer is provided. The tool has a retainer sleeve having a longitudinal external tab to engage with an internal recessed radial groove with a tool holder, and wherein the retainer sleeve has two internal radial tabs that engage with a recessed groove in a rotating tool shank. A cutting tool assembly including a cutting bit and the retainer sleeve is provided.

A cutting tool includes a shaft portion. The shaft portion includes an increased-diameter portion having a diameter larger than a diameter of other portion of the shaft portion. The increased-diameter portion has a recessed portion formed in a peripheral surface of the increased-diameter portion.

Provided is a tool holding structure capable of effectively preventing a cutting tool from coming off a chuck portion. An outer fitting portion A is formed in an outer face of a shank portion 2 of a cutting tool T and an inner fitting portion B is formed in an inner face of a chuck portion 12 of a tool holder. A fitting member 20 is provided to be fitted to the outer fitting portion A and the inner fitting portion B respectively. The fitting member 20 includes a protruding portion 22 which protrudes from an outer circumference of the shank portion 2 when fitted to the outer fitting portion A. A guide groove 18 is formed for guiding the protruding portion 22 of the fitting member 20 from an open side of an inner space 13 to the inner fitting portion B. The inner fitting portion B includes a rotation preventing face for preventing relative rotation between a holder body 10 and the cutting tool T in association with contact thereof with the protruding portion 22 and a slip-out preventing face for preventing slip-out of the cutting tool T in association with contact thereof with the protruding portion 22.

A tool retainer is provided. The tool has a retainer sleeve having a longitudinal external tab to engage with an internal recessed radial groove with a tool holder, and wherein the retainer sleeve has two internal radial tabs that engage with a recessed groove in a rotating tool shank. A cutting tool assembly including a cutting bit and the retainer sleeve is provided.

A clamping device for clamping a workpiece to a machine spindle includes at least one clamping bush which extends around a central axis and has at least one clamping surface for the workpiece and at least one clamping body. The clamping bush on a side remote from the clamping surface at least one support surface which extends about the central axis along a helical line. On a side facing, the clamping bush comprises at least one support surface which extends about the central axis along a helical line with a predefined pitch and is inclined at an angle of inclination to a direction axial to the central axis. The clamping body includes a hydraulic chamber in the interior of the clamping body. The clamping device also includes a displacement element, and at least one pressure generator. A clamping force is generatable between the clamping bush and workpiece.

The disclosure relates to a tool holder having a tool portion and a tool interface portion, wherein the tool interface portion has a lateral surface area which is of rotationally symmetrical design and extends over a predetermined axial length and wherein the tool interface portion has sections with non-round cross section.

A cutting insert includes a cylindrical body portion, a cutting portion, a first fitting portion, a second fitting portion, and a third fitting portion. The cutting portion includes a rake face and a flank face. A ridgeline between the rake face and the flank face constitutes a cutting edge. When viewed in the axial direction, the cutting portion is provided opposite to the third fitting portion relative to the insertion hole. When viewed in the axial direction, a straight line extending through an outer circumferential end of the cutting edge and a center of the insertion hole overlaps with the third fitting portion and is located between the first fitting portion and the second fitting portion. A third central angle is smaller than a first central angle and is smaller than a second central angle.

A tapered countersink drill bit includes at least two screwing knifes and at least one two screwing trenches and a rod body; a length of an edge of the left lateral side of each screwing knife being shorten than that of an edge of the right lateral side thereof; each screwing knife including a front drilling head; a tapered portion formed at a backside of the front drilling head; a rear drilling head formed at a backside of the tapered portion; the screwing angle of each screwing knife being identical from the front drilling head to the rear drilling head; and a screwing angle of each screwing trench being identical from the front drilling head to the rear drilling head; a width between two adjacent knifes at a front end of the rear drilling head being longer than a width between two knifes at rear ends of two rear drilling head.

A rotating tool includes a circumferential surface formed with a tool anchorage arrangement. The tool anchorage arrangement follows a stepped path. The tool anchorage arrangement includes an entry recess and, subsequent thereto, a radial recess and, subsequent thereto, an axial recess. Additional radial and axial recesses may be alternated to increase the number of steps, thereby extending the length of the stepped path.