To make it possible for bores (16) that are in line with one another to be efficiently worked by means of a boring bar (2), the boring bar has a main body (10) with an axis of rotation (R) and a number of cutting elements (12, 12A) at intervals from one another in the axial direction (4) and also guiding elements (14) for guiding the main body (10) in a guiding bore (16A). The guiding elements (14) are kept at a distance from the axis of rotation (R) equivalent to a guide radius (r1). The main body (10) is divided into a functional region (19) and an eccentric region (10), wherein the cutting elements (12, 12A) and the guiding elements (14) are arranged such that they are distributed around the main body (10) over an angular range (a) of less than 180°. Furthermore, the circumferential side (22) of the main body (10) can be passed eccentrically through a respective bore (16, 16A) of which the unworked tube radius (r2) is less than the guide radius (r1).

A high-speed tool holder includes: a tool shaft for accommodating a tool at its first end, and a machine clamping part which is integrally connected to the tool shaft and forms an interface for clamping in the machine; with the tool shaft being substantially truncated circular cone-shaped, a first diameter at the first end with the tool insertion opening being smaller than a fifth diameter at the second end at the machine clamping part; and a portion of the substantially truncated circular cone-shaped tool shaft having an outwardly bulging, preferably spherical, shape between the tool insertion opening and the machine clamping part.

A tool head having a main body (2) that is rotatable about a tool head axis (5), a slide (6) for holding a cutting tool, the slide (6) being guided on the main body (2) in a slide guide (8) in a linearly moveable manner transversely to the tool head axis (5), and a clamping device (48) for clamping the slide (6) on the main body (2). The clamping device (48) has a clamping body (50) that is adjustable parallel to the tool head axis (5), the clamping body (50), in a clamping position, pressing a sliding face (46) of the slide (6) against a guiding surface (44) of the slide guide (8) with a clamping force (F.sub.N) being introduced.

A tool holder is provided comprising a base body for coupling with a drive spindle that can be driven rotatingly, whereon a clamping chuck for clamping a tool is provided, further comprising a damping element arranged between the base body and the clamping chuck, wherein the damping element is made of an elastomeric material or of a shape memory alloy, and wherein the clamping chuck is solely connected to the base body by means of the damping element.

A collet assembly of improved stability has a collet, an axial limiting assembly, a cutter, a pin, and multiple damping elements. The collet has a containing space, a pin-receiving groove, a connecting groove, and multiple receiving grooves. The containing space is formed through the collet. The pin-receiving groove is formed through the collet. The connecting groove is recessed on the collet. The multiple receiving grooves are recessed in the collet. The axial limiting assembly is mounted to the collet. The cutter has a limiting groove and a mounting end. The limiting groove is recessed on the cutter. The mounting end abuts against the limiting assembly. The pin extends into the pin-receiving groove and abuts against the limiting groove of the cutter. Each one of the multiple damping elements is received in a respective one of the multiple receiving grooves of the collet. A collet of improved stability is also provided.

A collet assembly of improved stability has a collet, an axial limiting assembly, a cutter, a pin, and multiple damping elements. The collet has a containing space, a pin-receiving groove, a connecting groove, and multiple receiving grooves. The containing space is formed through the collet. The pin-receiving groove is formed through the collet. The connecting groove is recessed on the collet. The multiple receiving grooves are recessed in the collet. The axial limiting assembly is mounted to the collet. The cutter has a limiting groove and a mounting end. The limiting groove is recessed on the cutter. The mounting end abuts against the limiting assembly. The pin extends into the pin-receiving groove and abuts against the limiting groove of the cutter. Each one of the multiple damping elements is received in a respective one of the multiple receiving grooves of the collet. A collet of improved stability is also provided.

A resonant frequency dampened through-coolant machine tool for selective mounting to machining systems for precision vibration free machining and has an elongate tool body. An internal dampening chamber is defined within the machine tool body and contains a resonant frequency dampening mass that is moveable within the dampening chamber. Axial and diametrical tunable dampening devices support the dampening mass in spaced relation with internal walls of the dampening chamber. A tuning piston is moveable within the machine tool body and has a tuning flange that is disposed in contact with one of the axial tunable dampening devices. The tuning piston has a pair of oppositely angulated surfaces that are selectively engaged by angulated drive heads of adjustment screws that are supported by threaded openings of the tool body and are rotated to selectively drive the tuning piston forwardly or rearwardly for precise tuning activity. Internal components of the machine tool define a coolant fluid flow passage to conduct a jet of coolant fluid to the metal cutting interface.

A high-speed tool holder includes: a tool shaft for accommodating a tool at its first end, and a machine clamping part which is integrally connected to the tool shaft and forms an interface for clamping in the machine; with the tool shaft being substantially truncated circular cone-shaped, a first diameter at the first end with the tool insertion opening being smaller than a fifth diameter at the second end at the machine clamping part; and a portion of the substantially truncated circular cone-shaped tool shaft having an outwardly bulging, preferably spherical, shape between the tool insertion opening and the machine clamping part.

A tool holder is provided comprising a base body for coupling with a drive spindle that can be driven rotatingly, whereon a clamping chuck for clamping a tool is provided, further comprising a damping element arranged between the base body and the clamping chuck, wherein the damping element is made of an elastomeric material or of a shape memory alloy, and wherein the clamping chuck is solely connected to the base body by means of the damping element.

A tunable or tuned boring bar having increased stiffness is provided. Increasing the stiffness of the bar increases the natural frequency, thereby reducing directional deformation of the bar during use. The tunable boring bar includes a distal portion configured to support a tool, a proximal portion configured for attachment to a support structure of a metalworking machine, and a body, which is at least partially tubular, extending between the proximal portion and the distal portion. The tubular portion of the body has an elongated cylindrical cavity. The body of the boring bar includes a core layer formed from a first material and a coating layer formed from a second material. The second material has a higher modulus of elasticity than the first material. In certain configurations, the coating layer is bonded to the core layer by cladding, welding, chemical adhesives, chemical vapor deposition, pulsated plasma diffusion, or combinations thereof.