A boring bar with electrodynamic actuators is for counteracting vibrations and machine tool provided with such a bar. The boring bar includes a wall, an internal recess and a longitudinal axis. The boring bar has a first electrodynamic actuator with coil windings associated with a moving mass and a spring assembly that are arranged to define a first actuation direction perpendicular to the longitudinal axis of the boring bar. A second electrodynamic actuator has coil windings associated with a moving mass and a spring assembly that are arranged to define a second actuation direction perpendicular to both the first actuation direction and the longitudinal axis of the boring bar. The actuators allow counteraction of the vibrations in the directions perpendicular to the longitudinal axis of the bar. The longitudinal axis also defines the boring direction.

A holder according to one embodiment has a rod shape and includes a head portion located at a front end side. The head portion includes an upper jaw portion and a lower jaw portion located at a front end, an insert pocket located between the upper jaw portion and the lower jaw portion, a first wall surface located at an upper surface of the upper jaw portion and inclined in an extending manner from one side surface side, a second wall surface located closer to a rear end side than the first wall surface and inclined upward, a concave-shaped third wall surface located closer to the rear end side than the second wall surface, and a fourth wall surface inclined upward as the fourth wall surface extends away from the third wall surface. The third wall surface is concave downward from an upper end of the second wall surface.

A holder according to one embodiment has a rod shape and includes a head portion located at a front end side. The head portion includes an upper jaw portion and a lower jaw portion located at a front end, an insert pocket located between the upper jaw portion and the lower jaw portion, a first wall surface located at an upper surface of the upper jaw portion and inclined in an extending manner from one side surface side, a second wall surface located closer to a rear end side than the first wall surface and inclined upward, a concave-shaped third wall surface located closer to the rear end side than the second wall surface, and a fourth wall surface inclined upward as the fourth wall surface extends away from the third wall surface. The third wall surface is concave downward from an upper end of the second wall surface.

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).

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 holder in a non-limiting aspect of the present disclosure may include a base having a bar shape extended from a first end to a second end along a central axis, and a first weight having a column shape and a second weight having a column shape. The base may include a cavity extended along a central axis. The first weight may be located in the cavity. The second weight may be located in the cavity and located closer to the second end than the first weight.

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 formed rotary cutting tool includes a cutting edge defining a cutting edge diameter that is increased and reduced in a direction of an axis of the tool, so as to have at least one neck portion in which the cutting edge diameter is minimized. The cutting tool includes a roughing portion which is provided on a periphery thereof and which is constituted by a succession of protrusions and recesses arranged in the direction of the axis. The roughing portion includes (i) a fine roughing portion that is provided in at least one of the at least one neck portion, and (ii) another portion that is provided in a portion that is other than the at least one of the at least one neck portion. The fine roughing portion of the roughing portion is different in characteristics from the above-described another portion of the roughing portion.

A holder for a cutting tool for processing of workpieces has a first part for holding a cutting tool (150), a second part (120) to which the first part is fastened, and a fastening element (140). An adjustment element adjusts the position of the first part in relation to the second part. The first and second parts have a first bore and a second bore for receiving the fastening element and a recess (118, 128) for receiving the adjustment element. The first part has an abutment surface (115) placed onto a contact surface (122) of the second part, such that the central axes (A-A) for the first and second bores become parallel. The abutment surface of the first part and the contact surface of the second part are inclined in relation to the feeding axis (G-G) of the work piece towards the cutting tool (150).

A blade portion for a grooving tool includes opposite first and second surfaces, a blade width thereof being defined as a shortest distance between the first and second surfaces, opposite third and fourth surfaces, and a fifth surface and an opposite blade portion end. The blade width is constant or substantially constant from the fifth surface up to the blade portion end. An insert seat separating the third surface and the fifth surface is arranged to receive an insert having a main cutting edge, an associated rake face, and an associated main clearance surface. The main cutting edge defines an insert width being greater than the blade width. A shortest distance from the fifth surface to the opposite blade portion end is greater than a shortest distance from the third surface to the fourth surface.