A boring bar for a non-rotating boring tool includes an elongated body configured for attachment to a support structure of a metal cutting machine and arranged to carry a tool part provided with a cutting element. At least two electrically controlled vibration actuators are arranged for active vibration damping of the boring bar. Each actuator includes a moveably arranged damping mass configured to generate vibratory forces in parallel with a working axis of the actuator that is perpendicular to a center axis of the damping mass. Each actuator is a single-axis actuator having one single working axis, wherein the actuators are arranged with their working axes angularly offset from each other. The actuators are arranged in a longitudinal series in the elongated body with the center axis of the damping mass of each actuator coinciding with a longitudinal axis of the elongated body.

A non-rotating boring tool for internal turning includes a boring bar having an elongated body, a cutting element with a rake side, a relief surface and a cutting edge, and an electrically controlled vibration actuator for active vibration damping of the boring bar. Moreover, when seen in a cross-sectional plane that is perpendicular to a longitudinal axis of the elongated body and intersecting the cutting edge in a radially outermost point, straight and imaginary first and second reference lines intersect the cutting edge in the radially outermost point with the first reference line extending at an angle of 6° to the relief surface on the outside of the cutting element, and the second reference line extending between the rake side and the relief surface at an angle of 10-40° to the first reference line. The actuator is arranged with its working axis extending in parallel with the second reference line.

A method for deburring an internally toothed workpiece includes providing a workpiece and a deburring tool. The workpiece has an inner toothing produced by hob peeling, with first and second tooth flanks. The deburring tool has a first cutting plate and a second cutting plate, diametrically opposed to the first cutting plate. The method includes rotating the workpiece in a first rotating direction and deburring the first tooth flanks with the first cutting plate while the deburring tool is not rotating. The method also includes shifting the deburring tool relative to the workpiece such that the first cutting plate and the second cutting plate do not contact the workpiece, rotating the workpiece in a second rotating direction, opposite the first rotating direction, further shifting the deburring tool relative to the workpiece, and deburring the second tooth flanks with the second cutting plate while the deburring tool is not rotating.

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.

An indexable cutting insert has a central mounting portion and two cutting portions. The central mounting portion has opposing upper and lower surfaces. The lower surface has two abutment elements associated therewith, each abutment element having two diverging abutment surfaces forming two abutment angles. The two cutting portions extend away from the central mounting portion, have distal cutting edges, and are entirely located in diagonally opposite imaginary quadrants of four quadrants defined by two mutually perpendicular quadrant planes. Two abutment bisector planes bisecting the two abutment angles and one of the quadrant planes are parallel or coincident. In a top view, the two cutting portions extend away from the central mounting portion in opposite directions. Two cutting bisector lines parallel to the two directions and bisecting the two cutting edges are mutually offset. A cutting tool has an insert holder and the cutting insert removably retained therein.

To provide a cutting insert such that a tool body can sufficiently hold the cutting insert even if one of cutting parts is broken. The cutting insert includes two side surfaces opposed to each other, a fixing hole passing through the centers of the two side surfaces, and an outer circumferential surface that is disposed between the outer circumferential edges of the two side surfaces and are connected to the outer circumferential edges of the two side surfaces. The outer circumferential surface includes four cutting parts, a first outer circumferential surface part that is disposed between the first cutting part and the second cutting part, and a second outer circumferential surface part that is opposed to the first outer circumferential surface part and is disposed between the third cutting part and the fourth cutting part. In a side view of the side surfaces from the axial direction of the fixing hole, the first outer circumferential surface part and the second outer circumferential surface part each have the center recessed toward the fixing hole, and a virtual arc having the same diameter as the diameter of the circumcircle of the cutting insert is in contact with two points on each of the outer circumferential surface parts.

Provided is a cutting insert having two cutting parts that is capable of entering a workpiece more deeply and easily supports machining of a groove or hole having a small diameter in a workpiece. A cutting insert includes: a body having at least an inner surface to be fixed to a tool body of a cutting tool and an outer surface opposed to the inner surface; and two cutting parts protruding in opposite directions in a longitudinal direction of the body. The cutting part includes: a cutting upper surface; a cutting front surface; and a first cutting side surface and a second cutting side surface. A front cutting edge is located on an edge between the cutting upper surface and the cutting front surface. In a projection view of the body as seen from the longitudinal direction, the cutting upper surfaces of the two cutting parts are oriented in directions opposed to each other, and front cutting edges of the two cutting parts are disposed so as to be more away from each other as being closer to the first cutting side surface from the second cutting side surface.

A turning toolholder includes a shank, a club head, and a clamp and a clamp screw for clamping a cutting insert. The club head includes a clamp coolant supply hole in fluid communication, a flank coolant supply hole and an auxiliary rake coolant supply hole, all in fluid communication with the main coolant supply hole. Coolant is supplied through a rake coolant exit opening formed in the forward nose portion of the clamp to direct coolant to the top rake surface of the cutting insert, and coolant is supplied through a flank coolant exit opening located below the insert-receiving pocket to provide coolant to the side flank surfaces of the cutting insert. In addition, an auxiliary rake coolant supply housing formed on a top surface of the club head supplies additional coolant to the top rake surface of the cutting insert during high heat applications.

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.

An insert may include a main body. The main body may include a first surface, a second surface, a side surface, a first cutting edge and a through hole. The side surface may be located between the first surface and the second surface. The first cutting edge may be located on at least a part of a ridge line where a first side surface of the side surface intersects with a second side surface adjacent to the first side surface. The through hole may open into the first surface. The main body may further include a first concave part located from the first surface to the side surface. The first concave part may be located away from an imaginary straight line connecting the first cutting edge and a center of the through hole in a front view of the first surface.