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.

The present invention provides a cutting tool which comprises a cutting tool insert with a tip portion of cBN material having a cutting edge formed therein and a base portion forming a sintered composition with the tip portion, and a body portion coupling the cutting tool insert with a shank of the cutting tool, wherein the cutting tool insert has a rake face and a first flank face defining the cutting edge. The rake face has a negative rake angle relative to an axis parallel to a center axis of the body portion. A second flank face defining a further edge with the first flank face is formed such that the cutting edge and the further edge do not have a common vertex. The second flank face is tilted with respect to an axis parallel to a center axis of the body portion by an angle greater than 0.

A cutting tool with sufficient stiffness of a body is provided.

A cutting tool 10 includes a body 100 in which a discharge groove 120 for guiding and discharging chips is formed, and a cutting insert 200 fastened and fixed on a distal end side of the body 100. The cutting insert 200 includes a first surface 210 through which a through-hole 230 is opened, and a major cutting edge 231 formed so as to extend straight at an end part of the first surface 210. A protrusion portion 130 protruding so as to cover part of the first surface 210 of the cutting insert 200 from outside is formed at the body 100. A clearance hole 170 is formed so as to extend from a surface of the body 100 opposite the cutting insert 200 toward a corner cutting edge 242 when viewed from the distal end side along a central axis AX1.

A technology capable of improving the accuracy of true-circular machining while avoiding an occurrence of intermittent cutting. A control unit of a machine tool determines an intermediate center position (Pi) in the moving direction for each divided rotation angle (E) smaller than a single rotation of the spindle and an intermediate eccentric radius (ri) around the intermediate center position (Pi) according to an initial position (Po) of the cutting edge in contact with the workpiece in the moving direction, the eccentric center position (Pc), and the eccentric radius (rc) to keep the cutting edge in contact with the workpiece as the moving object moves in the moving direction within a predetermined maximum feed speed (F) until a true-circular machining around the eccentric center position (Pc) is complete on the workpiece.

Damping elements for tool chucking systems for damping vibrations and shocks that occur during machining in the case of force-fitting clamping of tools in a tool receptacle or on the tool itself. At least one damping element consisting of a shape memory alloy having a mechanical effect is provided in a tool chucking system or on the tool itself, such that the damping element provided in the chucked state in the force flow of the chucked elements is present in a reversible and hysteresis-dependent state by way of a mechanical force action and the associated crystalline conversion via the pretensioning of said damping element and leads to dissipation of mechanical energy. The mechanical energy to be damped is a cyclical vibration or represents a non-cyclical overload which is transmitted in the form of shocks.

In a cutting tool having an indexable cutting insert with three cutting portions, the cutting insert is removably securable to an insert holder by means of a fastener. The cutting insert has two opposing end surfaces with a peripheral side surface extending therebetween. At least one end surface has a central boss protruding therefrom with a raised support surface, and the peripheral side surface has three abutment recesses. In an end view of the cutting insert, each of the three abutment recesses is visible and located inside a first imaginary circle circumscribing the visible central boss. A holding portion of the insert holder has a seating surface with at least one protuberance protruding therefrom. The support surface is in clamping contact with the seating surface, and exactly two of the three abutment recesses are engaged with the at least one protuberance.

A cutting tool holder has a holder body and a vibration damping weight assembly. The holder body has opposing first and second side surfaces and a top surface extending therebetween, and an insert mounting portion located at a front end of the holder body adjacent to the top surface. A weight aperture opens out to the first and second side surfaces and has an aperture inner surface. The weight assembly is located within the weight aperture, having a first and second weight portions, a damping ring located along the aperture inner surface, and an actuating member interfacing and urging the first and second weight portions away from one another, such that each weight portion presses against the damping ring within the weight aperture.

A polycrystalline CVD synthetic diamond work piece for use in a polycrystalline CVD synthetic diamond tool, the polycrystalline CVD synthetic diamond work piece comprising: a working surface; and a rear mounting surface; wherein an average lateral grain size of the rear mounting surface is no less than 10 m, and wherein the working surface comprises: (a) smaller diamond grains than the rear mounting surface; (b) an average lateral grain size in a range 10 nm to 15 m; and (c) a Raman signal generated by a laser focused on the working surface which exhibits one or more of the following characteristics: (1) an sp3 carbon peak at 1332 cm.sup.1 having a full width half-maximum of no more than 8.0 cm.sup.1, (2) an sp2 carbon peak at 1550 cm.sup.1 having a height which is no more than 20% of a height of an sp3 carbon peak at 1332 cm.sup.1 after background subtraction when using a Raman excitation source at 633 nm; and (3) an sp3 carbon peak at 1332 cm.sup.1 is no less than 10% of local background intensity in a Raman spectrum using a Raman excitation source at 785 nm.

A surface-coated cutting tool includes a base material and a coating formed on a surface of the base material. The coating includes a first hard coating layer including crystal grains having a sodium chloride-type crystal structure. The crystal grain has a layered structure in which a first layer composed of nitride or carbonitride of Al.sub.xTi.sub.1-x and a second layer composed of nitride or carbonitride of Al.sub.yTi.sub.1-y are stacked alternately into one or more layers. The first layer each has an atomic ratio x of Al varying in a range of 0.76 or more to less than 1. The second layer each has an atomic ratio y of Al varying in a range of 0.45 or more to less than 0.76. The largest value of difference between the atomic ratio x and the atomic ratio y is 0.05x-y0.5.

A surface-coated cutting tool includes a base material and a coating formed on a surface of the base material. The coating includes a first hard coating layer including crystal grains having a sodium chloride-type crystal structure. The crystal grain has a layered structure in which a first layer composed of nitride or carbonitride of Al.sub.xTi.sub.1-x and a second layer composed of nitride or carbonitride of Al.sub.yTi.sub.1-y are stacked alternately into one or more layers. The first layer each has an atomic ratio x of Al varying in a range of 0.76 or more to less than 1. The second layer each has an atomic ratio y of Al varying in a range of 0.45 or more to less than 0.76. The largest value of difference between the atomic ratio x and the atomic ratio y is 0.05x-y0.5.