A cutting insert including first cutting edges and second cutting edges respectively formed in a first end surface and a second end surface which are opposed to each other; at least one groove formed in a peripheral side surface which connects the first end surface and the second end surface; and, while one end of the groove reaches the first end surface, another end thereof reaches the second end surface, and an opening width in the first end surface is different from an opening width in the second end surface.

An end mill machining apparatus, a CAM apparatus, an NC program, and a machining method which suppress regenerative self-excited vibration and mode-coupling self-excited vibration. An end mill machining apparatus includes an end mill, and a control section for controlling the end mill. The ratio of the protrusion length of the end mill to the diameter of the end mill falls within a range of 5 to 50. The end mill is a variable pitch, uniform helix type or a variable helix type. The control section controls the end mill such that the contact angle between the end mill and a workpiece M1 during machining becomes equal to or smaller than a critical contact angle .sub.lim.

A rotating tool includes a tool body which rotates around an axial line, four or more chip discharge grooves which are formed on an outer periphery of the tool body with gaps therebetween in a circumferential direction, and a plurality of cutting inserts which are arranged in multiple stages along the chip discharge grooves. In a cross-sectional view perpendicular to the axial line, when a center angle formed between a pair of virtual straight lines which connects each of the cutting edges of the cutting inserts disposed in a pair of chip discharge grooves adjacent to each other in the circumferential direction and the axial line to each other is defined as an angle, a plurality of angles formed around the axial line include one maximum angle (max), one minimum angle (min), and two or more angles other than the angle (max) and the angle (min).

A end mill includes: an end mill body having a rotation axis, the end mill body including a shank portion and a cutting portion with an outer peripheral cutting edge; an end cutting edge including a first cutting edge and a second cutting edge; a first gash opening between the first cutting edge and the second cutting edge; and a second gash located adjacently to the first gash in the rotational direction, and opening to a side closer to the outside peripheral from the chisel portion. A ratio (L1/L2) of a length (L1) from a distal end of the end mill body to a terminal end of the first gash to a length (L2) from the distal end of the end mill body to a terminal end of the second gash, when viewed from a side, is from 0.8 to 1.1.

In one aspect, rotary cutting tools are described comprising clearances with projections adjacent the cutting edge and extending the width and length of the clearance surface of each tooth. This design can assist in reducing vibration or chatter during cutting operations.

An assembly of a tool and a tool holder may include the tool, which may have an elongated body with a socket, and the tool holder, which may have a body with a first bore configured to receive at least a portion of the elongated body, and a second bore substantially transverse to the first bore. The assembly may also have an impinging member including a body having an end with a radial surface. In an assembled state, a portion of the elongated body of the tool may be positioned within the first bore of the body of the tool such that the socket and the second bore may be substantially aligned, and the body of the impinging member may be positioned within the second bore with the radial surface pressed against the elongated body in the socket at a predetermined torque.

An indexable rotary cutting tool comprising, a twist angle of the outer peripheral cutting edge having a positive value, an axial rake angle of the cutting edge of the corner R at a boundary point between the cutting edge of the corner R and the outer peripheral cutting edge has a positive value, the axial rake angle of the cutting edge of the corner R at the reference point has a negative value, at least the radial rake angle in a region between the boundary point and the reference point in an entire edge length region of the cutting edge of the corner R has a negative value, and the radial rake angle of the cutting edge of the corner R at the reference point is smaller than the radial rake angle of the cutting edge of the corner at the boundary point.

An anti-vibration damper for tools for machining of metallic work pieces is provided. For improving the damping in order to be more effective under rough includes a vibration damping device received in a hollow cylindrical space of a tool member. The vibration damping device includes a plurality of rotationally symmetrical stacked on top of each other to form a stack. A part of mutually facing upper and lower surfaces of adjacent members is spaced at a distance from each other by elastically deformable elements. The outer diameter of the stack is smaller than the inner diameter of the hollow cylindrical space of the tool member, thereby providing a cylindrical gap, which is substantially filled with spherical balls, wherein clear gap width between the inner diameter of the hollow cylindrical space and the common outer diameter of the stack deviates from any integer sum of the ball diameters.

A movable axial element for a damping system includes a rectilinear absorbent mass positionable in the housing and having at least one annular groove arranged on a periphery of the absorbent mass and in which at least one elastic element is arranged to bear against an internal wall of the housing. The at least one groove includes a base formed by a shoulder of the absorbent mass. An edge formed by a structure bearing an annular lip is mounted in a sliding manner on at least one part of the shoulder along at least one axis of the movable element to form an adjusting device integrated into the movable element to enable the control of a prestressing exerted by the annular lip on the elastic element mounted on the periphery of the absorbent mass, the prestressing being generated without rotation of the annular lip relative to elastic element.

A cutter holder has a body and a damping assembly. The damping assembly is contained inside the body. The damping assembly has a central damping pole and six auxiliary damping poles. The six auxiliary damping poles are arranged around the central damping pole. The body has a specific weight. The central damping pole has a specific weight larger than the specific weight of the body. Each one of the six auxiliary damping poles has a specific weight larger than the specific weight of the body. The damping assembly is utilized to reduce vibrations caused by machining.