A cutting insert has: an upper surface; a lower surface; a side surface, having a first surface and a second surface disposed opposite each other between the upper surface and the lower surface; and a first cutting edge. The lower surface has a plurality of slots extending from a side of the first surface to a side of the second surface. In addition, when viewed from a side of the lower surface, if the angle between a ridge line on which the upper surface and the first surface intersect and an imaginary extension line of the plurality of slots is defined as θ1, and the angle between a ridge line on which the lower surface and the first surface intersect and the imaginary extension line is defined as θ2, then θ2>θ1.

A rotary cutting tool includes a rotary tool body, a blade clamp, a cutting insert, a clamp fastener, and an insert fastener, wherein the rotary tool body has an insert pocket to define a bottom positioning face, a first lateral positioning face and a second lateral positioning face. The cutting insert is affixed to the blade clamp via the insert fastener. The first lateral positioning face is orientated opposite to a side cutting edge of the cutting insert. The blade clamp is slid into the insert pocket in an axial direction of the rotary tool body, wherein the blade clamp is coupled by the first and second lateral positioning faces in an interference clamping manner and is retained at the rotary tool body by the clamp fastener. The present invention has the advantages of strong radial impact resistance, high positioning accuracy, high safety concern and long service life.

A blade positioning structure of a disposable milling cutter includes a cutter body and a disposable blade. The cutter body is peripherally provided with a blade seat. By passing a screw through the disposable blade and the blade seat, the disposable blade is locked to the blade seat. The blade seat has a blade seat surface and a sidewall; the blade seat surface has a groove; the disposable blade has a bottom surface provided with a projection corresponding in shape to the groove; and when the disposable blade is locked to the blade seat, the blade seat surface and the groove of the latter lie respectively and tightly against the bottom surface and the projection of the former.

Provided are a cutting insert and a tool holder on which the cutting insert is provided. The cutting insert includes a circular upper surface, a circular lower surface, a cylindrical lateral surface for connecting the upper surface and the lower surface, an upper cutting edge formed between the upper surface and the lateral surface, a lower cutting edge formed between the lower surface and the lateral surface, and a plurality of rotation-preventing parts provided at the lateral surface so as to prevent the cutting insert from rotating with respect to the tool holder. Each rotation preventing part includes an inner curved surface recessed toward the center of the lateral surface and convexly rounded so as to form concentric circles in conjunction with the lateral surface, and a stepped rotation-preventing surface parallel to the axial direction of the insert and connecting the inner curved surface and the lateral surface.

Chip discharge control is further improved. A cutting insert includes an upper surface, a lower surface, a screw hole having an axis penetrating from the upper surface to the lower surface, a peripheral side surface, and a major cutting edge, a wiper edge, and an inner edge formed in an intersecting region between the upper surface and the peripheral side surface. In a side view in which the peripheral side surface on which the inner edge is formed is seen from a direction perpendicular to the axis, the inner edge includes a recessed part recessed toward the lower surface, a length D.sub.L of the inner edge on one side of the recessed part in the side view is longer than a length D.sub.R of the inner edge on the other side of the recessed part, a lowest point of the inner edge is at a position lower than a flat part of the upper surface, and at least a part of the inner edge on the one side is at a position higher than the flat part of the upper surface. A cutting edge angle φ.sub.23L of the inner edge on the one side of the recessed part is larger than a half of a cutting edge angle φ.sub.23R of the inner edge on the other side of the recessed part.

Chip discharge control is further improved. A cutting insert includes an upper surface, a lower surface, a screw hole having an axis penetrating from the upper surface to the lower surface, a peripheral side surface, and a major cutting edge, a wiper edge, and an inner edge formed in an intersecting region between the upper surface and the peripheral side surface. In a side view in which the peripheral side surface on which the inner edge is formed is seen from a direction perpendicular to the axis, the inner edge includes a recessed part recessed toward the lower surface, a length D.sub.L of the inner edge on one side of the recessed part in the side view is longer than a length D.sub.R of the inner edge on the other side of the recessed part, a lowest point of the inner edge is at a position lower than a flat part of the upper surface, and at least a part of the inner edge on the one side is at a position higher than the flat part of the upper surface. A cutting edge angle φ.sub.23L of the inner edge on the one side of the recessed part is larger than a half of a cutting edge angle φ.sub.23R of the inner edge on the other side of the recessed part.

This disclosure relates to a metal-cutting machine tool with a base body, which is rotatable about an axis of rotation relative to a workpiece to be machined, at least one plate seat disposed outside the axis of rotation on the base body and a cutting insert, which is inserted into the plate seat and held therein by at least one fastening means and which is provided with a coating, at least in the area of its cutting edge. In order to compensate for positional tolerances, according to this disclosure the plate seat comprises a positioning surface oriented toward the axis of rotation, and the cutting insert has a reference surface lying against the positioning surface and facing away from the axis of rotation, for radially determining the position of its cutting edge, wherein the coating is also applied to the reference surface.

A cutting body rotatable about a tool axis has an insert receiving pocket with a seat surface at an axial forward end thereof. The seat surface has a plurality of abutment elements, including an axial abutment element having an axially forward facing abutment surface and at least one radial abutment element. In a top view of the insert receiving pocket, the axially forward facing abutment surface forms an external acute clamping angle with a radially outward facing pocket wall. A rotary cutting tool includes the cutting body, and a cutting insert removably secured in the insert receiving pocket, having a base surface in contact with the seat surface. The at least one radial abutment element occupies or is occupied by at least one radial abutting element of the base surface, and the axially forward facing abutment surface is in contact with an axial abutting surface of the base surface.

A cutting insert has opposing upper and lower surfaces interconnected by a peripheral side surface, an insert axis passing through the upper and lower surfaces, and first and second upper cutting edges formed at the intersection of the upper surface and the peripheral side surface. A lower central protuberance having first, second, third and fourth abutment walls extends downwardly from the lower surface. In a cross-section taken in a first horizontal plane perpendicular to the insert axis and intersecting the lower central protuberance, the first, second, third and fourth abutment walls define an imaginary quadrilateral having diagonally opposing first and third internal angles and diagonally opposing second and fourth internal angles. The first and third internal angles are equal to each other, and the second and fourth internal angles are not equal to each other. Two cutting inserts are removably secured in a rotary cutting tool.

A cutting insert has opposing upper and lower surfaces interconnected by a peripheral side surface, an insert axis passing through the upper and lower surfaces, and first and second upper cutting edges formed at the intersection of the upper surface and the peripheral side surface. A lower central protuberance having first, second, third and fourth abutment walls extends downwardly from the lower surface. In a cross-section taken in a first horizontal plane perpendicular to the insert axis and intersecting the lower central protuberance, the first, second, third and fourth abutment walls define an imaginary quadrilateral having diagonally opposing first and third internal angles and diagonally opposing second and fourth internal angles. The first and third internal angles are equal to each other, and the second and fourth internal angles are not equal to each other. Two cutting inserts are removably secured in a rotary cutting tool.