A cutting insert for machining has a substantially cylindrical main body with an axis, a lateral flank and opposing rake faces. Cutting edges are formed at the intersection of the flank and rake faces. The cutting edges have, in the direction of the axis, in each case at least two convexly curved sections which are connected together by concavely curved or substantially straight sections.

A cutting insert comprises an upper surface including a first corner, and a second and third corner, respectively, adjacent to both sides of the first corner. The upper surface sequentially includes a rake surface along an upper cutting edge, inclined toward a lower surface, going inward from the upper cutting edge at a rake angle on a basis of a perpendicular plane perpendicular to a central axis extending between the upper and lower surfaces, and a connection surface more inward than the rake surface, inclined toward the lower surface, going inward at a connection angle on the basis of the perpendicular plane. An intersecting part of the rake surface and the connection surface includes a highest position in a portion of the intersecting part corresponding to a minor rake surface. A cutting tool with cutting insert, and a method of producing a machined product using the cutting tool are provided.

The technical objective of the present invention is to provide a cutting insert that has an improved fastening property with a cutting tool, thereby preventing reduction of the service life. To this end, the cutting insert according to the present invention has three corners along the circumference thereof; an upper main cutting edge, which is formed on the edge between the upper surface and the first side surface, and an upper sub cutting edge, which is formed on the edge between the upper surface and the second side surface, are continuously disposed between respective corners; the lower surface has the same shape as that of the upper surface; and the angle defined between the upper main cutting edge and the upper sub cutting edge, which are placed on both sides with reference to each corner, is larger than or equal to 85? and is smaller than 90?.

A cutting insert according to an embodiment of the present invention has an upper surface, a lower surface, a side surface connected to each of the upper surface and the lower surface, and a cutting edge located along an intersection of the upper surface and the side surface. The upper surface has a land surface disposed along the cutting edge, a rake surface which is located further inside than the land surface and is inclined so as to have a smaller height as departing from the land surface, and a bottom surface located further inside than the rake surface. The rake surface has a projection-shaped first region and a concave-shaped second region which are alternately disposed along the bottom surface. The first region has a first recess that reaches the second region adjacent to the first region.

A workpiece at least includes a first outer surface, a second outer surface and a third outer surface. The third outer surface intersects the first outer surface and the second outer surface to define an extrusion-acting portion having an extruding portion. The workpiece can be used to machine a cutter in an entire or a trimmed portion thereof. Thereupon, rapid production of cutters by molding machines can be realized, and blades of the molding machine for machining the cutter become replaceable. While a blade portion is machining, the extrusion-acting portion is applied to support and guide the workpiece, such that the surface machined by the blade portion can be extruded and polished simultaneously. Thus, machining qualities of the cutter, including finish, straightness and roundness, manufactured by applying the workpiece for the molding machine can be significantly improved.

A surface-coated cutting tool includes a base material and a coating. A hard layer in the coating includes a plurality of crystal grains having a sodium chloride-type crystal structure. When the angle of intersection between the normal direction to (111) plane that is a crystal plane of the crystal grain and the normal direction to the surface of the base material is measured, a proportion A of the crystal grains having the angle of intersection of 0 degree or more to less than 20 degrees is 50% or more. The length of 3 grain boundaries is less than 50% of the length of 3-29 grain boundaries. The crystal grain has a layered structure in which a first layer and a second layer are alternately stacked. The total thickness of the first layer and the second layer adjacent to each other is 3 to 40 nm.

A rotary milling tool has a tool holder and a milling head releasably attached thereto. The milling head has a head through recess opening out to the head forward and rearward surfaces. The recess includes a plurality of radially extending tooth-receiving lobes. The tool holder has a projection which includes a plurality of radially extending teeth. When assembled the teeth are located in the tooth-receiving lobes and provide centering and torque transfer capabilities.

A cutting insert and an indexable insert-type cutting tool includes a cutting edge (6A) formed on each of a pair of side ridge portions of at least one of the side faces, wherein an insert main body (1) is formed in the shape of having front-back inversion symmetry which is 180 rotationally symmetrical with respect to a line of symmetry (N) passing through the center of the side faces; a flank face adjacent to the cutting edge (6A) is formed on the side face in the vicinity of each of the pair of polygonal faces (2); each of the flank faces is formed in the shape of a twisted face; the pair of side ridge portions on which the cutting edge (6A) is formed intersect each other in such a manner that the second corner portion (B) of one side ridge portion protrudes outside the other side ridge portion.

A double-sided cutting insert that has a positive clearance face and includes a top portion, a bottom portion substantially identical to the top portion, and a middle portion. The inscribed diameter at the middle portion is larger than the inscribed diameter at each of the top portion and the bottom portion. The double-sided cutting insert having positive clearance face provides a simplified grinding method in order to achieve the dimensional precision required as well as reduced tooling cost allowing both positive and negative double-sided cutting inserts seat in the same insert-receiving pocket on the same tool holder.

In a cutting insert according to an embodiment of the present invention, an upper cutting edge includes, sequentially from a first corner to a second corner, a corner cutting edge, a minor cutting edge inclined as separating from the corner cutting edge at a first inclination angle on a basis of a vertical plane perpendicular to a central axis extending between upper and lower surfaces, and a major cutting edge inclined as separating from the minor cutting edge at a second inclination angle on the basis of the vertical plane so as to become more closer to the lower surface than the minor cutting edge. A cross section of a rake surface obtained by cutting an inwardly located end portion thereof along a direction of the central axis has a straight line shape or concave shape in a region crossing over at least a minor rake surface and a major rake surface. A cutting tool with the cutting insert, and a method of manufacturing a machined product by using the cutting tool are also provided.