According to the present disclosure, a cutting insert includes an upper surface having a polygonal shape and includes a corner, a side surface adjacent to the upper surface, a cutting edge and a protrusion. The cutting edge is located at a ridge part in which the upper surface intersects with the side surface and includes a corner part located at the corner. The protrusion is located on the upper surface. The protrusion includes a first protrusion on a bisector of the corner in a top view. The protrusion further includes a second protrusion adjacent to the first protrusion in a direction orthogonal to the bisector. The second protrusion is closer to the corner than the first protrusion in the top view.

A machine tool includes a main spindle that rotates while holding a workpiece, a holder that holds first and second cutting tools including first and second linear cutting blades to cut the workpiece, and a moving device that moves the first and second cutting tools relative to the workpiece in a moving direction including at least a Z-direction and a Y-direction. The holder holds the first and second cutting tools such that the cutting tools are arranged along the moving direction in a state in which the directions of the linear cutting blades are inclined with respect to the Z-direction when seen from the X-direction and are not parallel with each other.

A machine tool includes a main spindle that rotates while holding a workpiece, a holder that holds first and second cutting tools including first and second linear cutting blades to cut the workpiece, and a moving device that moves the first and second cutting tools relative to the workpiece in a moving direction including at least a Z-direction and a Y-direction. The holder holds the first and second cutting tools such that the cutting tools are arranged along the moving direction in a state in which the directions of the linear cutting blades are inclined with respect to the Z-direction when seen from the X-direction and are not parallel with each other.

A boring tool holder has a base member and a cutting insert holding member. The base member has a first main surface and a second main surface opposite to the first main surface. The cutting insert holding member is contiguous to the base member on the first main surface, and disposed in a circumferential direction of the base member as viewed in a direction from the first main surface toward the second main surface. A cross-sectional area of the base member in a cross section perpendicular to the direction from the first main surface toward the second main surface and intersecting the base member is larger than a cross-sectional area of the cutting insert holding member in a cross section perpendicular to the direction from the first main surface toward the second main surface and intersecting the cutting insert holding member.

A boring tool holder has a base member and a cutting insert holding member. The base member has a first main surface and a second main surface opposite to the first main surface. The cutting insert holding member is contiguous to the base member on the first main surface, and disposed in a circumferential direction of the base member as viewed in a direction from the first main surface toward the second main surface. A cross-sectional area of the base member in a cross section perpendicular to the direction from the first main surface toward the second main surface and intersecting the base member is larger than a cross-sectional area of the cutting insert holding member in a cross section perpendicular to the direction from the first main surface toward the second main surface and intersecting the cutting insert holding member.

In a method for a finishing work of a spray-coated surface, an inner surface of a cylindrical hollow member is roughened by forming a helical groove thereon. A thermal spray coating is formed on the inner surface that is roughened, and a finishing work is carried out by cutting the thermal spray coating along a helix of the groove by use of a cutting tool. According to the method for a finishing work, a finishing work of a thermal spray coating with non-uniform hardness can be carried out efficiently.

A cutting insert and a cutting tool having same. The cutting insert includes: an upper surface; a lower surface having a flat surface; a fastening hole penetrating the upper surface and the lower surface; side surfaces each connecting to the upper surface and the lower surface; and cutting edges formed by the upper surface and the side surfaces. A first cutting edge is inclined downward. A major side surface comprises a first major side surface connected to the upper surface so as to constitute the first cutting edge, and a second major side surface connected to the first major side surface and the lower surface. A minor side surface comprises a first minor side surface connected to the upper surface so as to constitute a second cutting edge, and a third minor side surface connected to the upper surface and the lower surface.

A cutting insert and a cutting tool having same. The cutting insert includes: an upper surface; a lower surface having a flat surface; a fastening hole penetrating the upper surface and the lower surface; side surfaces each connecting to the upper surface and the lower surface; and cutting edges formed by the upper surface and the side surfaces. A first cutting edge is inclined downward. A major side surface comprises a first major side surface connected to the upper surface so as to constitute the first cutting edge, and a second major side surface connected to the first major side surface and the lower surface. A minor side surface comprises a first minor side surface connected to the upper surface so as to constitute a second cutting edge, and a third minor side surface connected to the upper surface and the lower surface.