A cutting tool having a cutting edge member which forms at least one corner part, wherein a material for the cutting edge member is selected from either diamond, an ultrahigh-pressure sintered body containing cubic boron nitride or a PVD or CVD coating applied to a surface of the ultrahigh-pressure sintered body. At least part of an intersecting edge between an end surface of the cutting edge member and a peripheral side surface thereof is provided with a cutting edge. A chip breaker comprising a breaker wall surface is formed in the end surface of the cutting edge member. The breaker wall surface has at least one projected surface part which bulges outwardly from the cutting tool. As viewed from the end surface, the recessed surface part is arranged so as to be apart from a virtual plane A which is defined so as to divide the corner part into halves.

A cutting insert according to an aspect includes a base portion and a cutting portion. The cutting portion includes a front end surface, an top surface, a first lateral surface, a second lateral surface, a front cutting edge, and a lateral cutting edge. The front cutting edge includes a first cutting edge and a second cutting edge, and a radius of curvature of the first cutting edge is greater than a radius of curvature of the second cutting edge.

There is provided a cutting insert having a low possibility that chips roughen a machined surface of a workpiece in back turning. The cutting insert includes a rake surface, a peripheral side surface, a front cutting edge which is provided on a ridge of the rake surface and the peripheral side surface, and a main cutting edge which is provided on the ridge so as to be continuous with the front cutting edge and has an extension direction which forms an obtuse angle with an extension direction of the front cutting edge, the main cutting edge is curved into a U shape over an entire length of an effective edge range which functions as a cutting blade, and the deepest point of the U shape is positioned in a range closer to a side of a corner than a position which divides a straight line connecting both ends of the main cutting edge at a ratio of 2:1 from the side of the corner positioned adjacent to the front cutting edge.

A cutting insert in a non-limiting aspect of the present disclosure may include an upper surface, a lower surface, a lateral surface and a cutting edge. The upper surface may include a first corner and a first side. The upper surface may further include a rake surface, a bottom surface and a raised surface. The bottom surface may include a first bottom surface and a second bottom surface. The first bottom surface may be located on a bisector of the first corner. The second bottom surface may be located inwardly of the first side. The first bottom surface may be an inclined surface located closer to the lower surface as going away from the first corner. The second bottom surface may be an inclined surface located further away from the lower surface as going away from the first side.

A cutting insert may include an upper surface, a lateral surface, and a cutting edge including a boundary between the upper surface and the lateral surface. The upper surface may include a first rising face that extends upward and a second rising face that is connected to an upper side of the first rising face and extends upward. The first rising face may include a first region that extends along a corner portion and a second region that extends along a side portion. The second rising face may include a third region connected to the first region and a fourth region connected to the second region. An entirety of a boundary between the first region and the third region may be positioned above the cutting edge. A boundary between the second region and the fourth region may include a portion disposed below the cutting edge.

There is provided a cutting tool in which chip control is improved. A cutting edge member includes a first wall surface which includes a concave surface which is formed to be depressed in a direction away from an intersection point of an imaginary plane and a corner portion and toward the center of a cutting insert in an end view when viewed from a direction facing an end surface, a second wall surface which includes a convex surface which is provided to be connected to the first wall surface at a position spaced apart from the imaginary plane and is protruded in a direction away from the center of the cutting insert in the end view, a third wall surface which includes a convex surface which is provided to be connected to the first wall surface at a position spaced apart from the imaginary plane on an opposite side to the second wall surface across the imaginary plane and is protruded in a direction away from the center of the cutting insert in the end view, and a fourth wall surface which is provided in an area between the first wall surface and the intersection point in the end view, includes a convex surface which is protruded in a direction away from the center of the cutting insert in the end view, and has a height smaller than heights of the second wall surface and the third wall surface in a side view when viewed from a direction facing a side surface.

It is intended to allow a wide range including a low region (fine finishing) to a middle region (medium cutting) to be covered with a single insert. A cutting insert includes an upper surface, a lower surface, a peripheral side surface, a cutting edge including a main cutting edge and a corner cutting edge, a corner portion, a projecting portion formed to extend from the corner portion toward a central axis and including a first projection and a second projection, a rake portion, and an inclined portion provided at the cutting edge. The inclined portion has a first inclined portion beginning at an intermediate point in the corner cutting edge, while the rake portion has a shape in which an angular degree of a rake angle gradually increases with distance from the corner portion.

A cutting insert may include a first surface, a second surface and a third surface. The first surface may include a corner having a convex curvilinear shape and an inclined surface. The inclined surface may include a first inclined surface, a second inclined surface and a third inclined surface. The first inclined surface may be inclined at a first angle. The second inclined surface may be inclined at a second angle. The third inclined surface may be inclined at a third angle. The first inclined surface may have a concave curvilinear shape in a cross section orthogonal to a bisector of the corner. The second inclined surface may be a flat surface. The second angle may be smaller than either of the first angle and the third angle in a cross section which includes the bisector and is orthogonal to the reference plane.

A turning insert includes a top surface, an opposite bottom surface, and a reference plane located parallel to and between the top and the bottom surfaces. A nose portion includes a convex nose cutting edge, and a first and a second cutting edge. The nose cutting edge connects the first and second cutting edges. The first and second cutting edges form a nose angle of 71-85° relative to each other. The nose portion has a third convex cutting edge adjacent to the first cutting edge and a fourth cutting edge adjacent to the third convex cutting edge. The fourth cutting edge forms an angle of 10-30° relative to a bisector. The distance from at least a portion of the fourth cutting edge to the reference plane increases at an increasing distance from the nose cutting edge. A second protrusion is arranged between the nose cutting edge and the first protrusion.

A drill includes drill body and peripheral insert having a radial cutting edge extending generally in a direction of a radius of the drill body, and a central insert. The peripheral insert includes a rake face including a plurality of chipbreaker protrusions. A first angle measured between a line tangent to forward ends of the plurality of chipbreaker protrusions and the central axis of the drill body extending toward the shank end is an acute angle. Also a peripheral insert is disclosed.