The upper surface includes a first breaker projection face extending along the first side surface, a second breaker projection face extending along the second side surface, and a rake face located between the first breaker projection face and the second breaker projection face in top view. In a direction from the rear surface to the front surface, a first front end of the first breaker projection face is located ahead of a second front end of the second breaker projection face. A cutting edge has a first cutting edge portion and a second cutting edge portion. In a direction perpendicular to the reference surface, the second breaker projection face is lower than the first breaker projection face, and a boundary between the first cutting edge portion and the second cutting edge portion is lower than the second breaker projection face.

A cutting insert (112) comprising a top surface (118), a bottom surface (120), and side surfaces (122) spanning there-between, said side surfaces (122) comprising one or more feed-facing side surfaces (122a) and one or more radial-facing side surfaces (122b). The top surface (118) is formed with one or more linear grooves, each constituting a chip breaker (125) and being disposed parallel to and adjacent one of said feed-facing side surfaces (122a). The chip breaker (125) is characterised by a constant profile along the entire length of its respective feed-facing surface (122a). Each of said feed-facing side surfaces (122a) is disposed at an acute feed-angle ( feed) with respect to the top surface (118), and each of said radial-facing side surfaces (122b) being disposed at an acute radial-angle ( radial) with respect to the top surface (118), the feed-angle ( feed) being greater than said radial-angle ( radial).

A cutting insert (112) comprising a top surface (118), a bottom surface (120), and side surfaces (122) spanning there-between, said side surfaces (122) comprising one or more feed-facing side surfaces (122a) and one or more radial-facing side surfaces (122b). The top surface (118) is formed with one or more linear grooves, each constituting a chip breaker (125) and being disposed parallel to and adjacent one of said feed-facing side surfaces (122a). The chip breaker (125) is characterised by a constant profile along the entire length of its respective feed-facing surface (122a). Each of said feed-facing side surfaces (122a) is disposed at an acute feed-angle ( feed) with respect to the top surface (118), and each of said radial-facing side surfaces (122b) being disposed at an acute radial-angle ( radial) with respect to the top surface (118), the feed-angle ( feed) being greater than said radial-angle ( radial).

A display device acquires and displays information on a machine tool that includes a spindle for relatively rotating workpiece and a cutting tool and feed axes for relatively feeding the workpiece and the cutting tool and that performs machining on the workpiece while making the cutting tool and the workpiece swing relatively, and includes: a first information display unit that displays first information indicating a position to which the cutting tool is relatively fed with respect to the workpiece; a second information display unit that displays second information indicating a relationship between the phase of the spindle and the positions of the feed axes; and a range selection unit that selects part of the first information as a selection range, and the second information display unit changes the display range of the second information such that the display range corresponds to the selection range selected by the range selection unit.

A display device acquires and displays information on a machine tool that includes a spindle for relatively rotating workpiece and a cutting tool and feed axes for relatively feeding the workpiece and the cutting tool and that performs machining on the workpiece while making the cutting tool and the workpiece swing relatively, and includes: a first information display unit that displays first information indicating a position to which the cutting tool is relatively fed with respect to the workpiece; a second information display unit that displays second information indicating a relationship between the phase of the spindle and the positions of the feed axes; and a range selection unit that selects part of the first information as a selection range, and the second information display unit changes the display range of the second information such that the display range corresponds to the selection range selected by the range selection unit.

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 an upper surface, a side surface, and a cutting edge. The upper surface may include a first breaker portion and a second breaker portion. The first breaker portion may include a first surface inclined downward and a second surface inclined upward. The second breaker portion may be inclined upward as the second breaker portion extends away from the first breaker portion. An inclination angle of the first surface may be constant along the first side portion. A length of the first surface may be greater at a second end portion than at a first end portion. An intersection portion of the first breaker portion and the second breaker portion may be orthogonal to the first side portion, or inclined away from the first corner portion as the intersection portion extends away from the first side portion.

A cutting insert may include a first surface, a second surface, a third surface and a cutting edge. The first surface may include a corner, a first side, a first inclined surface located along the corner, a second inclined surface located further inside than the first inclined surface, a third inclined surface located along the first side, a fourth inclined surface located further inside the first surface than the third inclined surface, and a protruded part located further inside than the second inclined surface and the fourth inclined surface. An inclination angle of the protruded part may be smaller than an inclination angle of the second inclined surface in a cross section along a bisector of the corner. The inclination angle of the protruded part may be larger than a third inclination angle in a cross section orthogonal to the first side.

A cutting tool for performing cutting of a relatively rotating external workpiece while relatively feeding the same in a specified direction is configured to have: cutting sections that have a tool edge, a base section, which is provided as one piece with or separate from the cutting sections and is for holding the cutting sections, a chip-guiding wall, which starts near a tool edge, is formed on the outer circumferential surface of the base section so as to extend in the direction moving away from the tool edge, and is for interfering with chips from the external workpiece and guiding the chips in a direction away from the tool edge. Provided thereby is a cutting tool capable of smoothly discharging chips during cutting.

A cutting tool for performing cutting of a relatively rotating external workpiece while relatively feeding the same in a specified direction is configured to have: cutting sections that have a tool edge, a base section, which is provided as one piece with or separate from the cutting sections and is for holding the cutting sections, a chip-guiding wall, which starts near a tool edge, is formed on the outer circumferential surface of the base section so as to extend in the direction moving away from the tool edge, and is for interfering with chips from the external workpiece and guiding the chips in a direction away from the tool edge. Provided thereby is a cutting tool capable of smoothly discharging chips during cutting.