An insert includes an upper surface including at least one corner part and a plurality of side parts, and a side surface. The upper surface includes a corner region. The corner region includes a first corner surface, a second corner surface, a third corner surface, and a fourth corner surface which are located sequentially in order from a side of the corner part. The first corner surface is inclined downward. The second corner surface, the third corner surface and the fourth corner surface are inclined upward. An inclination angle 12 of the second corner surface is greater than an inclination angle 13 of the third corner surface. An inclination angle 14 of the fourth corner surface is greater than the inclination angle 12 of the second corner surface.

In an embodiment, a cutting insert includes an upper surface, a front end surface, and a front cutting edge. The upper surface includes a first protrusion and a second protrusion, and a first surface, a second surface, and a third surface, each of which is located between the first protrusion and the second protrusion. The first surface is inclined downward at a first inclination angle. The second surface is inclined upward at a second inclination angle. The third surface is inclined upward at a third inclination angle. The second surface is located lower than an upper end of each of the first protrusion and the second protrusion. The third surface extends further upward than the upper end of each of the first protrusion and the second protrusion. The third inclination angle is smaller than the second inclination angle.

Provided is a fastening structure having a wide application range and a high degree of freedom of design. A fastening structure includes: a head including a first end surface and a first screw part formed on the first end surface; and a shank including a second end surface and a second screw part formed on the second end surface and threadedly engaging with the first screw part. The first end surface includes a first principal surface oriented in an axial direction of the first screw part and a first step surface oriented in a rotational direction of the first screw part. The second end surface includes a second principal surface oriented in an axial direction of the second screw part and a second step surface oriented in a rotational direction of the second screw part. The first and second principal surfaces face each other and the first and second step surfaces face each other when the first screw part threadedly engages with the second screw part.

A turning tool includes a tool body extending along a tool axis and having a base on a tip of the tool body, a cutting insert detachably attached to the base, and a measurement device attached to the tool body. The measurement device has a first distance sensor which measures a distance to an object located radially outward of the tool axis.

A production method for a ring-shaped part is provided with: an inner cutting step for reciprocating a first cutting blade in the radial direction D4 from a state of contact with the center of the thickness of one end 91a of a rotating cylindrical blank 91 and moving toward the other end 91b in the axial direction D1 to form a semicircular track while cutting the inner circumferential R1-side of the cylindrical blank 91; an outer cutting step before, after or simultaneously with the inner cutting step for reciprocating a second cutting blade in the radial direction D4 from a state of contact with the center of the thickness of the one end 91a of the rotating cylindrical blank 91 and moving toward the other end 91b in the axial direction D1 to form a semicircular track while cutting the outer circumferential R2-side of the cylindrical blank 91; and a separation step after the inner cutting step and the outer cutting step for cutting the portion 92 of the cylindrical blank 91, the inner circumferential R1-side and the outer circumferential R2-side of which have been cut, from the remainder 93 of the cylindrical blank 91 to obtain a ring-shaped part 94 with a roughly circular cross-section.

A cutting insert may include a base member and a coating layer. The base member may include a first and second surface. The coating layer may be located on the base member. The coating layer may include a first layer containing -aluminum oxide, which is located above the first surface and the second surface. The first layer may include a first region located above the first surface, and a second region located above the second surface. When an angle formed by a normal line of a crystal plane (001) of the -aluminum oxide in the first layer and a normal line of the surface of the base member is a first inclination angle, a peak of a distribution of the first inclination angle in the first region is located at a lower angle side than a peak of a distribution of the first inclination angle in the second region.

There is provided a cutting insert used for both drilling and turning. The cutting insert includes an insert main body having a front surface and a rear surface, the outline shapes of which are parallelogram shapes, peripheral side surfaces disposed on four sides of the insert main body, cutting edges provided on respective intersecting ridge lines between the front surface and the peripheral side surface and between the rear surface and the peripheral side surface of the insert main body, and a hole provided in the insert main body to incline with respect to the front surface and the rear surface, the hole being usable for attachment.

A cutting tool, a turning machine including the cutting tool, and an associated method are provided. The cutting tool includes a tool, a cutting head, a strain gauge, and an accelerometer. The cutting head is located at the tool bar and has a cutting edge. The strain gauge measures strain at the tool bar. The accelerometer measures acceleration at the tool bar or the cutting head. Deflection of the cutting edge is estimated based on output from the strain gauge and the accelerometer. In some embodiments, the accelerometer is arranged close to the cutting edge, while the strain gauge is arranged where the tool bar is susceptible to the largest strain. In some embodiments, low frequency vibrations of the cutting edge are estimated based on measured strain, high frequency vibrations are estimated based on measured acceleration, and medium frequency vibrations are estimated based on output from both sensor types.

A cutting tool, a turning machine including the cutting tool, and an associated method are provided. The cutting tool includes a tool bar extending along an axis, a cutting head located at the tool bar, and at least one sensor integrated with the tool bar or the cutting head. A rotational orientation of the cutting tool with respect to the axis is estimated based on output provided by the at least one sensor. In at least some embodiments, the at least one sensor includes accelerometers configured to measure acceleration in at least two directions.

A production method for a ring-shaped part is provided with: an inner cutting step for reciprocating a first cutting blade in the radial direction D4 from a state of contact with the center of the thickness of one end 91a of a rotating cylindrical blank 91 and moving toward the other end 91b in the axial direction D1 to form a semicircular track while cutting the inner circumferential R1-side of the cylindrical blank 91; an outer cutting step before, after or simultaneously with the inner cutting step for reciprocating a second cutting blade in the radial direction D4 from a state of contact with the center of the thickness of the one end 91a of the rotating cylindrical blank 91 and moving toward the other end 91b in the axial direction D1 to form a semicircular track while cutting the outer circumferential R2-side of the cylindrical blank 91; and a separation step after the inner cutting step and the outer cutting step for cutting the portion 92 of the cylindrical blank 91, the inner circumferential R1-side and the outer circumferential R2-side of which have been cut, from the remainder 93 of the cylindrical blank 91 to obtain a ring-shaped part 94 with a roughly circular cross-section.