A boring tool has a cutting insert, a holder, and a pressing member. The cutting insert includes a base member and a cutting member. The base member includes a first side surface, a second side surface, a third side surface, and a fourth side surface. The holder includes a front end surface, a rear end surface, and an outer peripheral surface. The holder is provided with a first hole and a second hole. The first hole is opened in the front end surface. The second hole is opened in the outer peripheral surface. The holder includes a stopper. A surface defining the second hole includes a first inner side surface and a second inner side surface. The pressing member is in contact with the fourth side surface in a state in which the pressing member is disposed in the first hole.

To perform machining on a workpiece under wider variety of machining conditions. A first rising surface is adjacent to a cutting portion across a first surface, the first rising surface being inclined upward away from the first surface in a direction along a center axis and being away from the center axis toward a rear end of a main body. A second rising surface extends from a second surface toward the rear end of the main body, and is inclined upward away from the second surface in the direction along the center axis. In the direction along the center axis, a rear end of the first rising surface is closer to the rear end of the main body than a front end of the second rising surface.

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 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 boring-bar arrangement includes a boring bar, a securing device, and a clamping bolt. The securing device has a reduction sleeve, which is secured in a tool chuck, which has a front end that faces away from the tool chuck and a protruding hollow section which receives the boring bar. The hollow section has a hollow-section interior, a hollow-section outer wall, and a hollow-section wall which is arranged therebetween. The hollow-section wall has a first thickness in a side region where the cutting tool protrudes from the boring bar which is less than a second thickness in a rest of the hollow-section wall. The boring bar is releasably secured as a replaceable head, via its back end, at a front end of the protruding hollow section. A front end of the clamping bolt has a male thread which sits in the female thread of the boring bar.

A tool having a toolholder and a cutting insert disposed in the pocket of the toolholder. The cutting insert includes a hole having a cutting insert clamping surface that is contacted by the clamp clamping surface. The clamp clamping surface and the cutting insert clamping surface are formed, such that as a clamp bottom surface is moved toward a bottom surface of the pocket, when a post is in a post hole and a fastener is in a clamp hole and a toolholder hole, the cutting insert is urged against the bottom surface and a rear wall. A tool holder is also disclosed.

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.

A tool for machining a workpiece. The tool comprises a cutting insert with a shank, which extends along a cutting insert longitudinal axis, and with at least one cutting edge, wherein at least a part of the cutting insert is made of a first material. The tool further comprises a tool holder which extends along a holder longitudinal axis and comprises on an end-face end a cutting insert receptacle for receiving the cutting insert shank, wherein the cutting insert receptacle is designed as a cup-shaped recess in the tool holder. The tool further comprises an attachment element which is fixedly connected to the cutting insert and extends in a circumferential direction around the cutting insert shank, wherein at least a part of the attachment element is made of a second material which differs from the first material. Still further, the tool comprises a fastening element for fastening the cutting insert on the tool holder, wherein, in a mounted state of the tool, the fastening element contacts the attachment element in order to fasten the cutting insert on the tool holder.

A body of a cutting tool and a cutting insert which can further improve support stiffness of the cutting insert are provided.

A body of a cutting tool includes an insert seat provided on a leading end part of the body, a screw hole with which a fastening screw is screwed, a deep seat portion provided at a deep part in the insert seat in an axial direction of the screw hole, a receiving portion receiving a contact portion of the cutting insert, a wall portion having a base-end side rotation suppression portion which stops rotation of the cutting insert, and a shallow seat portion, the depth of a seat thereof being shallower than a part with the receiving portion, wherein the base-end side rotation suppression portion is positioned not to overlap the deep seat portion when viewed along a screw-hole axis.