A rotary cutting tool that implements a chip space in proportion to a feed-per-tooth is proposed. The rotary cutting tool includes a cutting part in which a plurality of cutting teeth and flutes are alternately formed, wherein a cross-section of the cutting part perpendicular to a central axis is divided into a plurality of cutting tooth spaces defining a section between cutting edges of adjacent cutting teeth on the basis of the central axis, such that all of the cutting tooth spaces are designed in different sizes, or some of the plurality of cutting tooth spaces are set in different sizes from the other cutting tooth spaces.

A tool assembly includes a first selectively flexible tool including a first plurality of sequentially arranged links moveable between a slacked position and a tensioned position; and a second selectively flexible tool including a second plurality of sequentially arranged links moveable between a slacked position and a tensioned position, the second plurality of sequentially arranged links moveable over or through the first plurality of sequentially arranged links.

A tool assembly includes a first selectively flexible tool including a first plurality of sequentially arranged links moveable between a slacked position and a tensioned position; and a second selectively flexible tool including a second plurality of sequentially arranged links moveable between a slacked position and a tensioned position, the second plurality of sequentially arranged links moveable over or through the first plurality of sequentially arranged links.

A machining tool incorporates a shaft having a first end configured to fit into a machining collet. A cutting portion extends from a second end of the shaft. A residual stress inducer is located between the first and second ends and includes a torsion element joined to the shaft at a connection end. A carbide tip is present on a free end opposite the connection end and the torsion element is configured such that a selected rotational speed, altered from a normal cutting speed, causes the carbide tip of the torsion element to contact a workpiece surface.

A drill head includes a first attachment surface attached to a holder, a head tip surface opposite to the first attachment surface in an axial direction along the central axis, and a head outer peripheral surface continuous with the first attachment surface and the head tip surface. The head outer peripheral surface is provided with a first flute and a second flute extending helically about the central axis from the head tip surface to reach the first attachment surface. The first flute and the second flute are symmetric with respect to the central axis. Each of the first flute and the second flute has a first end and a second end that face each other with a space between them in a circumferential direction along a circumference centered on the central axis.

A modular drill apparatus (100) includes: a shank (110) having a pocket (112); a cylindrical post (117) centrally secured within a bottom (114) of the pocket (112); a cutting tip (130) including a lower portion (131) including a central bore (136) which receives the cylindrical post (117), an upper portion (132) and a channel (134) therebetween; and an insert assembly (150) interfitted within and supported by the channel (134), the insert assembly (150) being expandable along a length thereof for securing the cutting tip (130) to the shank (110) within the pocket (112) by providing an interference fit and retractable along the length thereof for releasing the cutting tip (130) from the pocket (112) by overcoming the interference fit.

A modular drill apparatus (100) includes: a shank (110) having a pocket (112); a cylindrical post (117) centrally secured within a bottom (114) of the pocket (112); a cutting tip (130) including a lower portion (131) including a central bore (136) which receives the cylindrical post (117), an upper portion (132) and a channel (134) therebetween; and an insert assembly (150) interfitted within and supported by the channel (134), the insert assembly (150) being expandable along a length thereof for securing the cutting tip (130) to the shank (110) within the pocket (112) by providing an interference fit and retractable along the length thereof for releasing the cutting tip (130) from the pocket (112) by overcoming the interference fit.

A drill has a first main body portion and a second main body portion. The first main body includes a chip discharging surface, a flank face, and an outer peripheral surface. A ridgeline between the chip discharging surface and the flank face constitutes a cutting edge. The chip discharging surface has an auxiliary flute surface provided in a form of a helix around a center axis, the auxiliary flute surface being contiguous to the cutting edge, the auxiliary flute surface being recessed in a direction opposite to a rotation direction of the drill. An auxiliary cutting edge portion has a first end portion and a second end portion. When viewed in a direction along the center axis, a value obtained by dividing the maximum value of the diameter of the second main body portion by the diameter of the first main body portion is 1.5 or more.

There is provided a drill insert for drilling metallic or other materials, comprising a drill insert body with first and second lands at the outside diameter of the body that interface with the wall of a drilled hole. There is provided a coolant relief arrangement at the outside diameter of the drill insert by a plurality of coolant supply channels extending between the leading edge and trailing edge of the interface, to provide coolant relief to the outside diameter of the drill insert at the interface with the drilled hole. The drill inserts of the invention provide reduced friction and heat generation while maintaining high stability, and operate to prevent accumulation of materials on surfaces of the drill inserts at the outside diameter of the drill insert. This enables higher penetration rates and operating speeds while maintaining integrity of the drill inserts.

A rotary cutting tool according to the present disclosure is rotatable about an axial line and includes a rake face and a flank face. The flank face is contiguous to the rake face. A ridgeline between the rake face and the flank face constitutes a cutting edge. In a cross section perpendicular to the axial line, the rake face is constituted of a plurality of straight line portions.