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 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.

A drill has at least one main cutting edge (22) and a helical flute (20) abutting the main cutting edge (22). The surface of the flute (20) has a spiral segment (28) and an edge segment (30) abutting the main cutting edge (22). The roughness of the edge segment (30) is less than the roughness of the spiral segment (28). Furthermore, a method for producing a drill is provided.

A drilling tool includes a tool body having a center axis defining a longitudinal direction of the drilling tool. The tool body has an axially forward end and an axially rearward end, the distance in the longitudinal direction between the forward end and the rearward end defining a length of the drilling tool. At least two indexable cutting inserts are arranged at the axially forward end, a first indexable cutting insert being arranged at a radially inner position and a second indexable cutting insert being arranged at a radially outer position. The tool body includes a first flute portion extending axially rearward from the first indexable cutting insert and a second flute portion extending axially rearward from the second indexable cutting insert. The first flute portion transitions into the second flute portion at an axially forward transition area of the tool body, thereby forming only one flute of the tool.

A rotary cutting tool includes a tool body including a chip flute portion having a plurality of helical chip flutes separated by lobes. In one aspect, a tunable vibration absorber assembly is disposed within a cavity formed in the chip flute portion. In another aspect, the tunable vibration absorber assembly is disposed within a cavity of a replaceable cutting head. In each aspect, the tunable vibration absorber assembly includes at least two tunable absorber masses, a resilient material between the one or more absorber masses and the cavity, and one or more connecting members for preventing relative angular displacement of the one or more tunable absorber masses. The at least two tunable absorber masses are suspended only by the resilient material, thereby enabling the tunable vibration absorber assembly to be tuned to a desired frequency for suppressing torsional vibration of the rotary cutting tool during a cutting operation.

A cutting tool may include a main body extended from a first end to a second end. The main body may be rotatable around a rotation axis. The main body may include a first cutting edge, a second cutting edge, a first flute and a second flute. The first flute may be extended from the first cutting edge toward the second end. The second flute may be extended from the second cutting edge toward the second end. The first flute may include a first hole located in the main body. The second flute may include a second hole located in the main body. The first hole may have a circular shape and the second hole may have a long narrow shape in a circumferential direction of the rotation axis in a cross section orthogonal to the rotation axis.

An alloy tool bit twist drill, comprising a tool shank, a spiral tool body and an alloy tool bit . A groove is milled on a spiral cutting surface of the spiral tool body, the alloy tool bit is integrally arranged on the spiral cutting surface, the spiral cutting surface and a cutting surface of the alloy tool bitare arranged in the same groove, and a central stepped platform is arranged on the cutting surface near the axis center of the alloy tool bit. A central stepped surfaceis arranged on the inner side of the central stepped platform protruding in the rotating direction; or a branch hole table and a branch cutting surface are concavely arranged on the cutting surface of the alloy tool bitin a stepwise manner.

A drill bit for forming a round hole in a workpiece, includes a cylindrical shank having a longitudinally extending fluted portion with opposed first and second ends, and defining a longitudinal axis about which the shank is rotatable. The fluted portion includes opposed helical flutes formed in the cylindrical surface of the fluted portion of the shank and extending longitudinally along and between the first and second ends of the fluted portion. The helical flutes each define a concave surface intersecting with the cylindrical surface of the shank to form opposed flute edges. The first end of the fluted portion includes a cutting tip intersecting the helical flutes, wherein at least one of the flute edges has a concave cross-section extending from the second end toward the first end of the fluted portion.

A method for producing a twist drill has the following steps. A blank is shaped to form a semi-finished product. The semi-finished product is formed from a core, coaxial with the drill axis, having a radius and a number of webs, arranged on the core, having a height. The semi-finished product has a constant cross section along the drill axis. The webs have a first portion which adjoins the core and in which a width of the web remains constant or decreases in the circumferential direction with increasing radial distance from the drill axis. The webs have a second portion which adjoins the first portion and in which the width of the web increases in the circumferential direction with increasing radial distance from the drill axis. The webs of the semi-finished product are shaped into helical segments using a plurality of rolling tools that annularly enclose the semi-finished product and roll on the webs along the drill axis. The rolling tools have teeth that are inclined with respect to the drill axis. A height of the helical segments is less than the height the webs. Helical segments formed from adjacent webs are in contact with one another in a closing fold. The invention also relates to a twist drill.

A rotary cutting tool includes a tool body including a chip flute portion having a plurality of helical chip flutes separated by lobes. In one aspect, a tunable vibration absorber assembly is disposed within a cavity formed in the chip flute portion. In another aspect, the tunable vibration absorber assembly is disposed within a cavity of a replaceable cutting head. In each aspect, the tunable vibration absorber assembly includes at least two one or more tunable absorber masses, a resilient material between the one or more absorber masses and the cavity, and one or more connecting members for preventing relative angular displacement of the one or more tunable absorber masses. The at least two one or more tunable absorber masses are suspended only by the resilient material, thereby enabling the tunable vibration absorber assembly to be tuned to a desired frequency for suppressing torsional vibration of the rotary cutting tool during a cutting operation.