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.

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 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 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.

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.

A drill bit has a tool shank, a center axis, a first cutting region with at least one geometrically defined first cutting edge, the same having a cutting face arranged at a radial distance from the center axis of the drill bit. The first cutting edge forms a countersink angle with the center axis. The drill bit having a chip shaping stage functionally assigned to the first cutting edge formed by the cutting face of the first cutting edge and by a shoulder surface adjoining the cutting face and forming a shoulder angle with the same, wherein the shoulder angle is greater than 90°, and preferably greater than 100°. The cutting face runs at a radial rake angle with respect to an imaginary radial line which cuts the first cutting edge, the same functionally assigned to the cutting face. The radial rake angle is positive.

A drill bit has a tool shank, a center axis, a first cutting region with at least one geometrically defined first cutting edge, the same having a cutting face arranged at a radial distance from the center axis of the drill bit. The first cutting edge forms a countersink angle with the center axis. The drill bit having a chip shaping stage functionally assigned to the first cutting edge formed by the cutting face of the first cutting edge and by a shoulder surface adjoining the cutting face and forming a shoulder angle with the same, wherein the shoulder angle is greater than 90°, and preferably greater than 100°. The cutting face runs at a radial rake angle with respect to an imaginary radial line which cuts the first cutting edge, the same functionally assigned to the cutting face. The radial rake angle is positive.