The invention relates to a reamer (3), having a main body (5) and at least one cutting tip (1) arranged on the main body (5), the cutting tip (1) having a reamer section (7), the cutting tip (1) having, at a distance (A) from the reamer section (7), a roughening section (9) having at least one roughening blade (11), the at least one roughening blade (11) protruding beyond the reamer section (7) by a particular projection (D).

A reamer incudes a core and a plurality of outer-circumference cutting edges provided on an outer circumference of the core and made of a hard tool material. The core extends from a front end to a rear end. The core is provided with a plurality of flutes from the front end to the rear end. A center-of-gravity adjustment portion, which adjusts a distance from a center of rotation to a center of gravity, is provided at least partially from terminal ends of the plurality of flutes on a rear end side to the rear end of the core. The center-of-gravity adjustment portion causes the deviation of the center of gravity from the center of rotation to be smaller than when no center-of-gravity adjustment portion is provided.

A reamer incudes a core and a plurality of outer-circumference cutting edges provided on an outer circumference of the core and made of a hard tool material. The core extends from a front end to a rear end. The core is provided with a plurality of flutes from the front end to the rear end. A center-of-gravity adjustment portion, which adjusts a distance from a center of rotation to a center of gravity, is provided at least partially from terminal ends of the plurality of flutes on a rear end side to the rear end of the core. The center-of-gravity adjustment portion causes the deviation of the center of gravity from the center of rotation to be smaller than when no center-of-gravity adjustment portion is provided.

A reamer includes a core, a plurality of outer-circumference cutting edges provided on an outer circumference of the core and made of a hard tool material, and a margin provided on a rear side of each the plurality of outer-circumference cutting edges in a rotational direction. A distance from an axis of rotation to a position of a center of gravity of the reamer is greater than 0.01 mm and not greater than 0.5 mm.

A reamer includes a core, a plurality of outer-circumference cutting edges provided on an outer circumference of the core and made of a hard tool material, and a margin provided on a rear side of each the plurality of outer-circumference cutting edges in a rotational direction. A distance from an axis of rotation to a position of a center of gravity of the reamer is greater than 0.01 mm and not greater than 0.5 mm.

A reamer incudes a core and a plurality of outer-circumference cutting edges provided on an outer circumference of the core and made of a hard tool material. The core extends from a front end to a rear end. The core is provided with a plurality of flutes from the front end to the rear end. A center-of-gravity adjustment portion, which adjusts a distance from a center of rotation to a center of gravity, is provided at least partially from terminal ends of the plurality of flutes on a rear end side to the rear end of the core. The center-of-gravity adjustment portion causes the deviation of the center of gravity from the center of rotation to be smaller than when no center-of-gravity adjustment portion is provided.

Provided is a taper reamer with which it is possible to achieve an improvement in machining accuracy and machining life. The taper reamer comprises a plurality of cutting edges each having a helical shape provided on the outer periphery of a cutting-edge portion having an external diameter being expanded from a front end toward a rear end thereof, wherein an intertooth angle, defined between each of a pair of the cutting edges adjacently arranged in a circumferential direction, is different from one another at any given reference position, and wherein the plurality of cutting edges each have a helix angle that is different from one another. As the plurality of cutting edges that are unequally partitioned each have the helix angle that is different from one another, a resonance during cutting can be prevented.

A multi-edge reamer has a cutting region having a main body with a central axis. A first number of first cutters and a second number of second cutters extend from the main body. Each first cutter has a cutting edge and an adjoining circular grinding chamfer which forms a guide region for a corresponding first cutter and has a first width. Each second cutter has a cutting edge and an adjoining circular grinding chamfer which forms a guide region for a corresponding second cutter and has a second width. The first width is greater than the second width, the first number of first cutters is greater than the second number of second cutters, and all of the first cutters directly adjoin one another when seen in the circumferential direction so as to be arranged in a continuous group.

In order to achieve as highly accurate an alignment of the reamer as possible and therefore as high a drilled hole quality as possible during the precision machining of a drilled hole, the cutting edges of the reamer are divided into two cutting groups, the cutting edges of which are spaced apart with respect to one another in each case by an axial spacing from one another. Here, the axial spacing is selected in such a way that, at a predefined first, slower feed speed, merely the cutting edges of the first cutting edge group are in engagement with the workpiece and, at a higher, predefined second feed speed, all cutting edges are in engagement with the workpiece.

A multi-edge reamer has a cutting region having a main body with a central axis. A first number of first cutters and a second number of second cutters extend from the main body. Each first cutter has a cutting edge and an adjoining circular grinding chamfer which forms a guide region for a corresponding first cutter and has a first width. Each second cutter has a cutting edge and an adjoining circular grinding chamfer which forms a guide region for a corresponding second cutter and has a second width. The first width is greater than the second width, the first number of first cutters is greater than the second number of second cutters, and all of the first cutters directly adjoin one another when seen in the circumferential direction so as to be arranged in a continuous group.