A blade section has two lands and two flutes in an alternating manner and also has a linear chisel edge. The lands are each provided with: a margin section that is continuous with a cutting blade; a clearance section that is continuous with the margin section and that has a smaller diameter than the margin section; and a pad that is continuous with the clearance section and that has the same width as the width of the margin section.

In the drill, each of the thinning edges extends beyond an intersection point with the chisel; an axial rake angle is in a range of +5 to +15; and a ratio of a length of each of the thinning edges to a length of each of the cutting edges in a direction, in which the main cutting edge extends as viewed from the front side of the axial direction, is in a range of 20% to 50%. Intersecting ridges between: second thinning wall surfaces facing an opposite side of the drill rotation direction; and the tip flank faces, are disposed that: they are spaced apart in a direction orthogonal to the intersecting ridges; they are positioned on one diameter line passing the axis; or they mutually pass over in a passing over amount of 0.03D or less with respect to a diameter of the cutting edges.

A drill of the present invention includes: a drill main body; a plurality of convex-arc cutting edges which are formed on a tip side of the drill main body from an outer periphery of the drill main body to a chisel edge provided near to a rotational axis; second faces which are each formed in an approximately band shape and are each formed along each of the convex-arc cutting edges on a back side of the convex-arc cutting edge in the rotational direction; third faces which are each formed to be continuous with a back side of each of the second faces in the rotational direction; and fourth faces which are each formed to be continuous with a back side of each of the third faces in the rotational direction.

A drill has a central axis, a front side, a circumferential surface, at least two main edges on the front side, which reach up to the circumferential surface and merge there with secondary edges, at least two central edges extending from the end of the main edge facing away from the circumferential surface, cutting surfaces associated with the main edges and central edges, chip flutes associated with the main edges and central edges and introduced into the circumferential surface, at least one cross edge adjoined by the ends of the central edges facing away from the main edges which passes through the central axis, a point thinning and chip run-up shoulders associated with at least the cutting surfaces of the central edges. An angle of the chip run-up shoulder decreases in the region of the point thinning towards the central axis as the distance from the front side increases.

A rotary tool (2) is provided, comprising: a main blade (4), a chip flute (6), a lateral surface (8), a flank (10) trailing the main blade (4) and extending from the main blade (4) up to the lateral surface (8) and to the chip flute (6), wherein the flank (10) comprises a kink (12) and is thus concave in configuration, wherein the kink (12) extends from the lateral surface (8) up to the chip flute (6) and thus divides the flank (10) into a leading partial surface (14) and a trailing partial surface (16). The invention further relates to a method for manufacturing such a rotary tool (2).

A drill bit cutter and a drill bit are disclosed. The drill bit cutter defines a rotation axis and includes two cutter parts located at two sides of the rotation axis in a transverse direction, each cutter part having a front cutter face, a rear cutter face, and a blade formed between the front cutter face and the rear cutter face. The front cutter face of each cutter part is ground to form a ground shaped face. The ground shaped faces of the two front cutter faces are different, At least a local height difference is thereby produced in the two blades. Drilling precision can be increased while extending cutter life.

According to one implementation, a drill includes the first cutting edges, the second cutting edges and a deflection reducer. The first cutting edges drill a prepared hole to a workpiece. The first cutting edges are formed in a tip side of the drill. The first point angle and each first relief angle of the first cutting edges continuously or intermittently decrease from the tip side toward a rear end side of the drill. The second cutting edges finish the prepared hole. The second cutting edges are formed at positions away in the rear end side from the first cutting edges. The second cutting edges have the second relief angles at a maximum diameter position. The deflection reducer reduces deflection of the second cutting edges. The deflection reducer is formed between the first cutting edges and the second cutting edges. The deflection reducer is inserted into the prepared hole.

A method is specified for producing a rotary tool (2) having a base body (4), which extends in a longitudinal direction (L) and in which at least one flute (6) is ground in by grinding in a first partial flute (12A) with a first helix angle (W1) in a first grinding step and by subsequently grinding in a second partial flute (12B) with a second helix angle (W2) in a second grinding step, the second helix angle differing from the first helix angle (W1) so that a flute (6) that expands in the longitudinal direction (L) is formed, wherein the two partial flutes (12A, 12B) are ground in using the same grinding wheel (11). In this way, a particularly quick production is realized. Furthermore, a corresponding rotary tool (2) is specified.

A drill reamer (20) comprises an elongate body (21) disposed about a longitudinal axis. The elongate body comprises flutes (22a-22d) having separate hard cutting sections (27a, 28a, 28a, 28b, 28b) and a soft cutting section (24a, 24b). The soft cutting section is formed of a material such as carbide having a hardness that is less than that of the hard cutting sections, which may be formed of polycrystalline diamond. At least one first hard cutting section (27a) is axially displaced relative to at least one second hard cutting section (28a, 28a). The reamer has a tip cutting edge (23a, 23c) and tapered cutting edge portions (24a-24d) disposed at an acute angle relative to the longitudinal axis.

A single-lip drill including at least one cutting edge on a drill head has a face which is concave along at least 75 percent of the width thereof and substantially along the entire length thereof, all the way to, and inclusive of, the cutting edge.