For improving a drill, in particular a spiral drill, comprising a base body extending substantially longitudinally in a direction axial to a drill axis, said base body comprising a drilling portion, wherein a radially inward core region in relation to the drill axis and a radially outer region are provided in the base body in the drilling portion, and the drilling portion comprises a plurality of spiral-shaped recesses in the outer region, and arranged between each two spiral-shaped recesses is a wall part, it is proposed that the drill comprises at least four main cutting edges, in particular exactly four main cutting edge and/or the drill comprises at least three central cutting edge portions.

Cutting tool for the rotary machining of workpieces, in particular a twist drill, with a cutting tip which has at least one main cutting edge and at least one free surface (24), wherein a flank face adjoins the main cutting edge radially to the outside, and wherein a flank angle of the flank face increases in a radially outward direction.

The invention relates to a rotary tool (2) extending longitudinally from a shank region (8) to a front-facing end region along an axis of rotation (6) and having a carrier (4) with a plate seat (14) and a cutting insert (16) that can be replaceably inserted therein. The cutting insert (16) as well as the plate seat (14) each have radial and axial contact surfaces (40A, B) which are strained against one another with the aid of a clamping screw (50) during assembly of the cutting insert (16). According to the invention, it is provided that the axial contact surfaces (40A, B) and in particular also the radial contact surfaces (42A, B) are inclined in a V shape on one side of the cutting insert (16) and on the other side of the plate seat (14), so that a centering effect is automatically produced during assembly.

A drill according to a non-limiting aspect may have a body, a cutting edge, a rake face, and a groove. The cutting edge may have a curved chisel edge, a pair of first cutting edges, and a pair of second cutting edges. The second cutting edge may have a first portion extending from the chisel edge and a second portion extending from the first portion toward the first cutting edge. The rake face may have a first region extending from the first portion and a second region extending from the second portion. A first rake angle of the first region may be zero or a negative value. A second rake angle of the second region may be a negative value. An absolute value of the second rake angle may be greater than an absolute value of the first rake angle.

A drill includes a body. The body includes a first cutting edge, and a second cutting edge apart from the first cutting edge to the back end side relative to the first cutting edge and formed in a recess traversing an outer peripheral portion of the body. In a side view of the body in a first direction in which a distance between a center axis of the body and a first outer end of the first cutting edge is seen the longest, a second outer end of the second cutting edge is located at the center axis side relative to the first outer end of the first cutting edge.

A three-flute drill includes a body, discharge grooves, cutting edges, thinning edges and gash portions. The discharge grooves are provided in an outer peripheral surface of the body. The cutting edges are provided on ridge sections between inner faces of the discharge grooves and flanks of the body. The thinning edge extends from an end of the cutting edge toward a radially inner side. The gash portion includes an R portion and a straight portion. A first ridge line between the R portion and the flank extends while curving toward a rotation direction, from an end of the thinning edge toward a radially outer side. A second ridge line between the straight portion and the flank extends linearly from an end of the first ridge line toward the radially outer side, and connects to the discharge groove further to the radially inner side than the outer peripheral surface.

A threading insert includes a top surface, an opposite bottom surface, a side surface connecting the top surface and the bottom surface, and a first tooth. The first tooth has a first cutting edge, the first cutting edge including a first top cutting edge connecting a first leading cutting edge and a first trailing cutting edge. The first cutting edge has an edge roundness and the size of the edge roundness varies along the first cutting edge.

A vertical-edge double-step sawtooth cutter for preparing high-quality holes of composite material and thereof hybrid stack structure, and has three parts which are a major cutting edge region A, a minor cutting edge region B and a shank region C. The minor cutting edge region B comprises a step vertical-edge region D and a sawtooth cutting region E. This has the step structure and the sawtooth structure which is distributed in the first step, has a recutting function at the inlet and a reverse cutting function at the outlet in the direction opposite to the main cutting motion. The cutter has the vertical edge structure distributed in the second step, and the angle of the second step is a negative value, thereby realizing chip breaking and crushing, reducing scratch to the upper-layer composite material and metal hole walls.

A method is provided for processing a workpiece by means of a drill, wherein the drill extends along a longitudinal axis and has a drill tip with a nose angle (S) that is less than 180, wherein the drill has a lateral surface, on which at least one side blade is formed, which is designed for milling by means of a feeding in a transverse direction (Q) to the longitudinal axis (L), wherein the workpiece has a surface (O), through which a drill hole is drilled, in that in a first step a plane surface is milled into the surface (O) and subsequently in a second step the drill hole is drilled from the plane surface outwards, wherein the plane surface is milled by means of the side blade of the drill in that it is fed forward in a transverse direction (Q) to the longitudinal axis (L), wherein the drill hole is drilled by means of the same drill in that it is fed forward in the direction of the longitudinal axis (L). Further, a corresponding drill is provided.

A drill structure comprises a shank part and a bit part. A web is formed on the front end of the bit part. Two sides of the web are tilted backward to form two cutting faces. At least one chip-discharge groove is formed on the surface of the bit part. Each cutting face includes a primary cutting face and a secondary cutting face. The thickness of the prismatic web edge of at least one primary cutting face is smaller than the outer-side width of the primary cutting face. An auxiliary cutting face is extended to the wall of the flute from the cutting edge of the primary cutting face and a portion of a blade back of the secondary cutting face of another cutting face. The present invention decreases the drilling resistance during drilling a hole and increases the service life of the drill bit.