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 structure includes a shank part and a flute part arranged on one end of the shank part. A chisel edge is formed on the front end of the flute part and two drill blades with tilt directions toward the shank part are formed on the two sides of the chisel edge. Every drill blade includes a primary relief surface with a cutting edge and a secondary relief surface with a knife-back edge. At least one assist relief surfaces is formed on the inner wall of one of the two helical grooves and an included angle is between the assist relief surface and the horizontal plane. The assist relief surface is connected with the cutting edge of one drill blade and portion of the knife-back edge of another drill blade.

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 rotary cutting tool includes a main body, a shank portion having a rearward end, and a flute portion having a forward end with one or more flanks. One or more connecting fluid holes are in fluid communication with a central fluid hole and terminates at a flank at the forward end of the cutting tool. One or more twisted fluid holes extend through a lobe in the flute portion and terminates at a flank at the forward end of the cutting tool. A cross-sectional shape of the connecting fluid holes and the twisted fluid holes is selected to provide enhanced delivery of fluid to the cutting edge. In one aspect, the rotary cutting tool is a modular drill and the flute portion has a pocket for holding a replaceable cutting insert.

The invention relates to a rock drill comprising an insertion portion, a flute adjoined to the insertion portion, and a head portion adjoined to the flute, wherein the flute is of at least double-spiral configuration and correspondingly has at least two substantially spiral discharge grooves, to which respectively two substantially spiral flute webs forming the lateral groove walls are assigned. It is proposed that a constant spiral pitch is assigned to the first discharge groove, inclusive of the lateral groove walls thereof, along the drill longitudinal axis, and that at least one of the two flute webs assigned to the first discharge groove has or have along the drill longitudinal axis, at least in sections, a web spine width which changes, in particular, alternately.

In order to ensure good guidance of a drilling tool at the start of a drilling operation and at the same time ensure a reliable evacuation of a center chip, in the drill bit, in a tool flank adjoining a respective main cutting edge, an additional point thinning is recessed in the region of a transverse cutting edge, which additional point thinning, extending in a principal direction from the tool flank, merges, with a convex course, into a chip flute. As a result of the convex design, an as far as possible homogeneous, edge-free transition into the chip flute is obtained. Since the point thinning is additionally made, the tool flank, even in the rear end facing away from the cutting edge, remains at a front axial position, so that a second land is effective for a reliable guidance of the bore already at an axially front position.

A step drill bit can include a cutting head defining a longitudinal axis and multiple steps having different effective diameters. First and second cutting edges can be formed in the cutting head. The first cutting edge and the second cutting edge can be arranged such that the bit is asymmetric in a plane perpendicular to the longitudinal axis relative to a plane containing the longitudinal axis. The step drill bit can further include one or more flutes. Each flute can define a groove in the cutting head that extends along a helical path about the longitudinal axis. Each flute can have a variable helix angle such that the angle of the helix about the longitudinal axis changes at one or more points along the length of the flute.

A drilling tool for producing drill holes includes a tip and a shaft arranged opposite the tip in a direction of a longitudinal axis of the drilling tool. The drilling tool has at least one geometrically defined cutting edge in the tip area, and has an expanded diameter trailing the tip in a longitudinal direction from the tip. The drilling tool has a first area with a first diameter that precedes the expanded diameter, and a second area with a second diameter, larger than the first diameter, that trails the expanded diameter. The drilling tool is distinguished in that the expanded diameter and/or the second area is/are embodied such that chips are produced in the area of the expanded diameter and/or in the second area when a workpiece is machined, chips consistent with those produced when a workpiece is machined with a geometrically undefined cutting edge.

A drill has a replaceable cutting head mounted to a shank in an interlocking fashion. The shank has a pocket with at least one flat, vertically-angled retention surface located closer to a rotational axis than at least one driving surface. Similarly, the cutting head has at least one vertically-angled retention surface located closer to the rotational axis of the drill than at least one driven surface. As a result of the relative locations between the surfaces with respect to the rotational axis, the stresses and fatigue imposed on the drill are minimized, thereby prolonging tool life.

A drill with a cutting fluid supply hole includes: a tool main-body with an axial end cutting-edge, a portion having a discharge flute on a main-body distal end side portion, and a cutting fluid supply hole, the hole having a fan-shaped cross section defined by a front inner-wall surface located along a main-body radial direction on the front side in the drill rotation direction, a rear inner-wall surface located along the radial-direction on the rear side in the drill rotation direction and facing the front inner-wall surface in a main-body circumferential direction, an outer circumferential inner-wall surface made up of a partially cylindrical surface around a drill center line, and an inner circumferential inner-wall surface made up of a partially cylindrical surface around the center line with a curvature radius smaller than that of the outer circumferential inner-wall surface and facing the outer circumferential inner-wall surface in the radial direction.