A drill includes a bar-shaped drill body, a major cutting edge which is located at a front end of the drill body and has a straight-line region in a front view, a rake surface located along the major cutting edge, and a chip discharge flute being extended spirally around a rotation axis of the drill body in a direction from the rake surface toward a rear end of the drill body. The rake surface has a flat region located along the straight-line region.

A drill bit includes a shank, a transition portion, and a body portion defining a plurality of axially stacked, progressively sized steps. The steps include a first step and a terminal step coupled to the transition portion. The first step defines two tip flutes each disposed at a tip flute angle. The body portion defines a body flute extending from the first step to the transition portion. The drill bit also includes an indicator band formed on a portion of the body flute and a portion of an outer surface of one of the plurality of steps.

A tool shank has a head receiving pocket at a forward end, and a plurality of chip flutes extending rearwardly therefrom along a longitudinal axis. The head receiving pocket has a support surface transverse to the longitudinal axis. A central recess is formed in the support surface and extends rearwardly therefrom. The central recess has a plurality of resiliently displaceable abutment portions circumferentially alternating with and spaced apart by a plurality of intermediate portions. Each abutment portion has a radially inward facing abutment surface, and each intermediate portion has an intermediate surface intersecting two circumferentially adjacent abutment surfaces. A rotary cutting tool includes the shank and a cutting head releasably mounted thereto. The cutting head has a mounting portion provided with a base surface and an engagement member protruding therefrom. In an assembled position, the engagement member is resiliently retained in the central recess against the plurality of abutment surfaces.

A drill has a helical flute surface, a flank face, and a thinning face. A ridgeline between the thinning face and the flank face constitutes a thinning cutting edge. The thinning cutting edge has a curved thinning cutting edge portion and a straight thinning cutting edge portion. The curved thinning cutting edge portion protrudes forward in the rotation direction. The straight thinning cutting edge portion is contiguous to the curved thinning cutting edge portion. The curved thinning cutting edge portion has a first end portion and a second end portion. The first end portion is a boundary between the curved thinning cutting edge portion and the straight thinning cutting edge portion.

An instrument comprising a shank and a working portion, the working portion having a tip and a plurality of flutes being defined by at least two lands having a land margin; wherein the working portion has a parabolic cross-section defining opposing convexed surfaces extending between at least two opposing land margins.

The invention relates to a drill tip (2) comprising a base body (6) having chip flutes (22A,B) and extending in the axial direction along an axis of rotation (8) and having at least two main cutting edges (14A,B) on the front face thereof extending outward in the radial direction to a cutting corner (16A,B). Seen in cross section, the base body is asymmetric relative to rotation about the axis of rotation (8) at the height of the cutting corner (16A,B). The cross section of the base body is simultaneously designed having symmetrical spacing from the main cutting edges (14A,B). The drill tip (2) is in particular designed as an interchangeable modular part of a modularly designed drill tip (5). A drill base body (4) in which the drill tip (2) can be inserted can therefore in turn be designed symmetrically.

A drill includes a drill body rotatable about a drill axis, and a cutting portion. The cutting portion includes a first grinding face having first and second chisel edges defining an angle therebetween, and a second grinding face having third and fourth chisel edges defining an angle therebetween, the second grinding face being point-symmetrical with the first grinding face. A first relief face associated with a first cutting edge extends from the first and fourth chisel edges and a second relief face associated with a second cutting edge extends from the second and third chisel edges. A first intersection line is formed where the first and second relief faces meet; a second intersection line is formed where the third and fourth relief faces meet. The first and second intersection lines are spaced apart from an imaginary center line passing through the rotational axis and the first and third relief faces.

In an embodiment, a drill includes a bar-shaped body rotatable around a central axis. The body includes a first surface located at a first end, a second surface intersecting with the first surface on a front side in a rotation direction, and a cutting edge located at an intersection of the first surface and the second surface. The second surface includes a first region located along the cutting edge, and a second region located on a front side in the rotation direction with respect to the first region. The second surface has a concave shape in a cross section orthogonal to the central axis.

Devices for broken drill bit removal are provided herein. The drill bit includes a center through hole situated longitudinally and interiorly in the drill bit. A wire rope first end is welded to a cutting tip of the drill bit and retained freely within the walls of the center through hole and said wire rope having a stop attached at a second end. Should the drill bit be compromised, leaving the portion of drill bit head lodged in the bore, the pieces of drill bit are still connected via said wire rope and the lodged portion can be easily and quickly removed by pulling and backing out the powered device that was driving the drill bit thus alleviating the necessity of EDMing the broken drill bit out of the bored component.

A drill is provided with a flank at a leading end portion of a body. An oil hole is provided at the flank, having a fan-shaped cross-section. The fan-shaped cross-section is formed by being surrounded by a front-side inner wall surface, a rear-side inner wall surface, an outer peripheral-side inner wall surface, and an inner peripheral-side inner wall surface. Compared to a round hole, a discharge performance of cutting fluid of the oil hole is high. The rear-side inner wall surface curves in a circular arc shape toward the front in a rotation direction. Thus, the drill can secure a distance between a ridge section of the flank and the rear-side inner wall surface to be wide, can suppress stress acting on a section between the ridge section of the flank and the oil hole, and can thus increase a discharge amount of the cutting fluid and also secure a tool rigidity.