A drill bit comprising: a tubular shaft having a cutting tip at a first end and a drive shank at a second end, wherein the drive shank is adapted to engage with a drive motor, and wherein the cutting tip comprises an axially protruding shape. A first flute portion positioned between the cutting tip and the drive shank, wherein the first flute portion includes a first thread with a first sharpened cutting edge in a first helix; and wherein the first end of the cutting tip has a point angle greater than 135 degrees, and the cutting tip includes a cutting surface that joins to the first thread, and wherein the cutting tip act as a bit driver and has a profile, when viewed axially from the first end has one shape type.

The drill (1) is provided with a drill body (2) having a rotation center axis (O), two cutting edges (3) provided on the tip side of the drill body (2), and chip evacuation flutes (10) provided behind the two cutting edges (3) in the direction of rotation of the drill (1) from the two cutting edges, the drill tip angle () being from 170 to 190, the web thickness (d) being from 0.10 to 0.25 times the drill diameter (D), the opening angle () of the chip evacuation flutes (10) being from 85 to 110, and the drill (1) comprising a curve having a radius of curvature that gradually decreases from the cutting edge side wall surface (14) to the heel side wall surface (15) of the chip evacuation flutes (10) in a cross-section at a position where the chip evacuation flutes (10) are present.

A device for opening a connection to a lined pipe is disclosed. The device has a body that includes a front end and a rear end and being rotatable about a rotation axis. The device also has a drill head that has multiple cutters for puncturing and enlarging a hole in a liner, and multiple side cutters have at least one cutting edge parallel to the rotation axis. A safety ring is disposed on the body between the drill head and the side cutters. The safety ring has a circular periphery extending beyond the drill head and the side cutters in a direction perpendicular to the rotation axis.

A method for designing a cutting edge of a cutting element configured for removing material from a workpiece to leave therein a desired end profile (B22,B24,B26). The method comprises the steps of modeling a desired end profile (B22,B24,B26) of the workpiece, the profile having a longitudinal axis and being defined by a bottom surface (B12), a side surface (B16) and an adjustment surface (B14) extending therebetween; defining a lead profile plane (RP.sub.L) and an trail profile plane (RP.sub.T) spaced therefrom, each of the planes being oriented perpendicular to the longitudinal axis; determining a profile contour defined by the intersection line between the end profile (B22,B24,B26) and the lead profile plane (RP.sub.L). The contour profile includes a bottom contour, an adjoining contour and a side contour defined as the intersection lines between the lead profile plane (RP.sub.L) and the bottom surface (B12), the adjustment surface (B14) and the side surface (B16) respectively; designing a rake surface and a relief surface, the intersection line between which defines a cutting edge lying in the adjoining surface (B14) and spanning between the lead profile plane (RP.sub.L) and the trail profile plane (RP.sub.T). The cutting edge is designed such that in any reference plane (RP; FIG. 6A) oriented perpendicularly to the cutting edge, the intersection between each of the rake surface and the relief surface with the reference plane (RP) defines a respective rake line (RK; FIG. 7) and relief line (RF; FIG. 7), the angle (.sub.B) between the lines RK,RF) being equal to or smaller than a similar angle (.sub.B) taken along each of a plurality of similar reference planes (RP) disposed between the reference plane (RP.sub.n) and the lead profile plane (RP.sub.L).

A twist drill having a shaft with a longitudinal axis, wherein the cutting tool includes a plurality of flutes extending about the longitudinal shaft along a helix angle and a plurality of lands adjacent the flutes. Each land has a cutting edge adjacent a corresponding flute and a margin (i.e. relief surface). A cutting point is adjacent a forward end of the shaft. A first, second and third forward cutting surfaces are adjacent the first, second and third cutting edges, respectively, and extend proximate the cutting point axially rearward for a predetermined length about the longitudinal axis of the shaft. The cutting edges are unequally angularly spaced from each other, and each forward cutting surface has a primary relief angle that are unequal to each other.

A device for opening a connection to a lined pipe is disclosed. The device has a body that includes a front end and a rear end and being rotatable about a rotation axis. The device also has a drill head that has multiple cutters for puncturing and enlarging a hole in a liner, and multiple side cutters have at least one cutting edge parallel to the rotation axis. A safety ring is disposed on the body between the drill head and the side cutters. The safety ring has a circular periphery extending beyond the drill head and the side cutters in a direction perpendicular to the rotation axis.

A fluted drill comprises, in axial sequence, a body portion, and a cutting portion. The cutting portion comprises two or more cutting edges, with each cutting edge extending from a distal end of the cutting portion, along the cutting portion towards the body portion, to the body portion.

Each cutting edge has a first rake angle at the distal end of the cutting portion, progressively increasing to a third rake angle at a proximal end of the cutting portion. Each cutting edge has a first uncut chip thickness at the distal end of the cutting portion, progressively decreasing to a third uncut chip thickness at the proximal end of the cutting portion.

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.

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.

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.