Abstract: A drill has a first main body portion and a second main body portion. The first main body includes a chip discharging surface, a flank face, and an outer peripheral surface. A ridgeline between the chip discharging surface and the flank face constitutes a cutting edge. The chip discharging surface has an auxiliary flute surface provided in a form of a helix around a center axis, the auxiliary flute surface being contiguous to the cutting edge, the auxiliary flute surface being recessed in a direction opposite to a rotation direction of the drill. An auxiliary cutting edge portion has a first end portion and a second end portion. When viewed in a direction along the center axis, a value obtained by dividing the maximum value of the diameter of the second main body portion by the diameter of the first main body portion is 1.5 or more.

Abstract: A reamer is rotated about a central axis and has, in a direction along a central axis, a tool front end and a tool rear end that is an end opposite to the tool front end. The reamer includes a blade on a tool front end side. The blade has, on a circumferential surface, a chamfered cutting edge located on the tool front end side, a circumferential cutting edge contiguous to an end of the chamfered cutting edge on a tool rear end side, and a margin that is a surface contiguous to the circumferential cutting edge. The circumferential cutting edge includes a front end portion between a first position and a second position, the first position being an end on a chamfered cutting edge side, the second position having a distance of 1 mm from the first position in a direction of extension of the circumferential cutting edge.

Abstract: A reamer is rotated about a central axis and has, in a direction along a central axis, a tool front end and a tool rear end that is an end opposite to the tool front end. The reamer includes a blade on a tool front end side. The blade has, on a circumferential surface, a chamfered cutting edge located on the tool front end side, a circumferential cutting edge contiguous to an end of the chamfered cutting edge on a tool rear end side, and a margin that is a surface contiguous to the circumferential cutting edge. The circumferential cutting edge includes a front end portion between a first position and a second position, the first position being an end on a chamfered cutting edge side, the second position having a distance of 1 mm from the first position in a direction of extension of the circumferential cutting edge.

Abstract: The drill is rotatable about a central axis. The drill includes a central axis, a front end and a rear end opposite to each other in a direction along the central axis, an outer peripheral surface, a cutting edge formed at the front end and extending from the outer peripheral surface toward the central axis, a flank face contiguous with the cutting edge, a flute formed on the outer peripheral surface and extending spirally around the central axis from the front end toward the rear end, and a thinning rake face contiguous with the flute. The cutting edge has a main cutting edge extending from the outer peripheral surface and a thinning cutting edge contiguous with an end of the main cutting edge away from the outer peripheral surface. The flute includes a main rake face contiguous with the main cutting edge from the opposite side of the flank face.

Abstract: The holder has a first surface and a second surface. The head includes a cutting edge portion and a shank portion. The holder is provided with a first hole and a second hole communicating with the first hole, the first hole extending in a third direction inclined by a second angle relative to a second direction extending from the second surface toward the first surface when viewed in a direction parallel to the axis line. The shank portion has a flat surface portion, and is provided inside the second hole. The fastening portion is provided inside the first hole, and is in contact with the flat surface portion. In a plane perpendicular to the axis line, a third angle between the second direction and a fourth direction perpendicular to the flat surface portion is larger than the second angle. The third angle is less than 90°.

Abstract: The negative land includes: a first region in which a space between the upper cutting edge and the lower cutting edge becomes wider toward the outer circumferential surface; and a second region which is continuous to the first region and in which the space becomes wider toward the rotation axis. In a cross section perpendicular to the rotation axis, the rake face includes a return face continuous to the outer circumferential surface, the return face being recessed opposite to a rotation direction of the drill. When a first boundary represents a boundary between the outer circumferential surface and the first region and a second boundary represents a boundary between the first region and the second region, a length of the first boundary is larger than a length of the second boundary in a direction parallel to the rotation axis. The second boundary is continuous to the return face.

Abstract: The negative land includes: a first region in which a space between the upper cutting edge and the lower cutting edge becomes wider toward the outer circumferential surface; and a second region which is continuous to the first region and in which the space becomes wider toward the rotation axis. In a cross section perpendicular to the rotation axis, the rake face includes a return face continuous to the outer circumferential surface, the return face being recessed opposite to a rotation direction of the drill. When a first boundary represents a boundary between the outer circumferential surface and the first region and a second boundary represents a boundary between the first region and the second region, a length of the first boundary is larger than a length of the second boundary in a direction parallel to the rotation axis. The second boundary is continuous to the return face.

Abstract: The holder has a first surface and a second surface. The head includes a cutting edge portion and a shank portion. The holder is provided with a first hole and a second hole communicating with the first hole, the first hole extending in a third direction inclined by a second angle relative to a second direction extending from the second surface toward the first surface when viewed in a direction parallel to the axis line. The shank portion has a flat surface portion, and is provided inside the second hole. The fastening portion is provided inside the first hole, and is in contact with the flat surface portion. In a plane perpendicular to the axis line, a third angle between the second direction and a fourth direction perpendicular to the flat surface portion is larger than the second angle. The third angle is less than 90°.

Abstract: Provided is a drill having a flat-shaped drill tip and excellent in cutting edge strength and chip removability. The drill includes: a cutting edge extending in a direction at an angle ? of not less than 85° and not more than 90° with respect to a drill axis (line O-O); a flank face contiguous to the cutting edge and having a clearance angle ? of not less than 5° and not more than 10° with respect to the drill axis (line O-O); and a rake face located opposite to the flank face across the cutting edge, the cutting edge includes a recess receding in a direction parallel to the drill axis (line O-O), and the rake face includes a front clearance formed at a side of an outer periphery of the drill.

Abstract: In a drill, a negative land is provided on a rake face, and a ridge line at an intersecting position of the negative land and a flank face, a ridge line at an intersecting position of the flank face and a margin, and a ridge line at an intersecting position of the negative land and the margin are convex faces in a longitudinal rectangular cross section. When a curvature radius of the convex face of a first ridge line at the intersecting position of the flank face and the negative land is 1, at curvature radius of the convex face of a second ridge line at the intersecting position of the flank face and the margin is 0.8 to 1.5 times the curvature radius of the first ridge line, and a curvature radius of the convex face of a fourth ridge line at the intersecting position of the negative land and the margin is 1.5 to 3.0 times the curvature radius of the first ridge line.

Abstract: In a drill, a negative hind is provided on a rake face, and a ridge line at an intersecting position of the negative land and a flank face, a ridge line at an intersecting position of the flank face and a margin, and a ridge line at an intersecting position of the negative land and the margin are convex faces in a longitudinal rectangular cross section. When a curvature radius of the convex face of a first ridge line at the intersecting position of the flank face and the negative land is 1, at curvature radius of the convex face of a second ridge line at the intersecting position of the flank face and the margin is 0.8 to 1.5 times the curvature radius of the first ridge line, and a curvature radius of the convex face of a fourth ridge line at the intersecting position of the negative land and the margin is 1.5 to 3.0 times the curvature radius of the first ridge line.

Abstract: Provided is a drill having a flat-shaped drill tip and excellent in cutting edge strength and chip removability. The drill includes: a cutting edge extending in a direction at an angle ? of not less than 85° and not more than 90° with respect to a drill axis (line O-O); a flank face contiguous to the cutting edge and having a clearance angle ? of not less than 5° and not more than 10° with respect to the drill axis (line O-O); and a rake face located opposite to the flank face across the cutting edge, the cutting edge includes a recess receding in a direction parallel to the drill axis (line O-O), and the rake face includes a front clearance formed at a side of an outer periphery of the drill.

Abstract: A small-diameter drill having a diameter of ?3 mm or less and an end that has undergone cross thinning is provided such that in a front view, a flute portion cutting edge is curved in concave with a degree of concavity with respect to an imaginary straight line in a range of 0.5 to 2% of a drill diameter, the imaginary straight line connecting the radially outer end of the flute portion cutting edge and the radially outer end of thinning portion cutting edge, the ratio of length of the thinning portion cutting edge to length of the flute portion cutting edge is set to 0.6 to 0.9:1, and in an axially perpendicular cross-sectional view, curvature radius of a heel-side flute surface of the flute is set to be smaller than curvature radius of a flute surface along the flute portion cutting edge.

Abstract: A small-diameter drill having a diameter of ?3 mm or less and an end that has undergone cross thinning is provided such that in a front view, a flute portion cutting edge is curved in concave with a degree of concavity with respect to an imaginary straight line in a range of 0.5 to 2% of a drill diameter, the imaginary straight line connecting the radially outer end of the flute portion cutting edge and the radially outer end of thinning portion cutting edge, the ratio of length of the thinning portion cutting edge to length of the flute portion cutting edge is set to 0.6 to 0.9:1, and in an axially perpendicular cross-sectional view, curvature radius of a heel-side flute surface of the flute is set to be smaller than curvature radius of a flute surface along the flute portion cutting edge.

Abstract: The problem of making it possible to shorten as much as possible the distance from a major margin to a minor margin of a two-edge double margin drill in an axial direction is addressed. An interval between major margins and respective minor margins, which are provided at outer peripheries of lands, are set at 80° to 100°, flank faces both include a flat second flank face and a flat third flank face, web thinning portions including web thinning surfaces having convex arcs in a direction of drill rotation in front view of the drill are formed at a central portion of an end, and an outer end of each web thinning surface in a radial direction is disposed behind an end of the corresponding minor margin in the direction of drill rotation and extends to the outer periphery of the corresponding land.

Abstract: An indexable insert for a drill includes a chip breaker for disposing chips, provided at an upper face thereof along a cutting edge. The chip breaker has at least one recess. The recess is retracted from an end of the chip breaker near the cutting edge toward the center of the insert by 0.2 mm or greater, or an end of the recess near a center hole of the insert communicates with the center hole.

Abstract: A flute spread angle ? in a drill axis-perpendicular section of a spiral flute is defined, a region of the flute taking part in chip treatment is formed along a first circle along an cutting edge of a concave curve and a second circle inscribed in this circle, both of the first circle and the second circle are circumscribed on a third circle expressing the web thickness, the radius R of the first circle and the radius R1 of the second circle are in the range of 0.40 D to 0.70 D and in the range of 0.15 D to 0.30 D respectively, and a drill rotational direction front portion of the spiral flute is formed on the second circle to be closer to the drill center than a fourth circle having a diameter of 0.65 D.

Abstract: An indexable insert for a drill includes a chip breaker for disposing chips, provided at an upper face thereof along a cutting edge. The chip breaker has at least one recess. The recess is retracted from an end of the chip breaker near the cutting edge toward the center of the insert by 0.2 mm or greater, or an end of the recess near a center hole of the insert communicates with the center hole.

Abstract: A throwaway drill capable of machining a workpiece stably in a balanced manner even under high-efficiency, high-load conditions and capable of disposing of chips efficiently and smoothly. The drill carries an outer insert and an inner insert. As shown, each insert has a plurality of cutting edges each having a curved crest, a first slope, and a second slope which is at least partially a curved line. The inner and outer inserts are arranged so that the cutting area to be cut by the outer insert alone is partially cut by a cutting edge portion of the inner insert near its corner, and the cutting area which to be cut by the inner insert alone is partially cut by the crest of one cutting edge of the outer insert.

Abstract: A drill capable of drilling a deep hole while keeping high chip discharging ability and having a helical flute whose width and helix angle will not change even after the cutting edges have been regenerated by regrinding. The drill has a tip portion formed with a helical flute having a constant width and helix angle, a rear portion formed with a helical flute which are greater in width and smaller in helix angle than the helical flute formed in the tip portion, and a middle portion provided between the tip portion and rear portion and formed with a helical flute smoothly connecting with the helical flutes of the tip portion and rear portion and having a gradually increasing width and a gradually decreasing helix angle from the tip portion toward the rear portion.