Abstract: A drill has a thinning rake face formed in the front end. An intersection ridgeline between the thinning rake face and the tip flank face is the thinning edge. On the opposite side of the rotation direction, the first and second thinning wall surfaces (6b, 6c) and are formed. Viewed from the front, an intersection angle between the thinning edge (4a) and the first thinning ridgeline is larger than 95°. The second thinning ridgeline (L2) is bent to the opposite side of the rotation direction. The thinning edge and the first thinning ridgeline are connected via a concave curve line. The first and second thinning wall surfaces are connected via a concave surface, and a curvature radius of the concave curve line is smaller than a curvature radius of the concave surface.

Abstract: A drill has a thinning rake face formed in the front end. An intersection ridgeline between the thinning rake face and the tip flank face is the thinning edge. On the opposite side of the rotation direction, the first and second thinning wall surfaces (6b, 6c) and are formed. Viewed from the front, an intersection angle between the thinning edge (4a) and the first thinning ridgeline is larger than 95°. The second thinning ridgeline (L2) is bent to the opposite side of the rotation direction. The thinning edge and the first thinning ridgeline are connected via a concave curve line. The first and second thinning wall surfaces are connected via a concave surface, and a curvature radius of the concave curve line is smaller than a curvature radius of the concave surface.

Abstract: A drill comprising: a drill main body; a chip discharge flute; and a tip cutting edge. The tip cutting edge includes: a first tip cutting edge which extends toward the axially posterior end as it goes toward the outside in a radial direction; and a second tip cutting edge which is disposed outside the first tip cutting edge in the radial direction. The second tip cutting edge extends toward the tip in the axis direction as it goes toward the outside in the radial direction or extends to be perpendicular to the axis. The radially inner end of the second tip cutting edge is disposed on the axially posterior end with respect to the radially outer end of the first tip cutting edge. The radially outer end of the second tip cutting edge is disposed on a virtual extension line of the first tip cutting edge.

Abstract: A drill comprises a drill body that is rotatable on an axis. Chip evacuating flutes, which are open on front flanks of the drill body and are extended rearwards, are formed in a periphery of the drill body on its front side. Cutting edges are formed along ridge lines where the front flanks intersect with wall surfaces of the chip evacuating flutes facing a drill rotating direction. At least first and second front flanks are formed on the front flanks in order of their locations in the drill rotating direction from its leading side to its trailing side. A clearance angle of the second front flank is greater than that of the first front flank. Intersection lines of the first and second front flanks cross the cutting edges.

Abstract: A coolant-hole equipped drill includes a drill main body, a cutting edge portion which has a tip flank, a chip discharging groove provided with a front groove wall surface and a rear groove wall surface, a cutting edge formed at a ridge line portion where the front groove wall surface and the tip flank intersect with each other, a land portion formed between the chip discharging grooves adjacent to each other in the rotating direction, and a coolant hole drilled at the land portion and opened at the tip flank. The coolant hole includes a front hole wall surface, a rear hole wall surface, and an outer-circumference hole wall surface.

Abstract: A guide portion prevents the drilling hole from curving due to a skipping rope phenomenon, and also prevents the inner wall face of the drilling hole from being damaged, so that its surface roughness can be improved. Chip evacuating flutes 4 are formed in the periphery of a drill body 1 which has a stick shape and is rotatable on its axis O, from its front flank 3 toward the rear side. Cutting edges 2A are formed along ridge lines where the front flanks 3 intersect with wall faces 4A which are in the chip evacuating flutes 4 and face in a drill rotational direction T. A cutting edge section 2, where the cutting edges 2A are formed, is provided in the front side of the drill body 1. A cutting edge section 2 has an external diameter which is smaller toward the rear side in the axis O direction than the external diameter D at the cutting edges 2A. A guide portion 6 has a maximum external diameter part 6A at the front periphery side, and is provided to the rear side of the cutting edge section 2.

Abstract: A drill comprises a drill body that is rotatable on an axis. Chip evacuating flutes, which are open on front flanks of the drill body and are extended rearwards, are formed in a periphery of the drill body on its front side. Cutting edges are formed along ridge lines where the front flanks intersect with wall surfaces of the chip evacuating flutes facing a drill rotating direction. At least first and second front flanks are formed on the front flanks in order of their locations in the drill rotating direction from its leading side to its trailing side. A clearance angle of the second front flank is greater than that of the first front flank. Intersection lines of the first and second front flanks cross the cutting edges.

Abstract: A coolant-hole equipped drill includes a drill main body, a cutting edge portion which has a tip flank, a chip discharging groove provided with a front groove wall surface and a rear groove wall surface, a cutting edge formed at a ridge line portion where the front groove wall surface and the tip flank intersect with each other, a land portion formed between the chip discharging grooves adjacent to each other in the rotating direction, and a coolant hole drilled at the land portion and opened at the tip flank. The coolant hole includes a front hole wall surface, a rear hole wall surface, and an outer-circumference hole wall surface.

Abstract: A guide portion prevents the drilling hole from curving due to a skipping rope phenomenon, and also prevents the inner wall face of the drilling hole from being damaged, so that its surface roughness can be improved. Chip evacuating flutes 4 are formed in the periphery of a drill body 1 which has a stick shape and is rotatable on its axis O, from its front flank 3 toward the rear side. Cutting edges 2A are formed along ridge lines where the front flanks 3 intersect with wall faces 4A which are in the chip evacuating flutes 4 and face in a drill rotational direction T. A cutting edge section 2, where the cutting edges 2A are formed, is provided in the front side of the drill body 1. A cutting edge section 2 has an external diameter which is smaller toward the rear side in the axis O direction than the external diameter D at the cutting edges 2A. A guide portion 6 has a maximum external diameter part 6A at the front periphery side, and is provided to the rear side of the cutting edge section 2.

Abstract: A plurality of cutting oil feed holes extend from the proximal side towards the distal side are provided in a drill body located on a reference line that extends towards a circumferential central portion of an outer circumferential surface of the drill body split by a chip discharge groove from an axis in a cross section orthogonal to the axis. A cutting oil feed hole that is located on the radial outermost side is used as a first cutting oil feed hole, and a cutting oil feed hole that is on the radial innermost side is used as a second cutting oil feed hole. Two or more openings of the cutting oil feed holes are provided in one cutting edge as the plurality of cutting oil feed holes are formed in the vicinity of the intersection ridgeline portion between the distal flank face and the second thinned face.

Abstract: A plurality of cutting oil feed holes extend from the proximal side towards the distal side are provided in a drill body located on a reference line that extends towards a circumferential central portion of an outer circumferential surface of the drill body split by a chip discharge groove from an axis in a cross section orthogonal to the axis. A cutting oil feed hole that is located on the radial outermost side is used as a first cutting oil feed hole, and a cutting oil feed hole that is on the radial innermost side is used as a second cutting oil feed hole. Two or more openings of the cutting oil feed holes are provided in one cutting edge as the plurality of cutting oil feed holes are formed in the vicinity of the intersection ridgeline portion between the distal flank face and the second thinned face.

Abstract: In a drill in which a chip discharge groove twisted in the shape of a spiral relative to an axis is formed in the outer periphery of the tip section of a roughly cylindrical drill body that rotates around the axis, and a cutting edge is formed on the intersecting ridgeline between a wall surface facing in the direction of drill rotation of this chip discharge groove and a tip flank of the drill body, together with the section on the tip side of the chip discharge groove continuous with the cutting edge being a narrowed width section in which the helix angle relative to the axis and groove width are constant, a wide width section is formed in the chip discharge groove farther towards the rear end than this narrow width section, in which the helix angle is equal to the narrow width section and in which the groove width is widened relative to the narrow width section in the direction of drill rotation and towards the rear in the direction of drill rotation and has a constant width.

Abstract: The present invention provides a drill comprising: a drill main body rotatable about an axis of rotation, and having a tip end with a tip flank and a shank; a chip discharge flute formed on a periphery of the drill main body, and extending from the tip end toward the shank of the drill main body; and a cutting edge formed along an intersecting ridge where a wall surface of the chip discharge flute facing in the direction of drill rotation intersects the tip flank of the drill main body, wherein the cutting edge comprises a convex cutting edge toward the periphery and a concave cutting edge smoothly extending from the convex cutting edge.

Abstract: In a drill in which a chip discharge groove twisted in the shape of a spiral relative to an axis is formed in the outer periphery of the tip section of a roughly cylindrical drill body that rotates around the axis, and a cutting edge is formed on the intersecting ridgeline between a wall surface facing in the direction of drill rotation of this chip discharge groove and a tip flank of the drill body, together with the section on the tip side of the chip discharge groove continuous with the cutting edge being a narrowed width section in which the helix angle relative to the axis and groove width are constant, a wide width section is formed in the chip discharge groove farther towards the rear end than this narrow width section, in which the helix angle is equal to the narrow width section and in which the groove width is widened relative to the narrow width section in the direction of drill rotation and towards the rear in the direction of drill rotation and has a constant width.

Abstract: The present invention provides a drill comprising: a drill main body rotatable about an axis of rotation, and having a tip end with a tip flank and a shank; a chip discharge flute formed on a periphery of the drill main body, and extending from the tip end toward the shank of the drill main body; and a cutting edge formed along an intersecting ridge where a wall surface of the chip discharge flute facing in the direction of drill rotation intersects the tip flank of the drill main body, wherein the cutting edge comprises a convex cutting edge toward the periphery and a concave cutting edge smoothly extending from the convex cutting edge.

Abstract: The present invention provide for a cutting tool member that has been coated with a hard coating. The hard coating has multiple layers including: a) a layer made of a titanium compound that has a cubic lattice structure, b) an Al.sub.2 O.sub.3 layer, and c) an intervening layer that includes a Ti.sub.2 O.sub.3 compound with a corundum-type lattice structure. The hard coating layer provides the cutting tool member with good strength and increases its operational lifetime.