Disclosed are a drill and an insert for a drill having improved centering capability and cutting performance. In the drill of the present disclosure, central relief surfaces of cutting parts are processed as flat relief surfaces, and outer circumferential relief surfaces continuing from the center part to the outer circumferential surface of the drill are processed as curved relief surfaces, thereby enhancing the centering capability of the drill and minimizing the generation of drill vibration and burrs. In addition, in the drill of the present disclosure, the outer relief surfaces of the drill in contact with a hole to be drilled are processed such that an angle between the tangential lines of the outer relief surfaces is constant regardless of the size of the outer diameter of the drill, thereby achieving consistent performance of the drill despite change in the outer diameter of the drill.

A cutting element may include a substrate having a non-planar upper surface with a peripheral edge, and an ultrahard layer. The upper surface may include at least one depression formed at least proximate the peripheral edge; and a compressive stress hoop extending around the upper surface adjacent the peripheral edge, extending into the at least one depression, and configured to reduce tensile stress in the ultrahard layer. The ultrahard layer may be on the substrate and may have a non-planar top surface and an interface formed between the ultrahard layer and the substrate.

In this drill, a wall face of a chip removal groove includes a first wall face having a concave curve shape and a second wall face having a straight line shape in a cross section orthogonal to an axis of the drill main body, an extension line of a straight line of the second wall face extends in a direction opposite to a drill rotation direction as the straight line of the second wall face goes to an outer periphery side of the drill main body with respect to a radius line connecting an outer peripheral end of the second wall face and the axis with each other, the cutting edge includes a first cutting edge having a concave curve shape and a second cutting edge having a straight line shape which intersects with the first cutting edge at an obtuse angle.

Provided is a method for manufacturing a sintered component, which can suppress occurrence of edge chipping when a through-hole is formed in a powder-compact green body and also has a good productivity. The method for manufacturing a sintered component includes a molding step of press-molding a raw material powder containing a metal powder and thus fabricating a powder-compact green body; a drilling step of forming a hole in the powder-compact green body using a drill; a sintering step of sintering the powder-compact green body after drilling, wherein the drill used for drilling has a circular-arc shaped cutting edge on a point portion thereof.

The invention relates to a conical countersink (10) having at least one main cutting edge (16-1, 16-2, 16-3) extending in an arc-shaped, in particular spiral-shaped manner.

A cutting tool has a rake face and a flank face. The flank face is provided with a coolant supply hole. A ridgeline between the rake face and the flank face forms a cutting edge. An outer shape of the coolant supply hole in a cross section orthogonal to an axis includes a first portion facing the cutting edge, and a second portion opposite to the cutting edge when viewed from the first portion. The first portion has a concave portion extending toward the second portion. The concave portion is defined by a first side portion and a second side portion facing each other, and a bottom continuous with both the first side portion and the second side portion. In the cross section, an angle formed by a tangent of the first side portion and a tangent of the second side portion is not more than 160°.

An insert includes a main body extending from a first end toward a second end. The main body includes a cutting edge, a rake face, and a flute. In the rake face, a second rake angle of a second surface region positioned closer to the second end than a first surface region connected to the cutting edge is smaller than a first rake angle of the first surface region. A third rake angle of a third surface region is smaller than the second rake angle, the third surface region being adjacent to the flute rearward in a rotational direction and on an outer peripheral side of the main body.

Drill for drilling in hard materials, including a drill head having a rotational axis, wherein the drill head includes an apex aligned with the rotational axis and centre point cutting edges radially extending and receding from the apex. A first one of the centre point cutting edges and a second one of the centre point cutting edges have a different radius and/or are receding at least for a part at a different rate. A drill for drilling in hard materials, including a drill head having a rotational axis. The drill head includes a centre point aligned with the rotational axis and main cutting edges radially extending from the centre point, wherein each of the main cutting edges deviates from a radial.

A drill includes a leading end portion. The leading end portion is flat and has at least two cutting blades extending from a rotation center toward outside in a radial direction. The each cutting blade includes an arc-shaped portion. An inside linear portion is formed in a linear shape and connects to one end of the arc-shaped portion on the rotation center side. An outside linear portion is formed in a linear shape and connects to another end of the arc-shaped portion on an opposite side to the one end. The arc-shaped portion has a cutting edge provided with an arc-shaped portion chamfered surface. The inside linear portion and the outside linear portion each has a cutting edge provided with a linear portion chamfered surface. A drill axis direction width of the arc-shaped portion chamfered surface is smaller than a drill axis direction width of the linear portion chamfered surface.

According to one implementation, a drill includes the first cutting edges, the second cutting edges and a deflection reducer. The first cutting edges drill a prepared hole to a workpiece. The first cutting edges are formed in a tip side of the drill. The first point angle and each first relief angle of the first cutting edges continuously or intermittently decrease from the tip side toward a rear end side of the drill. The second cutting edges ream the prepared hole. The second cutting edges are formed at positions away in the rear end side from the first cutting edges. The second cutting edges have the second relief angles at a maximum diameter position. The deflection reducer reduces deflection of the second cutting edges. The deflection reducer is formed between the first cutting edges and the second cutting edges. The deflection reducer is inserted into the prepared hole.