An insert tool, in particular a drilling tool, having a base module is disclosed. The base module has a first portion, which in particular includes a conveying helix, and a second portion, which includes cutting bodies with preferably at least two rake faces. The second portion is connected to a first end of the first portion in an integrally bonded manner. The base module is connected, at a second end, to an, in particular hardened, insertion end in an integrally bonded manner by way of in particular a friction welding method.

A drill head is rotated about a center axis. The drill head includes: a mounting surface that is an end face in a direction of the center axis; a tip surface that is an opposite surface to the mounting surface in the direction of the center axis; an outer peripheral surface continuous to the mounting surface and the tip surface; a cutting edge extending from the outer peripheral surface toward the center axis in the tip surface; a flute that is formed on the outer peripheral surface and extends spirally around the center axis from the tip surface to the mounting surface; and a thinning surface continuous to the tip surface and the flute. The tip surface includes: a first flank surface continuous to the cutting edge; and a second flank surface located on a side opposite to the first flank surface with the flute interposed therebetween.

In an embodiment, a drill has an elongated shape and a rotation axis. The drill includes a drilling portion, a shank portion, and a tapered portion. The shank portion includes a first helical flute and a first cutting edge. The tapered portion is located between the drilling portion and the shank portion. The tapered portion includes a second helical flute, a second cutting edge, a chamfered part, and a connection part. The chamfered part is getting smaller gradually as moving toward the first end side. The connection part has a curved surface and connects the second cutting edge and the drilling portion. A ratio of w/L is 0.0015-0.5 where L is a length of the second cutting edge in a front view of the first end, and w is a width of an outer peripheral end of the chamfered part in a direction parallel to the rotation axis.

A micro-reinforced concentric twist drill. Concentric drilling and micro-reinforcing technologies are applied to cutting faces of the twist drill, and upright micro-reinforced center drills are symmetrically arranged on spiral cutting surfaces on two sides of an axial central area, and extend to the rear cutting surface and form drill center hole cutters in a protruding manner; a micro-reinforced central cutting face is arranged on the inner side of each micro-reinforced center drill in a protruding manner, and the micro-reinforced central cutting face extends to the axial front and intersects with the rear cutting surface to form a micro-reinforced central drilling edge of the micro-reinforced concentric twist drill; and/or upright micro-reinforced reamers are symmetrically arranged on central areas of the spiral cutting surfaces on two sides of the axial center in an integral manner; a protruding reaming cutting face is formed on the inner side of each micro-reinforced reamer.

In an embodiment, a drill has an elongated shape and a rotation axis. The drill includes a drilling portion, a shank portion, and a tapered portion. The shank portion includes a first helical flute and a first cutting edge. The tapered portion is located between the drilling portion and the shank portion. The tapered portion includes a second helical flute, a second cutting edge, a chamfered part, and a connection part. The chamfered part is getting smaller gradually as moving toward the first end side. The connection part has a curved surface and connects the second cutting edge and the drilling portion. A ratio of w/L is 0.0015-0.5 where L is a length of the second cutting edge in a front view of the first end, and w is a width of an outer peripheral end of the chamfered part in a direction parallel to the rotation axis.

In the drill, each of the thinning edges extends beyond an intersection point with the chisel; an axial rake angle is in a range of +5 to +15; and a ratio of a length of each of the thinning edges to a length of each of the cutting edges in a direction, in which the main cutting edge extends as viewed from the front side of the axial direction, is in a range of 20% to 50%. Intersecting ridges between: second thinning wall surfaces facing an opposite side of the drill rotation direction; and the tip flank faces, are disposed that: they are spaced apart in a direction orthogonal to the intersecting ridges; they are positioned on one diameter line passing the axis; or they mutually pass over in a passing over amount of 0.03D or less with respect to a diameter of the cutting edges.