A metal cutting drill insert for a drill tool having a chip disruptor provided at a rake face. The chip disruptor is further configured with a chamfer at a leading cutting edge region to increase cutting resistance and facilitate chip breakage.

A rotary tool may include a body, the body may include a cutting edge and a first groove. The first groove may include a first region having a first helix angle, a second region having a second helix angle, a third region having a third helix angle, a fourth region having a fourth helix angle, and a fifth region having a fifth helix angle. The fourth helix angle and the fifth helix angle may each decrease from a side of a first end toward a second end. A decreasing range of a value of the fourth helix angle of the fourth region may be less than a decreasing range of a value of the fifth helix angle of the fifth region. A length of the fourth region may be greater than a length of the fifth region.

A drilling tool includes at least two chip flutes and a chisel edge with a thinned region. The thinned region merges continuously into the chip flutes in such a way that the thinned region forms the end of the respective chip flute in the region of the chisel edge.

A drill structure comprises a shank part and a bit part. A web is formed on the front end of the bit part. Two sides of the web are tilted backward to form two cutting faces. At least one chip-discharge groove is formed on the surface of the bit part. Each cutting face includes a primary cutting face and a secondary cutting face. The thickness of the prismatic web edge of at least one primary cutting face is smaller than the outer-side width of the primary cutting face. An auxiliary cutting face is extended to the wall of the flute from the cutting edge of the primary cutting face and a portion of a blade back of the secondary cutting face of another cutting face. The present invention decreases the drilling resistance during drilling a hole and increases the service life of the drill bit.

A drill includes a tip cutting edge provided at a tip end thereof and a main cutting edge continuous to a rearward of the tip cutting edge. A point angle of the tip cutting edge is a predetermined acute angle. A point angle of the main cutting edge decreases from a front end toward a rear end of the main cutting edge. A point angle at the front end of the main cutting edge is an acute angle greater than the point angle of the tip cutting edge.

A metal drilling tool comprising includes a middle axis, a front side and an opposite end, with at least two cutting edges arranged in a region of the front side, a first free surface being associated with each cutting edge. The at least two cutting edges lie on an imaginary first conical surface arranged concentrically in relation to the middle axis, with a first conical angle that opens up towards the opposite end and reaches a maximum of 180. A centering section includes at least three edges, at least three side surfaces and an imaginary base surface. At least two of the edges lie on an imaginary second conical surface which is arranged concentrically in relation to the middle axis and has a second conical angle that opens up towards the opposite end. The second conical angle is smaller than the first conical angle, such that the imaginary second conical surface, seen from the opposite end, projects opposite the front surface.

A drill according to an embodiment includes a bar-shaped drill body extending along a rotation axis, a cutting edge located at a front end of the drill body, and a first flute extending spirally from the cutting edge toward a rear end of the drill body. The first flute includes a first region which is located close to the front end and has a helix angle 1, and a second region which is located closer to the rear end than the first region and has a helix angle 2 smaller than the helix angle 1. The second region includes an elongated protruding part along the first flute.

The drill comprises a base body, which extends in the axial direction along an axis of rotation and rotates about the axis of rotation in a direction of rotation during operation. Into the base body are incorporated flutes and between consecutive flutes is formed a rear surface, which extends, in relation to the direction of rotation, from a leading flute to a trailing flute. On the rear surface in the region of the leading flute, a guide chamfer and a support chamfer spaced apart from it in the direction opposite the direction of rotation are formed, wherein the support chamfer, as radially outermost region, forms a support edge for a merely linear support.

The present invention is concerned with twist drills for drilling of composite materials such as carbon fibre reinforced plastic (CFRP) and glass fibre reinforced plastic (GFRP). The present invention proposes that a twist drill (2) is provided with a variable helix having a defined start and finish helix angle, in combination with primary and secondary relief angles such that the drill (2) is adapted to minimise thrust force, particularly when used for drilling fibre-containing composite materials and especially for hand drilling. Start and finish helix angles of 50 and 10; 50 and 30; and 30 and 10 have been shown to provide excellent cutting performance and exit hole quality. A large secondary chisel edge angle (24) has also been found to contribute to excellent performance with composite materials, including stack machining.

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.