A twist drill having a shaft with a longitudinal axis, wherein the cutting tool includes a plurality of flutes extending about the longitudinal shaft along a helix angle and a plurality of lands adjacent the flutes. Each land has a cutting edge adjacent a corresponding flute and a margin (i.e. relief surface). A cutting point is adjacent a forward end of the shaft. A first, second and third forward cutting surfaces are adjacent the first, second and third cutting edges, respectively, and extend proximate the cutting point axially rearward for a predetermined length about the longitudinal axis of the shaft. The cutting edges are unequally angularly spaced from each other, and each forward cutting surface has a primary relief angle that are unequal to each other.

A drill bit includes a cutting head and a bit body. The cutting head has a tip and cutting parts. The bit body is connected to the cutting head and has a longitudinal axis extending through the tip. The bit body has chip discharge flutes. The cutting parts are disposed at different angular positions around the longitudinal axis. Each cutting part is concaved inwardly and bounds one of the chip discharge flutes. Each of the cutting parts includes a rake face that has a corner edge adjacent to a respective one of the chip discharge flutes. When a bottom of the cutting head is viewed in a direction parallel to the longitudinal axis of the bit body, the corner edge has an obtuse included angle.

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.

A blade section has two lands and two flutes in an alternating manner and also has a linear chisel edge. The lands are each provided with: a margin section that is continuous with a cutting blade; a clearance section that is continuous with the margin section and that has a smaller diameter than the margin section; and a pad that is continuous with the clearance section and that has the same width as the width of the margin section.

A cutting tool holder of the present disclosure includes a bar-shaped main body. The main body includes a first pocket to receive a first insert, a second pocket to receive a second insert, a first groove extending from the first pocket, and a second groove extending from the second pocket. The first groove includes a second opening located on a rear side in a rotation direction, and the second groove includes a fourth opening located on a rear side in the rotation direction in a cross section orthogonal to a rotation axis. An angle 1 formed by the second opening and an outer peripheral surface of the main body is smaller than an angle 2 formed by the fourth opening and the outer peripheral surface of the main body in a cross section orthogonal to the rotation axis.

The invention relates to a drill tip (2) comprising a base body (6) having chip flutes (22A,B) and extending in the axial direction along an axis of rotation (8) and having at least two main cutting edges (14A,B) on the front face thereof extending outward in the radial direction to a cutting corner (16A,B). Seen in cross section, the base body is asymmetric relative to rotation about the axis of rotation (8) at the height of the cutting corner (16A,B). The cross section of the base body is simultaneously designed having symmetrical spacing from the main cutting edges (14A,B). The drill tip (2) is in particular designed as an interchangeable modular part of a modularly designed drill tip (5). A drill base body (4) in which the drill tip (2) can be inserted can therefore in turn be designed symmetrically.

Provided is a cutting tool capable of improving both the biting property to a work material and the chip discharge property. The cutting tool includes a drill body rotated about a central axis, four or more cutting edges formed on one end portion of the drill body to face a forward side of a rotation direction, and a flute groove that is formed between the cutting edges adjacent to each other in a circumferential direction and extends substantially spirally along the central axis. (1) The one end portion includes a first tip portion that includes the central axis and has a first tip angle, and a second tip portion that extends from the first tip portion to an outer peripheral edge of the drill body and has a second tip angle larger than the first tip angle, and (2) the drill body includes a first core thickness portion that is formed in such a manner that a core thickness thereof gradually decreases from the one end portion to the other end portion, and a second core thickness portion that is formed in such a manner that a core thickness thereof is constant from the first core thickness portion toward the other end portion.

A cutting tool such as a drill (1) in which a coating layer (6) is provided to the surface of a base body (5) having a rod shape, which is equipped with a cutting edge (2) provided to at least the tip portion (A) of the base body (5) having a rod shape and a chip discharge section (4) provided adjacent to the cutting edge (2) so as to extend rearwards (i.e., towards the rear end) from the tip portion (A), the coating layer (6) comprising a mixture phase of diamond and graphite and having a diamond content ratio which is lower in a rear end located 10 mm rearward from the tip than in the tip portion (A).

A drilling tool for producing drill holes includes a tip and a shaft arranged opposite the tip in a direction of a longitudinal axis of the drilling tool. The drilling tool has at least one geometrically defined cutting edge in the tip area, and has an expanded diameter trailing the tip in a longitudinal direction from the tip. The drilling tool has a first area with a first diameter that precedes the expanded diameter, and a second area with a second diameter, larger than the first diameter, that trails the expanded diameter. The drilling tool is distinguished in that the expanded diameter and/or the second area is/are embodied such that chips are produced in the area of the expanded diameter and/or in the second area when a workpiece is machined, chips consistent with those produced when a workpiece is machined with a geometrically undefined cutting edge.

This HEMS (200) is provided with a control unit (230) that, if an operation directive does not go through a server (600) provided externally to a customer's home (10), identifies said operation directive as having come from within the customer's home, and if the operation directive does go through the server (600) provided externally to the customer's home (10), identifies the operation directive as having come from outside the customer's home.