A drill may include a main body having a bar shape extending from a first end to a second end. The main body may be rotatable around a rotation axis. The main body may include a cutting edge, a first flute extending from the cutting edge, and a second flute extending from the first flute. The first flute may include, in a cross section orthogonal to the rotation axis, a first portion having a concave curvilinear shape located at a rear side in a rotation direction, and a second portion having a convex curvilinear shape located at a front side in the rotation direction. The second flute has a concave curvilinear shape from an end portion located at a front side in the rotation direction to an end portion located at a rear side in the rotation direction in the cross section.

A drill may be extended from a first end to a second end and may include a cutting part. The cutting part may include a cutting edge, a flute, an end surface and a connection surface. The flute may be extended from the cutting edge toward the second end. The end surface may be located closer to the second end than the flute. The connection surface may be located between the flute and the end surface. The connection surface may include a first portion, and a second portion located closer to an outer periphery of the cutting part than the first portion. A length in the direction along the rotation axis on the second portion may be smaller than a length in the direction along the rotation axis on the first portion in a side view orthogonal to the rotation axis.

A main body (3) of a replaceable-tip cutting tool (1) includes a cylinder-shaped cylindrical portion (32) made from a first metal material and extending in an axial direction, and with a female thread portion (33) provided on an inner circumference (40) of the cylindrical portion (32) and capable of being screwed together with a male threaded portion (24) of a cutting head (2). The female thread portion (33) includes a first female thread portion (34) and a second female thread portion (35). The first female thread portion (34) is a portion between a top of a female thread crest (37) of the female thread portion (33) and a portion of the female thread portion (35) that is on the female thread crest (37) side of a female thread root (36) and on the female thread root side of a portion corresponding to an effective diameter of the female thread portion (33). The first female thread portion (34) is made from a second metal material that is different from the first metal material. The second female thread portion (35) is continuous with the inner circumference (40) of the cylindrical portion (32). The second female thread portion is a remaining portion of the female thread portion excluding the first female thread portion. The second female thread portion (35) is made from the first metal material.

A modular rotary cutting tool includes a cutting head for insertion into a support. The cutting head has a coupling pin having torque surfaces and clamping surfaces formed on its outer peripheral surface. The coupling pin is divided into a front pin part and a rear pin part. The front pin part is defined by a circumferential groove. Stop surfaces for an axial pullout prevention are formed between the front pin part and the rear pin part. The torque surfaces and the clamping surfaces are arranged in different pin parts. For example, the clamping surfaces are preferably formed on the front pin part and the torque surfaces are preferably formed on the rear pin part. The clamping surfaces taper radially inward in a direction of the front cutting part at an angle of inclination, 2, with respect to the axis of rotation. Other variants and embodiments are broadly contemplated herein.

A cutting tool may include a circular columnar body extending from a first end to a second end along a rotation axis. At least a part of the columnar body may correspond to an insert including a cutting edge at the first end. The insert may include therein a flow path extending from a side of the first end toward a side of the second end. A width of the flow path along a radial direction of the circular columnar body may be smaller than a width of the flow path along a circumferential direction of the circular columnar body in a cross section orthogonal to the rotation axis.

A rotary cutting tool includes a replaceable cutting insert, a pocket portion for holding the cutting insert, and a chip flute portion having a plurality of helical flutes. An internal coolant passage is formed in the chip flute portion and has both a twisted geometry and a see-through central portion. The internal coolant passage is polygonal in cross-sectional shape having a number of cusps equal to the number of flutes. The internal coolant passage greatly increases coolant flow area, while maintaining the stiffness and rigidity of the cutting tool. A method includes forming the internal coolant passage using additive manufacturing such that the internal coolant passage has a see-through central portion and a twisted geometry.

The holder has a first surface and a second surface. The head includes a cutting edge portion and a shank portion. The holder is provided with a first hole and a second hole communicating with the first hole, the first hole extending in a third direction inclined by a second angle relative to a second direction extending from the second surface toward the first surface when viewed in a direction parallel to the axis line. The shank portion has a flat surface portion, and is provided inside the second hole. The fastening portion is provided inside the first hole, and is in contact with the flat surface portion. In a plane perpendicular to the axis line, a third angle between the second direction and a fourth direction perpendicular to the flat surface portion is larger than the second angle. The third angle is less than 90.

A drill tip may include a first part and a second part. The first part includes a cutting edge located at a side of a first end, and a recess located at a side of a second end, where the first end is one side of a central axis and the second end is another side of the central axis. The second part includes a shank portion extending along the central axis, and an engaging portion which connects to the shank portion at a side of the first end and includes a diameter greater than the shank portion. The engaging portion is located in the recess.

A rotatable cutting tool, which extends along a tool axis defining an axial direction, includes a cutting formation in a first axial longitudinal end region, which is configured for material ablation on a workpiece, and includes a screw-connection formation in a second axial longitudinal end region opposing the first, which is configured for screw connection with a coupling unit. The cutting tool includes key-contact surface formations diametrically opposing each other with respect to the tool axis, which are configured for torque-transmitting abutting engagement with key surfaces of a key. Each of the key-contact-surface formations includes at least two key-contact surface regions provided with spacing from each other in the circumferential direction about the tool axis, which key-contact surface regions are inclined away from each other such that they form a vertex projecting away from the tool axis.

A drill bit has a cutting portion having an annular portion, where the annular portion has a first end on which is disposed a cutting element and a second end that includes an outer insertion element and a stop shoulder. The drill bit has a drill shaft portion having a cylindrical drill shaft, where the drill shaft has an inner insertion element with an end face on a side of the drill shaft facing the cutting portion. The outer insertion element and the inner insertion element together form a plug connection in an insertion direction that is parallel to the axis of rotation and the insertion elements are connectable to each other via a pin element that is movable into a slot-shaped recess. The pin element is attached to an outside of the inner insertion element and the outer insertion element has the slot-shaped recess.