A tap 1 has a threaded portion 2 including a cutting blade 5 on an outer circumferential surface, a flute portion 3 that divides the threaded portion 2 in a circumferential direction, and a shank portion 4 formed continuously from the threaded portion 2 and the flute portion 3 along a central axis O. The flute portion 3 includes, in a cross-sectional view, a first flute 31 formed continuously from the cutting blade 5 of the threaded portion 2, a second flute 32 formed continuously from the first flute 31, and a ridge line portion 33 being a boundary between the first and second flutes 31, 32. A distance e from the central axis O to the ridge line portion 33 is longer than a distance d1 and a distance d2, respectively.

A pipe-tapered-thread machining spiral tap includes a tapered thread portion that is circumferentially divided by flutes into a plurality of lands. Each of at least one of the lands has a cutting edge that extends along a corresponding one of the flutes. The flutes are made of a plurality of spiral flutes that are three, four or five spiral flutes each having a helix angle that is not smaller than 30 and smaller than 50. A flute width ratio AG/(AG+AL) is 0.3-0.5, where AG represents a central angle which is subtended by each of the flutes and which is defined at a center corresponding to the rotation axis in a cross section that is perpendicular to the rotation axis, and AL represents a central angle which is subtended by each of the lands and which is defined at the center in the cross section.

A fastener with improved threading for resisting multi-axial forces and off-axis loading scenarios is provided. The fastener may include a shaft and a plurality of helical threads disposed about the shaft. The plurality of helical threads may include a first helical thread and a second helical thread adjacent the first helical thread. The first helical thread may include a first concave undercut surface and a first convex undercut surface. The second helical thread may include a second concave undercut surface and a second convex undercut surface. When the fastener is viewed in section along a plane intersecting a longitudinal axis of the shaft, the first concave undercut surface and the second convex undercut surface may be oriented toward the proximal end of the shaft, and the first convex undercut surface and the second concave undercut surface may be oriented toward the distal end of the shaft.

A method of producing a nitrided cut tap that includes a nitrogen diffusion layer. The method includes (a) a nitriding step for forming the nitrogen diffusion layer in which nitrogen atoms contained in an atmospheric gas are diffused from a surface of a base material of the cut tap under heat, such that the nitrogen diffusion layer has a thickness ranging from 10 ?m to 30 ?m; and (b) a honing step for rounding a cutting edge portion by colliding abrasive particles against a local part of the cutting edge portion of the base material of the cut tap that has been subjected to the nitriding step, such that a difference between a thickness of the nitrogen diffusion layer in the cutting edge portion and a thickness of the nitrogen diffusion layer in flank and rake surfaces sandwiching the cutting edge portion, is not larger than 5 ?m.

A pipe-tapered-thread machining tap has a thread, four spiral flutes and four cutting edges that include a plurality of thread intersection portions at each of which a corresponding one of the four cutting edges intersects with the thread. The thread intersection portions of the cutting edges have four groups, such that each of the four groups has ones of the thread intersection portions that are portions of a corresponding one of the four cutting edges. Every two of the thread intersection portions of each of the four groups is removed, such that, in each of the four groups, at least one of the thread intersection portions that is removed and at least another one of the thread intersection portions that is not removed are alternately arranged in a direction in which a corresponding one of the four cutting edges extends.

A spiral flute tap includes a body having an axial forward end and an axial rearward end. The body has a cylindrical shank portion adjacent the axial rearward end, a threaded fluted portion adjacent the axial forward end, a non-threaded fluted portion between the cylindrical shank portion and the threaded fluted portion, and a central, longitudinal axis. The spiral flute tap further includes a plurality of helical flutes formed at a helix angle, HA, with respect to the central, longitudinal axis of the tap that continuously increases in magnitude in the threaded fluted portion. In other words, the lead of the plurality of helical flutes continuously decreases in magnitude in a rearward direction for a predetermined distance. In one example, the helix angle, HA, varies at a rate of between 0.5 degrees/mm to 4.0 degrees/mm. A method of making the spiral flute tap is also disclosed.

A pipe-tapered-thread machining spiral tap includes a tapered thread portion that is circumferentially divided by flutes into a plurality of lands. Each of at least one of the lands has a cutting edge that extends along a corresponding one of the flutes. The flutes are made of a plurality of spiral flutes that are three, four or five spiral flutes each having a helix angle that is not smaller than 30 and smaller than 50. A flute width ratio AG/(AG+AL) is 0.3-0.5, where AG represents a central angle which is subtended by each of the flutes and which is defined at a center corresponding to the rotation axis in a cross section that is perpendicular to the rotation axis, and AL represents a central angle which is subtended by each of the lands and which is defined at the center in the cross section.

The present disclosure provides a variable helical composite tap, which includes a drill bit segment and a tap segment sequentially arranged, where a helical angle of the drill bit segment is greater than a helical angle of the tap segment, and a core thickness of the tap segment is greater than a core thickness of the drill bit segment. The helical angle of the drill bit segment from a drill tip to a connection end of the tap segment with the drill bit segment increases continuously. The helical angle of the tap segment from the drill tip to a drill handle increases continuously, and preferably, the core thickness from the drill tip to the drill handle increases continuously. Compared with the prior arts, the drill bit segment of the present disclosure has a greater helical angle and a better chips removal effect is produced in the drill bit.

A process of forming a fastener with improved threading to resist multi-axial forces and off-axis loading scenarios is provided. The process may include placing first and second mill tools adjacent a shaft of the fastener having a proximal end and a distal end, rotating the shaft and the first and second mill tools, and translating the first and second mill tools along at least part of a length of the shaft to form: a first concave undercut surface oriented toward the proximal end, a first convex undercut surface oriented toward the distal end, a second concave undercut surface oriented toward the distal end, and a second convex undercut surface oriented toward the proximal end.

The present invention relates to a threading tool for producing a thread notch on a workpiece. The production may be both material-removing production and also chipless production. The threading tool comprises at least two regions, a distal machining region with a machining head, and a proximal shank region with a shank, which shank narrows toward the machining region via a shoulder. Furthermore, the threading tool according to the invention is designed such that at least one fluid duct extends through the shank, which at least one fluid duct opens out in the machining region.