A thread forming tap includes a partial thread. The partial thread is provided, in the axis direction view, with a protrusion formed so as to protrude in the radial direction and a clearance section formed so as to have a smaller diameter than the protrusion, and as a result of the foregoing, if a thread forming tap rotates in a state where the inner circumferential surface of a pilot hole and the partial thread come into contact, the protrusion of the partial thread can be caused to engage with the inner circumferential surface of the pilot hole. Due to this configuration, rubbing in a state where the partial thread is pressed against the inner circumferential surface of the pilot hole can be suppressed, and as a result, chipping of the partial thread can be prevented.

A surface-coated cutting tool includes a substrate composed of cemented carbide and a coating film. The coating film includes an intermediate layer in contact with the substrate and an upper layer formed on the intermediate layer. The upper layer is made up of a single layer consisting of an upper base layer which is a layer in contact with the intermediate layer or multiple layers constituted of two or more layers. A mismatch in lattice interplanar spacing in an interface region between the substrate and the intermediate layer is not higher than 65% of a theoretical value of a mismatch in lattice interplanar spacing between the substrate and the upper base layer. A mismatch in lattice interplanar spacing in an interface region between the intermediate layer and the upper base layer is not higher than 65% of the theoretical value of the mismatch in lattice interplanar spacing between the substrate and the upper base layer.

A surface-coated cutting tool includes a substrate composed of cemented carbide and a coating film. The coating film includes an intermediate layer in contact with the substrate and an upper layer formed on the intermediate layer. The upper layer is made up of a single layer consisting of an upper base layer which is a layer in contact with the intermediate layer or multiple layers constituted of two or more layers. A mismatch in lattice interplanar spacing in an interface region between the substrate and the intermediate layer is not higher than 65% of a theoretical value of a mismatch in lattice interplanar spacing between the substrate and the upper base layer. A mismatch in lattice interplanar spacing in an interface region between the intermediate layer and the upper base layer is not higher than 65% of the theoretical value of the mismatch in lattice interplanar spacing between the substrate and the upper base layer.

A tool for the chipless production of a thread in a workpiece comprises at least one shaping region which can be rotated about a tool axis (A) for the chipless production or finishing of the thread. The shaping region comprises a plurality of pressing lobes projecting radially outwardly from the tool axis (A) for producing the thread by pressing the pressing lobes into the workpiece surface. The pressing lobes are successively arranged along a forming curve which substantially spirals around the tool axis (A), and the pitch of the forming curve essentially corresponds to the pitch of the thread to be produced or reworked. The forming curve has a helix angle (a), and a profile of at least one pressing lobe is designed in such a way that a thread produced in an axial section containing the tool axis is at least in sections round-arched or ogival.

A tool for the chipless production of a thread in a workpiece comprises at least one shaping region which can be rotated about a tool axis (A) for the chipless production or finishing of the thread. The shaping region comprises a plurality of pressing lobes projecting radially outwardly from the tool axis (A) for producing the thread by pressing the pressing lobes into the workpiece surface. The pressing lobes are successively arranged along a forming curve which substantially spirals around the tool axis (A), and the pitch of the forming curve essentially corresponds to the pitch of the thread to be produced or reworked. The forming curve has a helix angle (a), and a profile of at least one pressing lobe is designed in such a way that a thread produced in an axial section containing the tool axis is at least in sections round-arched or ogival.

The invention involves the extraction process of a glow plug pencil (23) or a broken pencil (23) which is stuck in a cylinder head (13) housing (11) of a glow plug engine comprising a lower (19) and upper (17) part, so that the upper part (17) forms a shoulder (21) with the lower part (19), the pencil (23) being stuck in the lower part (19). The process is remarkable in that it includes a step (a) for drilling a bore in the pencil (23) according to the longitudinal direction of the latter which is performed with the use of a drill bit (1) comprising a drilling part (5) with flutes (7) and a shank (3) respectively having a diameter smaller and greater than the lower part diameter (19) of the housing (11) so that the shank (3) forms a shoulder (9) with the drilling part (5), and in that step a) for drilling the bore includes the drilling of the pencil (23) until the said shoulder (9) of the drill bit (1) is positioned to a stop against the shoulder (21) of the housing (11).

A thread forming tool comprises a thread generating region that extends along a helical line with a thread pitch angle and a thread direction of the thread to be formed and has an active profile corresponding to the thread profile of the thread to be formed, wherein the thread generating region has a thread tooth having a thread profile with a front thread tooth profile flank and a rear thread tooth profile flank, has a front flank relieved surface, adjoining the front thread tooth profile flank and has a rear flank relieved surface, adjoining the rear thread tooth profile flank, wherein the front flank relieved surface is isolated relative to a front thread tooth flank envelope, wherein the rear flank relieved surface is displaced relative to a rear transverse plane wherein the helical line is inclined to the rear relative to the rear transverse plane by the thread pitch angle.

A thread forming tool comprises a thread generating region that extends along a helical line with a thread pitch angle and a thread direction of the thread to be formed and has an active profile corresponding to the thread profile of the thread to be formed, wherein the thread generating region has a thread tooth having a thread profile with a front thread tooth profile flank and a rear thread tooth profile flank, has a front flank relieved surface, adjoining the front thread tooth profile flank and has a rear flank relieved surface, adjoining the rear thread tooth profile flank, wherein the front flank relieved surface is isolated relative to a front thread tooth flank envelope, wherein the rear flank relieved surface is displaced relative to a rear transverse plane wherein the helical line is inclined to the rear relative to the rear transverse plane by the thread pitch angle.

The present invention provides a looseness-prevention screw thread structure including a screw thread having a predetermined pitch, a no-load flank which is an inclined surface in a direction in which the screw thread is advanced, and a load flank which is an inclined surface in a direction in which the screw thread is retracted, the no-load flank and the load flank being formed at both sides of the screw thread, in which the no-load flank of the screw thread includes: a first tangential portion which abuts against an arc portion formed at a thread crest of an opposing fastening object; and a second tangential portion which has a preset angle with respect to the first tangential portion and abuts against the arc portion.

A thread tap includes a shaft and teeth. The shaft includes helical passages from the threading end to the base end of the shaft. Each passage opens through an aperture in the threading end. A second tap includes a cap and the shaft includes an axially extending passage. The cap is coupled to the threading end and at least partially defines apertures in fluid communication with the passage and the exterior of the tap. A third tap includes teeth spaced apart by a plurality of linear flutes. The shaft includes a central passage and a plurality of flute passages. Each flute passage extends radially outward from a common location in the central passage to a corresponding one of the flutes. The central passage is closed to a terminal end of the threading end.