An interlocking thread with a tooth-cross-section that is wider at its crest than at its root and with V angles located both along the crest and the root which tightens into a tapped hole that has a similar thread cross-section.

An interlocking thread with a tooth-cross-section that is wider at its crest than at its root and with V angles located both along the crest and the root which tightens into a tapped hole that has a similar thread cross-section.

An access device is provided for access to a fluid tank, especially a fluid tank of a ship. The access device includes a drill, a thread-forming unit, a hollow body with an external thread and a connection plate. The hollow body is provided with a valve.

An access device is provided for access to a fluid tank, especially a fluid tank of a ship. The access device includes a drill, a thread-forming unit, a hollow body with an external thread and a connection plate. The hollow body is provided with a valve.

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 method of machining a screw is provided that is capable of preventing formation of a protruding section at a thread tip section. A thread is formed by cutting on a cylindrical body, and a surface of the thread is plastically deformed by rolling. Because of the cutting, a width between-side surfaces of a thread tip section is in a narrowed state as compared to a normal width. This width is narrowed toward a tip of the thread while a thread body section has a width expanded as compared to a normal width. Consequently, the side surfaces are formed to bulge by an excess thickness portion as compared to normal side surfaces. The rolling plastically deforms both side surfaces to cause the excess thickness portion to plastically flow toward the side surfaces.

A method of machining a screw is provided that is capable of preventing formation of a protruding section at a thread tip section. A thread is formed by cutting on a cylindrical body, and a surface of the thread is plastically deformed by rolling. Because of the cutting, a width between-side surfaces of a thread tip section is in a narrowed state as compared to a normal width. This width is narrowed toward a tip of the thread while a thread body section has a width expanded as compared to a normal width. Consequently, the side surfaces are formed to bulge by an excess thickness portion as compared to normal side surfaces. The rolling plastically deforms both side surfaces to cause the excess thickness portion to plastically flow toward the side surfaces.

An interlocking thread with a tooth-cross-section that is wider at its crest than at its root and with V angles located both along the crest and the root which tightens into a tapped hole that has a similar thread cross-section.

An interlocking thread with a tooth-cross-section that is wider at its crest than at its root and with V angles located both along the crest and the root which tightens into a tapped hole that has a similar thread cross-section.

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.