Abstract: A high-pressure fuel injection pipe of doubled type, comprising: a thick outer tube; and an inner tube of made a metal and fitted in the outer tube to form a doubled pipe which is formed at its end portion with a connecting head having a face to be fitted on a seat of a mating partner. The outer tube is made of stainless steel or titanium, and the inner tube is formed of a thin metal having a high corrosion-resistance and a high strength and is doubled on the inner circumference of the outer tube throughout its entire length.

Abstract: A structurally simple common rail is highly sealed and light weight manner. The common rail includes a thick wall pipe having a flow passage for accumulating pressure of high pressure fuel. The high pressure fuel is supplied from a high-pressure pump and distributed to an injection nozzle. The end portion of the thick wall pipe is reduced in diameter by drawing. A thread portion is formed on an outer peripheral surface of the diameter-reduced end portion. A connecting end of a piping component is connected to the end portion of the thick wall pipe by screwing a nut to the thread portion of the thick wall pipe.

Abstract: A common rail is provided which is simple in structure and capable of connecting a piping component to a thick wall pipe thereof in a highly sealed and light weighted manner. In a common rail adapted to connect a pipe component to at least one end of a thick wall pipe having a flow passage 1' therein for accumulating pressure of high pressure fuel so that high pressure fuel is supplied from a high-pressure pump and distribute-supplied to an injection nozzle, the end portion of the thick wall pipe 1 is reduced in diameter by drawing. A thread portion 1a is formed in an outer peripheral surface of the diameter-reduced end portion. A connecting end of the piping component 3 is connected to an end portion of the thick wall pipe 1 by screwing a fastening screw means 5, 5' to the thread portion 1a.

Abstract: Herein disclosed is a high-pressure fuel injection tube structure comprising: an injection tube body having a joint head at its one end; and a cap collar having a through hole generally at its center and such a sectional shape as to cover the joint head of the injection tube and made of a highly strong and corrosion-resistant metal material. Also disclosed is a method of manufacturing the high-pressure fuel injection tube structure. The cap collar is formed at the circumferential edge of the through hole thereof with a raised pawl wall retained on the circumferential of the communication hole of the injection tube body. The cap collar is formed with an inward flange at the end of its outer circumference. The highly corrosion-resistant metal material is one selected from the group consisting of stainless steel, inconel, hastelloy and titanium. The injection tube body has a double tube structure composed of a thicker outer tube member of steel and a thinner inner tube member of stainless steel or inconel.

Abstract: A method of manufacturing a thick-walled small diameter pipe by repeating a process comprising a pipe extension process and a heating process on a pipe to be processed plural times, wherein a machining process on the inner circumferential surface of said pipe to be processed is performed prior to the pipe extension process in the final cycle of said process or a process near the final cycle to remove a black skin layer, cracks and puckers, providing smooth inner surface and excellent proof pressure.

Abstract: A device for cutting the inner circumferential surface of a thick-walled small diameter pipe comprising a setting means for inserting a core bar having a cutting blade on one end thereof into a pipe to be processed, a rotating means for rotating said pipe to be processed set by the setting means about the axis thereof relative to said core bar, a feed means for cutting the inner surface of said pipe to be processed with said cutting blade while pulling the core bar which is securedly held at the other end thereof relative to said pipe to be processed, and a control means for controlling each of said means, providing a smooth high quality inner surface having excellent proof pressure against internal pressure.