A method and apparatus for forming a pressure vessel liner are disclosed. One method includes forming an extruded tube by extruding a parison through a die and a mandrel and forming main body sections and return line sections in the extruded tube according to a first pattern. A cross-sectional area of the return line sections is smaller than a cross-sectional area of the main body sections. The method further includes changing the pattern according to which the main body sections and the return line sections are formed from the first pattern to a second pattern without stopping the forming of the extruded tube and forming the main body sections and the return line sections in the extruded tube according to the second pattern.

The present invention provides a corrugated tube and a method for manufacturing the same capable of improving workability in press-fitting work of a pipe or a quick connector. A corrugated tube includes a flexible section having a first corrugated section and a second corrugated section, and straight sections integrally formed at both ends of the flexible section respectively. A length of valley portions in an axial center direction is larger than a length of valley portions in the first corrugated section, thereby allows a pitch P2 of mountain portions in the second corrugated section provided between the straight section and the first corrugated section to be larger than a pitch P1 of mountain portions in the first corrugated section.

The present invention provides a corrugated tube and a method for manufacturing the same capable of improving workability in press-fitting work of a pipe or a quick connector. A corrugated tube includes a flexible section having a first corrugated section and a second corrugated section, and straight sections integrally formed at both ends of the flexible section respectively. A length of valley portions in an axial center direction is larger than a length of valley portions in the first corrugated section, thereby allows a pitch P2 of mountain portions in the second corrugated section provided between the straight section and the first corrugated section to be larger than a pitch P1 of mountain portions in the first corrugated section.

A method and apparatus for forming a pressure vessel liner are disclosed. One method includes forming an extruded tube by extruding a parison through a die and a mandrel and forming main body sections and return line sections in the extruded tube according to a first pattern. A cross-sectional area of the return line sections is smaller than a cross-sectional area of the main body sections. The method further includes changing the pattern according to which the main body sections and the return line sections are formed from the first pattern to a second pattern without stopping the forming of the extruded tube and forming the main body sections and the return line sections in the extruded tube according to the second pattern.

A method and apparatus for forming a pressure vessel liner are disclosed. One method includes forming an extruded tube by extruding a parison through a die and a mandrel and forming main body sections and return line sections in the extruded tube according to a first pattern. A cross-sectional area of the return line sections is smaller than a cross-sectional area of the main body sections. The method further includes changing the pattern according to which the main body sections and the return line sections are formed from the first pattern to a second pattern without stopping the forming of the extruded tube and forming the main body sections and the return line sections in the extruded tube according to the second pattern.

A flexible hose including a first tubular element of corrugated shape having in longitudinal cross-section a series of outer crests and a second tubular element of lightweight polymeric material externally associated with said first tubular element so as to fill at least partially a corresponding series of troughs alternately shaped by said outer crests.

A flexible hose including a first tubular element of corrugated shape having in longitudinal cross-section a series of outer crests and a second tubular element of lightweight polymeric material externally associated with said first tubular element so as to fill at least partially a corresponding series of troughs alternately shaped by said outer crests.

A pulsating corrugator is provided with at least one secondary mold block that is selectively used for forming a spigot connection as the corrugated or ribbed pipe is formed. Preferably, the primary mold blocks used to form the corrugated pipe are also used to assist in further cooling of the formed spigot connection once released from the secondary mold block. The corrugator also includes a controller used to provide different air pressure as the mold blocks move past extrusion outlets of an associate extruder.

A pulsating corrugator is provided with at least one secondary mold block that is selectively used for forming a spigot connection as the corrugated or ribbed pipe is formed. Preferably, the primary mold blocks used to form the corrugated pipe are also used to assist in further cooling of the formed spigot connection once released from the secondary mold block. The corrugator also includes a controller used to provide different air pressure as the mold blocks move past extrusion outlets of an associate extruder.

A method of forming a component having grooves formed into an outer surface of a component includes the steps of applying at least one mold to an outer surface of a component preform. The mold is forced into contact with the outer surface to form a detent into the outer surface.