A blow-molded plastic structure has a hollow interior portion formed during a blow-molding process, and includes first and second outer portions that are spaced apart from each other, with the hollow interior portion disposed there between. The structure includes a pattern of structural stiffening features that are integrally formed in the second outer portion. The pattern of structural stiffening features includes a plurality of tripodal depressions disposed in rows and columns and a plurality of convex regions disposed in rows and columns between the plurality of tripodal depressions. Each convex region has a maximum height between the first and second outer portions. Each of the tripodal depressions extends into the hollow interior portion, includes three indentations disposed adjacent the first outer portion, and includes an island spaced away from the first outer portion. The island has three sides, each of which is disposed adjacent one of the three indentations.

A blow-molded plastic structure has a hollow interior portion formed during a blow-molding process, and includes first and second outer portions that are spaced apart from each other, with the hollow interior portion disposed there between. The structure includes a pattern of structural stiffening features that are integrally formed in the second outer portion. The pattern of structural stiffening features includes a plurality of tripodal depressions disposed in rows and columns and a plurality of convex regions disposed in rows and columns between the plurality of tripodal depressions. Each convex region has a maximum height between the first and second outer portions. Each of the tripodal depressions extends into the hollow interior portion, includes three indentations disposed adjacent the first outer portion, and includes an island spaced away from the first outer portion. The island has three sides, each of which is disposed adjacent one of the three indentations.

A fuel tank includes: a tank main body made of a resin material; and a cover member which is formed using threads made of a fiber-reinforced composite material containing a thermoplastic resin fusible to a surface of the tank main body. The cover member has a twill weave structure at least in its portion fused to the upper surface of the tank main body. The threads each have a core-sheath structure in which a fiber made of a polypropylene resin is coated with a polyethylene resin.

A thermoplastic pre-container, typically a blow molded piece, is provided to form several hollow bodies. The pre-container is elongated along a central axis and includes a bottom section, an opened section and in-between at least one hollow body section. A plurality of circumferential grooves are provided in a pre-container sidewall, each with a bottom line formed in a virtual plane perpendicular to the axis. The bodies are obtained after cutting the pre-container in a direction transverse to the central axis and severing the end sections. Due to the cutting at several of the circumferential grooves, a top opening and a base opening are respectively obtained for at least two hollow bodies, each opening being delimited by an annular inner rim of a body flange.

This method for manufacturing a pipe (2) for a vehicle fuel tank involvesmolding a wall, comprising an inner layer (6) made from ethylene vinyl alcohol (EVOH) and an outer layer (8) made from a polymer suitable for welding, in a mold comprising at least one female shoulder that creates at least one male shoulder on an outer surface of an end portion of the wall during molding, thencutting off the end portion of the wall.

This method for manufacturing a pipe (2) for a vehicle fuel tank involvesmolding a wall, comprising an inner layer (6) made from ethylene vinyl alcohol (EVOH) and an outer layer (8) made from a polymer suitable for welding, in a mold comprising at least one female shoulder that creates at least one male shoulder on an outer surface of an end portion of the wall during molding, thencutting off the end portion of the wall.

A supporting assembly for a hollow tank body includes a supporting body (2) and supporting ends (1) provided at two ends of the supporting body. The supporting ends are provided with stepped transition assemblies (4) connected to the supporting body. The supporting body is configured with a hollow structure. The supporting body includes a supporting main body (5) and a base (6). The supporting main body is configured with a cylindrical structure or a cylindrical structure with a corrugated structure in the middle. With this structure, the deformation of the hollow tank body under the relatively high overpressure and the low negative pressure can be avoided, and the shape stability of the whole product can be enhanced. Meanwhile, the supporting structure needs less material, and has a light weight and lowered cost.

A supporting assembly for a hollow tank body includes a supporting body (2) and supporting ends (1) provided at two ends of the supporting body. The supporting ends are provided with stepped transition assemblies (4) connected to the supporting body. The supporting body is configured with a hollow structure. The supporting body includes a supporting main body (5) and a base (6). The supporting main body is configured with a cylindrical structure or a cylindrical structure with a corrugated structure in the middle. With this structure, the deformation of the hollow tank body under the relatively high overpressure and the low negative pressure can be avoided, and the shape stability of the whole product can be enhanced. Meanwhile, the supporting structure needs less material, and has a light weight and lowered cost.

A method of forming a headrest assembly includes providing a first mold that encloses a first cavity in a closed condition. A support is positioned in the first cavity. A first material is blow molded into the first cavity and around a portion of the support to form a core part. The core part and support are removed from the first mold. A second mold encloses a second cavity in a closed condition. The core part and the support are placed into the second mold in an open condition. A fluid is injected into the core part through the support. The second mold is converted to the closed condition. A second material is injection molded into the second cavity and around the core part to form an outer shell around the core part. A fluid is withdrawn from the core part through the support.

A method of forming a headrest assembly includes providing a first mold that encloses a first cavity in a closed condition. A support is positioned in the first cavity. A first material is blow molded into the first cavity and around a portion of the support to form a core part. The core part and support are removed from the first mold. A second mold encloses a second cavity in a closed condition. The core part and the support are placed into the second mold in an open condition. A fluid is injected into the core part through the support. The second mold is converted to the closed condition. A second material is injection molded into the second cavity and around the core part to form an outer shell around the core part. A fluid is withdrawn from the core part through the support.