A method for producing a balloon from a suitable blank is provided. The blank is introduced into an outer mold heated an first expanded to expand it against the inner wall of the outer mold. Pressure is reduced to relax the blank away from the inner wall. The three-dimensional volume of the mold is changed. Second expanding of the blank expands again against the inner wall of the changed volume of the outer mold. Balloons of the invention consist of a middle cylindrical region and two end regions delimiting the middle cylindrical region. With a pressure application of 6 bar, a ratio of the cross section in the middle region to the cross section in the end region is at least 2, and preferably greater than 3.

A method of manufacturing fuel tanks made of polymer material using a blow molding technique, the method including: offering up at least one sheet form extrudate between two opposing cavities of an open mold with an impression that corresponds to a shape of a tank that is to manufactured; then bringing the two cavities together until the mold is closed; as the two cavities are being moved closer together and before the extrudate comes into contact with one of them, injecting a first fluid between the extrudate and at least one cavity; injecting a second fluid on the opposite side of the extrudate from each cavity, to press it firmly against the wall of the cavity; removing the first fluid present between the cavity and the extrudate before end of injection of the second fluid.

A method of manufacturing fuel tanks made of polymer material using a blow molding technique, the method including: offering up at least one sheet form extrudate between two opposing cavities of an open mold with an impression that corresponds to a shape of a tank that is to manufactured; then bringing the two cavities together until the mold is closed; as the two cavities are being moved closer together and before the extrudate comes into contact with one of them, injecting a first fluid between the extrudate and at least one cavity; injecting a second fluid on the opposite side of the extrudate from each cavity, to press it firmly against the wall of the cavity; removing the first fluid present between the cavity and the extrudate before end of injection of the second fluid.

A blow molding device includes: a base; an injection molding unit manufacturing a bottomed preform made of resin; a blow molding unit; a support part supporting the preform; and a conveying unit conveying the support part to the blow molding unit. The blow molding unit includes: a blow mold; a movement unit capable of moving the blow mold relative to the support part; one mold opening and closing mechanism; and a pair of mold opening and closing plates connected to the mold opening and closing mechanism. The moving unit is configured to move the blow mold in a non-coupling state to a position between the pair of mold opening and closing plates, the blow mold in the non-coupling state being not coupled to the pair of mold opening and closing plates and not located between the pair of mold opening and closing plates.

A blow molding device includes: a base; an injection molding unit manufacturing a bottomed preform made of resin; a blow molding unit; a support part supporting the preform; and a conveying unit conveying the support part to the blow molding unit. The blow molding unit includes: a blow mold; a movement unit capable of moving the blow mold relative to the support part; one mold opening and closing mechanism; and a pair of mold opening and closing plates connected to the mold opening and closing mechanism. The moving unit is configured to move the blow mold in a non-coupling state to a position between the pair of mold opening and closing plates, the blow mold in the non-coupling state being not coupled to the pair of mold opening and closing plates and not located between the pair of mold opening and closing plates.

A hollow body forming mold includes left and right half molds, a bottom of the left half mold is provided with a left avoidance slot, a bottom of the right half mold is provided with a right avoidance slot, a left bottom slider is disposed in the left avoidance slot, a right bottom slider is disposed in the right avoidance slot, and the left and right bottom sliders constitute a group of sliders. The mold design resolves a difficult problem that a fabrication hole exists during forming of a hollow body with a built-in component by using an existing conventional process The hollow body forming method has the advantages of a short forming period, the high production efficiency, good combination between a built-in component and an inner wall of an fuel tank, and the high location stability.

A hollow body forming mold includes left and right half molds, a bottom of the left half mold is provided with a left avoidance slot, a bottom of the right half mold is provided with a right avoidance slot, a left bottom slider is disposed in the left avoidance slot, a right bottom slider is disposed in the right avoidance slot, and the left and right bottom sliders constitute a group of sliders. The mold design resolves a difficult problem that a fabrication hole exists during forming of a hollow body with a built-in component by using an existing conventional process The hollow body forming method has the advantages of a short forming period, the high production efficiency, good combination between a built-in component and an inner wall of an fuel tank, and the high location stability.

A blow molding method includes: performing a primary blowing on a resin preform to form an intermediate molded product; and performing a final blowing on the intermediate molded product to form a final molded product, and at least one step of performing the primary blowing and the final blowing includes a thinning step of continuously repeatedly performing, within a predetermined time, steps of: stretching an object by blowing; and contracting stretched parts of the object by exhausting blown air.

A blow molding method includes: performing a primary blowing on a resin preform to form an intermediate molded product; and performing a final blowing on the intermediate molded product to form a final molded product, and at least one step of performing the primary blowing and the final blowing includes a thinning step of continuously repeatedly performing, within a predetermined time, steps of: stretching an object by blowing; and contracting stretched parts of the object by exhausting blown air.

A liquid blow molding method molds a bottomed tubular-shaped preform into a liquid-containing container in which a content liquid is held. The liquid blow molding method includes: a first molding step of liquid blow molding the preform into a halfway shape by supplying, into the preform that has been heated to a predetermined temperature, a first liquid at a predetermined pressure through a nozzle unit; and a second molding step, performed after the first molding step, of liquid blow molding the preform by supplying a second liquid into the preform at a predetermined pressure through the nozzle unit.