Patent ID: 7906062

Claim:
A process for the production of hollow bodies of thermoplastic material by extrusion blow molding, comprising: extrusion of at least two preforms in web form of plasticized material by means of a plurality of extrusion devices, wherein each of said at least two preforms are respectively extruded between an outer mold and a central mold, the outer molds each having a mold cavity, the outer molds are then closed to clamp the at least two preforms against the central mold, wherein said at least two preforms are jointly shaped within said mold cavities, wherein in a first step said at least two preforms are respectively caused to bear against a contour forming portion of the mold cavities by means of increased pressure and/or reduced pressure and are shaped out to form intermediate products, the central mold is then removed from between the outer molds and the outer molds are closed against each other, and in a second step the intermediate products are joined together to provide a hollow body, wherein a wall thickness profile is imparted to at least one preform during the extrusion operation independently of the respective other preform by nozzle gap adjustment during the extrusion operation.