Patent ID: 7128800

Claim:
A vacuum forming machine for manufacturing a duplex twin-sheet element from first and second continuous webs of thermoplastic material, the vacuum forming machine comprising: means for conveying the material webs in a conveying direction parallel to each other; a twin-sheet frame disposed between the material webs, the twin-sheet frame comprising a plurality of frame sections defining an open interior and including a frame section that is movable relative to the other one or more frame sections such that the movable frame section can be moved for conveying the twin-sheet element out of the twin-sheet frame; and a tensioning frame movable between a first position where the tensioning frame is spaced from the material webs and a second position where the tensioning frame engages at least one of the material webs for loading the material webs and the twin-sheet frame and for creating closed chambers at least partially defined by sections of said thermoplastic material webs to be formed.