Patent ID: 6923928

Claim:
A method for modifying the shape of hollow boards of thermoplastic material having at least one open cavity in an interior of the board open toward a board edge, wherein the cavity in the interior of the board is sealed at the board edge and is thereby closed off to the exterior in a substantially gas-tight way, the method comprising softening by heating the hollow board whose shape is to be modified and modifying the shape of the hollow board in the softened state by external loading with a shaping pressure while the cavity is closed off to the exterior in a substantially gas-tight way, and sealing the cavity while leaving open at least one supply opening for the filling medium to be supplied to the cavity, or, after complete closure of the cavity, introducing at least one supply opening for a filling medium into the wall of the cavity and supplying the cavity which is closed off to the exterior in a substantially gas-tight way with a filling medium whose temperature surpasses the initial temperature of the hollow board whose shape is to be modified, and modifying the shape of the hollow board by external loading with the shaping pressure while the cavity is filled with the filling medium.