Method for shaping a flat web material, and device

A method for shaping a flat web material, wherein said flat web material is largely flat or smooth and level in an initial state and, when folded in a final state, is in a periodic three-dimensional structure, said periodic three-dimensional structure having a multiplicity of folds along differently oriented folding lines and having elevations and depressions, said method having the following steps:

• said flat web material is inserted between a lower holding die and an upper holding die, wherein said holding dies are composed of flat material and have preformed kink lines, said kink lines being identical on said two holding dies and lie precisely one above the other when they are resting on said flat web material,
• moving a lower shaping die and an upper shaping die up to said holding dies from below and from above respectively, wherein said shaping dies are composed of flat material with predetermined bending lines,
• said holding dies are largely level during an insertion of said flat web material and also as said shaping dies are moved up,
• said shaping dies have bending lines precisely corresponding to one another or precisely lying opposite one another, with identical bendings along said bending lines, wherein said shaping dies are not flat but are raised by bending along said bending lines or have a shape corresponding to said three-dimensional structure to be produced with said flat web material, wherein at least some of said bending lines of said shaping dies coincide with some of said kink lines of said holding dies.