Method of making a flat building component

1. A method of making a thin construction element in sandwich lightweight construction and having a high-quality surface, the method comprising the following steps:

a) providing a substrate film of PMMA or ABS having a thickness between 0.2 mm and 13 mm,

b) deep-drawing the substrate film and placing the deep-drawn film into a cavity of a lower die part of a die such that bottom and side walls of the cavity are covered by the substrate film,

c) providing granular starting material in the form of loose particles of an expandable particle foam,

d) only partly expanding the particles outside the die,

e) introducing the partly expanded particles into a the cavity of the lower die part on top of the deep-drawn substrate film in the cavity and fitting an upper die part to the lower die part to close the cavity on all sides,

h) heating the lower part of the closed die with a heating device to a predetermined temperature with the cavity closed on all sides to conduct heat from the lower part through the substrate film to the partly expanded particles and thereby further expand the partly expanded particles into a completely expanded particle foam that bonds to the substrate film,

i) curing the completely expanded particle foam in the closed die into a molded article, and

j) opening the closed die and removing the molded article from the cavity of the die.

2. The method according to claim 1 , further comprising the step of:

k) after step c and before closing the cavity, applying a cover layer on a side of the partly expanded particles facing away from the substrate film.

3. The method according to claim 1 , further comprising the step of:

l) processing the molded article into a construction element.

4. The method according to claim 1 , wherein the cured-particle foam has a wall thickness between 1 cm and 30 cm.

5. The method according to claim 1 , wherein the construction element is configured as a vehicle part for a motor vehicle, a commercial vehicle, or a trailer, like an interior fitting part, cargo compartment cover, cladding part, engine hood, roof element or roof segment, vehicle wall, or vehicle wall element.

6. The method according to claim 1 , wherein the expandable particle foam is of expandable polystyrene, polypropylene, or polyether ether ketone.

7. The method according to claim 1 , wherein before step h) , the following step is performed:

m) positioning reinforcing elements as tie rods in the lower die part such that after the introduction of the partly expanded particles into the lower die part, the partly expanded particles surround the reinforcing elements.

8. A method of making a thin construction element in sandwich lightweight construction and having a high-quality surface, the method comprising the following steps:

a) providing a substrate film of PMMA or ABS having a thickness between 0.2 mm and 13 mm,

b) deep-drawing the substrate film and placing the deep-drawn film into a cavity of a lower die part of a die with the substrate film such that a bottom wall and side walls of the lower die part are covered by the substrate film,

c) providing granular starting material in the form of loose particles of an expandable particle foam,

d) only partly expanding the particles outside the die,

e) introducing the partly expanded particles into the cavity of the lower die part on top of the deep-drawn substrate film,

h) heating parts of the die with the cavity being closed on all sides with a heating device to a predetermined temperature to further expand the partly expanded particles into a completely expanded particle foam that bonds to the substrate film, the further expansion of the partly expanded particles being triggered by the predetermined temperature of the die,

i) curing the completely expanded particle foam to cure in the die into a molded article, and

j) opening the die and removing the molded article from the cavity of the die.