Patent ID: 11858182
Assignee: FITS HOLDING B.V.
Field: Other special machines (Mechanical engineering)
Classification: CPC B | IPC B

Claim 8:
9. Method for manufacturing a sandwich panel in a press having press plates, which sandwich structure comprises at least one foam layer of a first thermoplastic and cover layers, the method comprising the steps of:
a) providing a starting structure comprising at least one layer of a first thermoplastic and two cover layers; wherein said at least one layer of said first thermoplastic comprises a physical blowing agent;
b) contact heating said starting structure between the press plates of the press to a foaming temperature while maintaining pressure on the starting structure by the press plates;
c) at said foaming temperature, foaming of said at least one layer of said first thermoplastic comprising the physical blowing agent by moving the press plates a predetermined distance apart, while maintaining a pressure on the structure being foamed, wherein the volume is made to increase to a final volume and then kept constant, thereby obtaining said sandwich panel;
d) initially cooling of said sandwich panel at a constant final volume while pressurized in contact with the press plates to a temperature below the glass transition temperature of the first thermoplastic comprising the physical blowing agent by conversion of hot pressurized water in the press plates into steam by means of a controlled expansion valve;
e) final cooling of the initially cooled sandwich panel of step d); and
f) opening of the press and removing the cooled sandwich panel of step e) from the press.