Patent ID: 7306761

Claim:
A method of molding a composite sandwich structure, the method comprising: (a) placing a preform in a mold, where the preform comprises a first sheet and a second sheet and a plurality of extensible threads extending between the first sheet and second sheet, where the mold comprises a first portion and a second portion, and where the first sheet is in the first portion and the second sheet is in the second portion; (b) placing a diaphragm between the first sheet and the first portion of the mold, where the diaphragm extends to at least an outer periphery of the first portion, and where there is a first chamber between the diaphragm and the first portion and a second chamber between the diaphragm and the second portion; (c) non-permanently adhering the first sheet of the preform to the diaphragm and non-permanently adhering the second sheet to the second mold portion; (d) creating a pressure differential between the second chamber and the first chamber by reducing the pressure in the second chamber; (e) using the pressure differential to feed a resinous compound into the second chamber to coat the extensible threads and surfaces of the first sheet and second sheet capable of being infused; (f) ceasing the feeding of the resinous compound into the second chamber; (g) ceasing the reduction of the pressure in the second chamber to substantially equalize the pressures in the first and second chambers; (h) creating a second pressure differential between the second chamber and the first chamber by comprising the pressure in the first chamber below that in the second chamber, thereby causing the diaphragm and, hence, the first sheet, to move away from the second sheet, thereby causing the extensible threads to extend; (i) maintaining the second pressure differential; and (j) allowing the resinous compound to set and cure.