Patent ID: 9387604
Filing Date: 2016-07-12
CPC Classification: B29C

Claim Text:
1. A method for making a molding core for the manufacturing of a part made of composite material, the molding core having an elongated form, corresponding to a hollow cavity of said part to manufacture, one dimension, the length Ln, being great with regard to the characteristic dimensions, widths In and heights hn, of cross sections of said molding core, said molding core comprising one or more local curvatures, in the longitudinal direction of the molding core, on a surface of the molding core and/or comprising changes in the forms and sizes of cross sections of the molding core depending on a position along the length of said molding core, said method comprising the steps of: producing a cylindrical bladder, a cylindrical part of which is produced by extrusion-pultrusion of an elastomer such that all cross sections of said cylindrical bladder are identical within manufacturing tolerances, made of elastomer, giving rise to an internal volume, having at least the length Ln of the molding core to be made and having an external perimeter with a corresponding cross section, constant within the manufacturing tolerances, and equal to or lower than a lowest of the perimeters of the cross sections of the molding core to be made, the bladder having a shape and size that are different than a shape and size of the molding core to be made; then conforming the bladder in a core mold, said core mold comprising a hollow cavity with shapes of at least the local curvatures in the longitudinal direction of the molding core to be made, and having the forms and sizes of each cross section all along the length of the molding core to be made, by deforming the bladder by applying a differential pressure ΔPg between the internal volume of said bladder at a pressure P filling the bladder with a granular material and then applying a differential pressure ΔPe between the internal volume and the external space of the bladder, such that the internal space is at a pressure below the external space.