Method for making hollow stiffening elements

A method for making hollow stiffening elements with co-curing technique on a structure made of composite material comprising the use of at least a lamination and polymerization spindle upon which is positioned at least one rolled section;

• the spindle having a longitudinal length greater with respect to the at least one rolled section to expose at least an exposed portion outside of a profile of the rolled section for movement of the spindle;
• said rolled section forms at least a hollow structure where the spindle is located;
• said method comprising the following operational phases:
• a) coating the spindle with at least an anti-adherent first layer;
• b) coating the spindle with at least a heat-shrinking second layer;
• c) heating the coated spindle to adhere said anti-adherent first layer and said heat shrinking second layer to said spindle, to attain a lower coefficient of friction between said anti-adherent first layer and said heat-shrinking second layer;
• d) positioning the spindle on the surface of the structure;
• e) laminating the surface through one of the at least at least one rolled section and forming the hollow structure on the spindle;
• f) moving the spindle along a longitudinal axis by taking the spindle from the exposed portions, wherein the anti-adherent first layer moves integrally with the spindle, and wherein the heat-shrinking second layer remains in a position in contact with the at least one rolled section, wherein the spindle is moveable along the longitudinal axis;
• g) inserting layers of the at least one rolled section under the exposed portions of the spindle out of the profile of the at least one rolled section positioned in step e);
• h) heating the structure obtained in steps a) though g);
• and
• i) extracting the spindle from the hollow structure by taking the spindle from the exposed portions.