A method for manufacturing a box-shaped structure for aircrafts, and in particular for a horizontal stabilizer, using a fiber-reinforced polymer matrix prepreg composite material, said structure having a longitudinal axis, extending longitudinally between a first axial end and a second axial end, and comprising:
- a first longitudinal wall;
- a second longitudinal wall facing the first wall and arranged spaced from the first wall itself by a non-zero amount;
- and
- a plurality of spars extending longitudinally and between said first wall and second wall, connected to these latter and delimiting with the first wall and the second wall respective longitudinal cavities;
- said method comprising the steps of:
- a) laminating a first plurality of layers of said prepreg composite material on a first forming plate of a forming mold, so as to form a first skin in composite material defining said first wall;
- b) arranging a plurality of elongated support tools each having a cross section with a polygonal external profile complementary to the profile of the longitudinal cavities to be formed in said structure;
- c) laminating a second plurality of layers of said prepreg composite material on three contiguous walls of each support tool, so as to obtain elongated profiles made in said composite material, each profile having a C-shaped cross section and comprising a flange and two winglets projecting transversely from the flange;
- d) joining said profiles two by two along the respective flanges adjoining side by side respective pairs of support tools so that the profiles themselves have opposite concavities, so as to obtain said spars;
- e) longitudinally arranging the adjoined support tools and the previously obtained spars on the previously obtained first wall, in such a way that respective first winglets of the spars are coplanar in contact with said first wall, thus defining a first assembly of said structure;
- f) laminating a third plurality of layers of said prepreg composite material on a second forming plate of said forming mold, so as to form a main portion of a second skin in composite material, which second skin defines said second wall;
- g) laminating a fourth plurality of layers of said prepreg composite material on said second plate or on a third forming plate of said forming mold separate and distinct from the second plate, so as to form a closing portion of said second skin distinct and separate from said main portion and couplable to the main portion itself to define said second wall;
- h) placing at least said main portion on said first assembly so that the main portion is in contact with respective second winglets of the spars opposite said first winglets, so as to define part of said second wall extending from one of said first axial end or second axial end up to a predetermined transversal sector of the box-shaped structure axially interposed between said first axial end and second axial end, relative to said longitudinal axis, the group comprising the first assembly and the main portion defining a second assembly of said box-shaped structure;
- i) after the step h) of placing, inserting in said cavities and between said spars a series of transversal reinforcing elements, aligned with one another transversally to said longitudinal axis and at said transversal sector, for defining a reinforcing rib of said box-shaped structure arranged at said transversal sector;
- l) after step i) of inserting, placing said closing portion on a third assembly of said box-shaped structure comprising the second assembly and the reinforcing rib, coupling the closing portion to the main portion in such a way that the closing portion extends from said transversal sector to the other of said first axial end or second axial end, so that the closing portion is in contact with said second winglets of the spars and so as to define the remaining part of said second wall for closing the box-shaped structure.