METHOD OF MANUFACTURING SPARS, LONGERONS AND FUSELAGE BEAMS HAVING A VARIABLE H CROSS-SECTION

• US 20110226407A1
• Filed: 03/03/2011
• Published: 09/22/2011
• Est. Priority Date: 03/08/2010
• Status: Active Grant

• Current Assignee: Alenia Aeronautica SPA (Leonardo S.p.A.)
• Original Assignee: Alenia Aeronautica SPA (Leonardo S.p.A.)
• Inventors: Di Tommaso, Luca, Inserra Imparato, Sabato, Capasso, Luigi, Avagliano, Luigi, D'agostino, Emmanuele, Iagulli, Gianni
• Granted Patent: US 8,815,044 B2
• Time in Patent Office: Days
• US Class Current: 156/196
• CPC Class Codes: B29C 70/44 using isostatic pressure, e.g. pressure difference-moulding, vacuum bag-moulding, autoclave-moulding or expanding rubber-moulding
• CPC Class Codes: B29D 99/0007 having a variable cross-section
• CPC Class Codes: B29K 2105/246 Uncured, e.g. green
• CPC Class Codes: B29L 2031/008 having a longitudinal cross-section
• CPC Class Codes: B64C 1/065 Spars
• CPC Class Codes: B64C 2001/0072 from composite materials
• CPC Class Codes: B64C 3/185 Spars
• CPC Class Codes: Y02T 50/40 Weight reduction
• CPC Class Codes: Y10T 156/1002 with permanent bending or reshaping or surface deformation of self sustaining lamina

Abstract

A beam of fibre-reinforced curable thermosetting composite material is preliminarily assembled in an uncured condition. The beam is placed between two forming tools, namely a lower and an upper tool, shaped in such a way as to give the lower and upper flanges a predetermined shape, at least one of the flanges having a non-rectilinear profile viewed in a longitudinal vertical plane. Two longitudinally elongate rigid inserts are placed between the flanges at the sides of the web and are covered in respective airtight tubular bags. The spaces between the upper tool and the lower tool on the two opposite longitudinal sides are sealed. The open opposite ends of the tubular bags are also sealed in such a manner that the pressure applied in an autoclave during the step of curing causes the tubular bags to swell and presses them against the two opposite faces of the web and against the flanges of the beam. On completion of curing, the upper forming tool is removed and the inserts are extracted sideways.

Claims

1. A method of manufacturing a beam of composite material having a variable H cross section along its length, the beam including a lower flange, a web and an upper flange, at least one of the flanges having a non-rectilinear profile when viewed in a longitudinal vertical plane, the method including the steps of:

preliminarily assembling a beam of fibre-reinforced curable thermosetting composite material in an uncured condition;

providing a lower forming tool having a lower forming surface shaped to give the lower flange a predetermined shape;

providing an upper forming tool having an upper forming surface shaped to give the upper flange a predetermined shape, wherein at least one of said forming surfaces has a non-rectilinear profile when viewed in a longitudinal vertical plane;

providing releasable supporting means for supporting the upper tool above the lower tool with the upper and lower forming surfaces substantially aligned one above the other;

providing a pair of longitudinally elongate rigid inserts which are axially symmetrical about a vertical longitudinal plane, wherein each of the two inserts has a lower face with a profile congruent with or corresponding to the profile of the lower forming surface, an upper face with a profile congruent with or corresponding to the profile of the upper forming surface, and a side face joining the upper and lower faces;

enclosing each rigid insert in a respective airtight tubular bag;

laying the uncured beam on the lower forming tool, provisionally resting the lower flange on the lower forming surface;

fitting the two inserts into respective side spaces on the two opposite sides of the web, between the upper and lower flanges, with the side faces of the inserts facing the web of the beam to be cured, and supporting the inserts with support means fixed with respect to the lower tool;

positioning the upper forming tool above the upper flange of the beam, and supporting the upper forming tool with said releasable supporting means;

sealing laterally the spaces between the upper tool and the lower tool on the two opposite longitudinal sides of the beam;

sealing the open opposite ends of both of the tubular bags in such a manner that the pressure applied in an autoclave, in a subsequent curing step, will cause the tubular bags to swell, pressing the tubular bags against the two opposite faces of the web and against the pairs of mutually facing surfaces of the upper and lower flanges;

curing the beam in an autoclave by applying a programmed cycle of temperature and pressure;

upon completion of the curing, releasing the releasable support means of the upper forming tool, removing the upper forming tool, and extracting the inserts sideways from the beam.

2. The method of claim 1, wherein the step of sealing laterally the spaces on the two opposite longitudinal sides between the upper tool and the lower tool includes the application of two respective airtight films each sealed both to the upper tool and to the lower tool.

3. The method of claim 2, wherein the step of sealing the open opposite ends of both the tubular bags includes the steps of

sealing an upper edge of each of the longitudinal ends of each of the two bags to the upper tool,

sealing the lower edge of each of the longitudinal ends of each of the two bags to the lower tool,

sealing the central edge of each of the longitudinal ends of each of the bags to the central edge of the adjacent bag, and

sealing the outer side edge of each of the longitudinal ends of each of the two bags to the respective outer lateral film.

4. The method of claim 1, wherein the curing step is preceded by the step of:

applying a vacuum to the space between each tubular bag and the other elements to which this bag is sealed.

5. The method of claim 1, wherein the inserts are supported at their ends by end supports in a suspended condition above the lower forming surface.

6. The method of claim 1, wherein the upper tool is supported by a plurality of discrete supports, longitudinally spaced from one another.

7. The method of claim 6, wherein the supports for the upper tool include vertical standards longitudinally spaced from one another.

8. The method of claim 7, wherein the standards are associated with centering means for allowing accurate centering of the upper tool with respect to the lower tool.