METHODS OF MANUFACTURING SINGLE PIECE MULTI-SPAR BOXES OF COMPOSITE MATERIAL IN A CLOSED MOULD

• US 20160114538A1
• Filed: 05/17/2013
• Published: 04/28/2016
• Est. Priority Date: 05/17/2013
• Status: Active Grant

• Current Assignee: Alenia Aermacchi SPA (Leonardo S.p.A.)
• Original Assignee: Alenia Aermacchi SPA (Leonardo S.p.A.)
• Inventors: IAGULLI, Gianni, TOTARO, Giuseppe, AVAGLIANO, Luigi, CERRETA, Pietrantonio
• Granted Patent: US 10,449,733 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B29C 70/34 and shaping or impregnating by compression , i.e. combined with compressing after the lay-up operation
• CPC Class Codes: B29C 70/345 using matched moulds
• 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: B29C 70/443 and impregnating by vacuum or injection
• CPC Class Codes: B29D 99/0014 provided with ridges or ribs, e.g. joined ribs
• CPC Class Codes: B29L 2031/3076 Aircrafts blades, propellers B29L2031/08
• CPC Class Codes: Y02T 50/40 Weight reduction

Abstract

Methods of making single piece multi-spar boxes made of composite material for aircraft are provided. Such methods include providing outer spars of the boxes which are made with a C-shaped cross-section such that the spars, during curing, are moulded on the inside onto rigid, outer, lateral forming tools. As a result it is possible to obtain very precise outer profiles and positions of the spars.

Claims

1-9. -9. (canceled)

10. A method of manufacturing a single piece multi-spar box made of composite material for aircraft, comprising:

placing a first panel of composite material on a first plate and a second panel of composite material on a second plate;

suspending, above the first panel, one or more intermediate spars of composite material arranged between elongated inner tools which are each enclosed inside a respective pressurisable impermeable tubular bag;

arranging two outer lateral spars of composite material with a C-shaped cross-section inside two respective C-shaped seats formed in two respective rigid, lateral, outer tools, where the two outer lateral spars have respective concavities directed towards each other and the two seats have respective concavities directed towards each other;

moving the lateral outer tools towards each other such that the inner tools wrapped in pressurisable bags are partially inserted inside the C-shaped outer spars;

bringing the spars into contact with the first panel and the second panel so that the multi-spar box to be polymerized is closed between the first plate, the second plate and the two lateral outer tools;

sealing open opposite ends of the tubular bags so that the pressure applied in an autoclave during a following polymerization step causes expansion of the tubular bags, compressing them against bases and cores of the spars; and

curing the box in an autoclave by applying a programmed cycle of heat and pressure.

11. The method of claim 10, wherein the step of bringing the spars into contact with the first panel and the second panel further comprises the steps of:

simultaneously lowering the inner tools and the lateral outer tools so as to bring the bottom bases of the spars into contact with the bottom panel;

transferring the second plate with the second panel above the spars;

lowering the second plate so as to bring the top panel into contact with top bases of the spars; and

locking the two lateral outer tools to the first plate and to the second plate, so as to form, together with the plates, a closed mould.

12. The method of claim 11, wherein in the closed mould condition the lateral outer tools are arranged vertically between the first plate and the second plate so as to support the second plate.

13. The method of claim 10, wherein one or more intermediate spars is/are retained on one or more central inner tools by magnets which cooperate with plates of ferromagnetic material which are incorporated in one or more inner tools.

14. The method of claim 10, wherein the inner tools and the lateral outer tools are suspended at their opposite ends from supports.

15. The method of claim 14, wherein the supports for the ends of the inner tools and outer tools are supported by the first plate.

16. The method of claim 10, wherein the outer spars are temporarily fixed to the lateral outer tools by removable pins which are inserted through the outer spars and into through-holes provided in the lateral outer tools.

17. The method of claim 10, wherein the outer spars are inserted partially inside the respective C-shaped seats of the lateral outer tools with a predetermined minimum play and wherein the spars, in this partially inserted condition, have end portions of their top and bottom flanges which project outside the respective C-shaped seats.

18. The method of claim 10, wherein the step of sealing the open opposite ends of the tubular bags further comprises the steps of:

sealing a top edge of each of the longitudinal ends of each of the tubular bags together with the second plate;

sealing a bottom edge of each of the longitudinal ends of each of the tubular bags together with the first plate;

sealing together vertical edges of each of the longitudinal ends of adjacent tubular bags; and

sealing vertical edges of the tubular bags adjacent to the outer lateral spars together with respective outer bag-film sheets, which outer bag-film sheets are each sealed together with the first plate and the second plate and cover on the outside each of the two rigid, lateral, outer tools.