Method To Achieve A Stiffened Curved Metallic Structure And Structure Obtained Accordingly

Abstract

The invention relates to a process for making a reinforced curved metallic structure, made from a heavy-gauge or plate-gauge sheet of an aluminium alloy containing scandium. The process consists in combining forming ( 200 ) and machining ( 300 ) steps, the forming step ( 200 ) giving the structure curvature(s) and the machining step ( 300 ) producing a network of ribs for reinforcing the structure. A finishing step ( 400 ) can complete the preceding steps. Such a process makes it possible to obtain a monobloc metallic structure with good mechanical properties simply and quickly. Application to the manufacture of a reinforced curved metallic structure of an aircraft subassembly.

1 - 13 . (canceled) 
     
     
         14 . Process for making a reinforced metallic structure with uniaxial (Ps) or biaxial (P 1 , P 2 ) curvature in monobloc form, characterized in that it consists in forming as heavy-gauge or plate-gauge sheet an aluminium alloy material containing scandium, and then in combining steps of forming ( 200 ) and of machining ( 300 ) of the said sheet, the forming step ( 200 ) giving the curvature(s) and the machining step ( 300 ) producing a network of reinforcing ribs ( 35 ,  41 ,  42 ,  51 ,  61 ,  62 ). 
     
     
         15 . Production process according to  claim 14 , in which the machining step ( 300 ) is performed after the forming step ( 200 ). 
     
     
         16 . Production process according to  claim 14 , in which the machining step ( 300 ) precedes the forming step ( 200 ). 
     
     
         17 . Production process according to  claim 14 , in which the machining step ( 300 ) is 3D and 5-axis machining. 
     
     
         18 . Production process according to  claim 14 , in which the forming ( 200 ) is hot forming. 
     
     
         19 . Production process according to  claim 18 , in which the hot-forming step is shaping with a punching ( 4 ) and stamping ( 6 ) tool heated to the same temperature as the sheet. 
     
     
         20 . Production process according to  claim 19 , in which the tool is hollow and/or made of a ceramic material. 
     
     
         21 . Production process according to  claim 18 , which the thermal contact between the die ( 6 ) and the sheet to be formed ( 2 ) is minimized by dimpling ( 6   c ) at the edge ( 6   c ) of the die ( 6 ). 
     
     
         22 . Production process according to  claim 18 , in which the hot forming ( 200 ) is performed by pressing the punching tools onto the die at a temperature of between 325 and 350° C. 
     
     
         23 . Production process according to  claim 18 , in which the hot-forming step ( 200 ) is completed by retraction of the stamping tools ( 4 ,  6 ) followed by slow cooling of the form obtained. 
     
     
         24 . Production process according to  claim 14 , in which the aluminium alloy is an Al—Mg—Sc alloy with proportions of magnesium and of scandium, respectively, less than 8% and 0.5%, preferably, respectively, between 2% and 7% and between 0.01% and 0.45%, and even more preferentially within the ranges 3-6% and 0.015-0.4%. 
     
     
         25 . Production process according to  claim 14 , which the process is finalized by a finishing step ( 400 ). 
     
     
         26 . Reinforced curved metallic structure of an aircraft subassembly, characterized in that it is made by performing the process according to  claim 14 .