Jig and method of manufacturing aircraft frames in a composite material

Abstract

The present invention relates to a jig for the manufacture, by means of injection and curing processes, of preforms of composite material frames for aircraft fuselages by using the RTM (resin transfer molding) technology. Two preforms are thus manufactured, one with a C shaped section and another with a L shaped section, together with the preforms of the stabilization ribs for stabilizing the web of the frames and the preform of the roving or staple fiber to cover the gap between the C shaped preform and the L shaped preform. Theses preforms are previously manufactured by any known process for manufacturing preforms. According to a second aspect, the present invention relates to a method of manufacturing composite material load frames for aircraft.

1 . A jig for injecting and curing preforms of an aircraft fuselage composite material frame ( 2 ), characterized in that the mentioned jig shapes preforms comprising at least one C shaped preform ( 3 ), at least one L shaped angular preform ( 4 ), at least one stabilization rib ( 5 ) for stabilizing the web of the frame ( 2 ) and at least one preform ( 6 ) of the roving or staple fiber in the joint between the C shaped preform ( 3 ) and the L shaped angular preform ( 4 ), and in that the mentioned jig comprises an injection and curing jig ( 7 ) injecting and curing resin for the manufacture of the preforms, a vacuum system ( 8 ) allowing to shape the previous preforms by means of applying vacuum and a heating and closing system such that the section of the structure of the frames ( 2 ) by means of the previous preforms is integreated in one part. 
     
     
         2 . A jig for injecting and curing preforms of an aircraft fuselage frame ( 2 ) according to  claim 1 , characterized in that the preforms ( 3 ,  4 ,  5  and  6 ) are manufactured by means of RTM (resin transfer molding) technology. 
     
     
         3 . A jig for injecting and curing preforms of an aircraft fuselage frame ( 2 ) according to a  claim 1 , characterized in that the preforms ( 3 ,  4 ,  5  and  6 ) comprise fabric and reinforcements with unidirectional tape in the inner flange to increase their moment of ineitia and, consequently, their rigidity. 
     
     
         4 . A jig for injecting and curing preforms of an aircraft fuselage frame ( 2 ) according to  claim 1 , characterized in that the injection and curing jig ( 7 ) comprises a tub ( 10 ) in which there are placed the remaining elements shaping the jig ( 7 ) and the preforms ( 3 ,  4 ,  5  and  6 ) are placed, one male parts ( 11 ) assembly which is placed under the C shaped preform ( 3 ), an assembly of upper male parts ( 12 ) shaping the frame ( 2 ) on the side of the outer flange, an assembly of upper male parts ( 13 ) shaping the frame ( 2 ) on the side of the inner flange, an assembly of male parts ( 14 ) which are arranged on both sides of the stabilization ribs ( 5 ) for stabilizing the web of the frame ( 2 ) and a cover ( 15 ) sealing the jig ( 7 ) against the tub ( 10 ). 
     
     
         5 . A jig for injecting and curing preforms of an aircraft fuselage frame ( 2 ) according to  claim 1 , characterized in that the vacuum system ( 8 ) comprises an assembly of sealing rubbers ( 16 ) arranged at the upper part of the tub ( 10 ), one vacuum pump ( 17 ), a system of tubes ( 20 , 22 ) joining the jig ( 7 ) with a resin injection machine ( 19 ) and with the vacuum pump ( 17 ), and a vacuum circuit ( 21 ) closing the jig ( 7 ) and from which the tubes ( 20 ,  22 ) joining said jig ( 7 ) with the vacuum pump ( 17 ) and with the resin injection machine ( 19 ) come out. 
     
     
         6 . A jig for injecting and curing preforms of an aircraft fuselage frame ( 2 ) according to  claim 1 , characterized in that the heating and closing system comprises a hot plate press ( 18 ). 
     
     
         7 . A jig for injecting and curing preforms of an aircraft fuselage frame ( 2 ) according to  claim 1 , characterized in that the heating and closing system comprises an autoclave. 
     
     
         8 . A method of manufacturing composite material aircraft fuselage frames ( 2 ) comprising the following steps:
 a) Placing and closing the injection and curing jig ( 7 ).   b) Placing the jig ( 7 ) on the heating and closing system.   c) Connecting the vacuum system ( 8 ).   d) Applying pressure on the closing and heating system to close the jig ( 7 ) and ensure tightness.   e) Heating the jig ( 7 ) to the injection temperature.   f) Applying vacuum to the jig ( 7 ), through the vacuum system ( 8 ).   g) Injecting the resin.   h) Constricting the tubes ( 20 ) once the resin has overflowed through the injection points.   i) Applying compacting pressure to the injection machine ( 19 ).   j) Heating gradient up to the curing temperature.   k) Maintaining the curing temperature.   l) Cooling.   m) Demolding.