Andrew Doyle/LONDON
BRITISH AEROSPACE Airbus is studying the possible introduction of "age-forming" techniques in the manufacture of wing skins for all Airbus narrow-body aircraft, following its successful implementation for part of the upper-wing skin of the A321. The company is using a 14m-long oven supplied by Aeroform of the UK to produce the A321 part.
The use of age forming is intended to allow wing-skin sections to be made lighter and easier to install. Using the technique, the A321 skin section is produced as a single part and then "dropped" into place during wing assembly.
The high-dimensional accuracy and repeatability achieved with age forming means that the part is "stress relieved", because it does not have to be installed under load to achieve the correct aerodynamic profile of the wing.
The skins are manufactured from flat sheets of aluminium, which are vacuum formed against a 7.5t tool. According to Aeroform managing director Ian Toll, the sheets are initially "over-formed", and held in place during the precipitation-hardening cycle in the oven. They "spring" back to the intended shape when removed from the tool.
"The oven is split into eight zones of individually controlled heat," says Toll, who adds that "-each is accurate to within +/- 1.1¡C." This ensures that the skin section remains at the correct temperature along its entire length, despite the varying thickness of the tool.
Textron Aero-structures of the USA employs a similar technique in the production of the wing skins for the A330/A340 which it supplies to BAe Airbus.
Source: Flight International
