Automation Speeds A380 WING ASSEMBLY

Manufacturing Engineering, Mar 2005 by Hogan, Brian J

Building this aircraft's large wing structures required development of unique equipment and processes

The prime contractor for supplying automation tools to the Airbus plant in Broughton, UK, which is assembling the wings of what will be the world's largest commercial aircraft-the A380-is Electroimpact Inc. (Mukilteo, WA). Wing assembly occurs in several phases:

* Wing-panel assembly (Stage 00), which employs four 165-meter-long automated wing-skin production lines using Electroimpact's E4380 riveting-bolting machines;

* Wing-panel manipulators, which use servo hydraulic arms to position the panels for the next stage;

* Wing-assembly production (Stage 01), which uses a four-story-high jig that incorporates Electroimpact's HAWDE (Horizontal Automated Wing Drilling Equipment), a portable CNC drilling machine, and hydraulically operated remote-tool/worker-access platforms. This equipment works in conjunction with the mobile GRAWDE (Gear Rib Automated Wing Drilling Equipment) system used to attach the undercarriage to the lower wing.

Electroimpact collaborated with Bosch Rexroth (Hoffman Estates, IL) to provide hydraulic and linear-motion solutions, because Rexroth could meet the necessary technology specifications and schedule requirements. Electroimpact needed to phase-in machinery delivery as the facility ramped up operations to position and drill the approximately 180,000 holes needed to produce a single Airbus 380 wing box, then insert rivets and bolts. A higher level of automation enables the Broughton plant to employ a process-flow model to produce four pairs of wings a month.

When the Airbus A3 80 takes wing in 2005, it will be the largest commercial aircraft in the world-and the only twin-deck, four-aisle jet in the air. The base passenger design will seat 555 in three classes, and the triple-decker freighter design will haul up to 150 tons (165 t). By comparison, the US military's tank-transporting C-5 Galaxy hauls a maximum 135-ton (149 t) payload.

The A380's wingspan is 261' (79.6 m), versus the C-5's 223' (68 m). Each wing stretches 119' (36.3 m) from wing tip to fuselage; together, they hold 41,000 gal (155,197 L) of fuel, plus the landing gear. The large wing surface area-9100 ft^sup 2^ (845 m^sup 2^)-improves takeoff and landing performance.

The wing-manufacturing process for the A380 consists of creating a framework from spars and ribs-the wing structure-which is eventually covered with metal panels. Spars run the length of the wing. In addition to front and rear spars, a 21' long × 6' wide (6.4 × 1.8 m) spar runs down the wing's center. Ribs cross the spars, extending from the leading to the trailing edges of the wing. Panels consisting of an aluminum alloy skin reinforced by stringers are attached to this framework.

Panels are produced concurrently in a separate operation. First, skins are formed to the proper curvature. Stringers are then attached to the skin by E4380 riveting-bolting machines in the Stage OO cell. Completed panels are moved to the structure for assembly. After being loaded into a jig, the panels are positioned, drilled, countersunk, riveted, or bolted with titanium lockbolts onto the predrilled framework. The A380's upper wing uses the largest, (111' or 34-mlong) single skin.

This process is both labor and automation-intensive-a complete "wing box" takes weeks to produce, which is still fast by industry standards.

Construction of the A3 80's wings presented several significant challenges for the Airbus manufacturing team in Broughton, and for Electroimpact.

For the Airbus programs, Electroimpact choose to work with Bosch Rexroth for its hydraulic and linearmotion solutions and applications expertise, as well as the company's distributor, Pacific Power Tech (Seattle).

"The assembly process is done in two stages," explains Electroimpact's Ben Hempstead, mechanical engineering lead. "For Stage 00, Electroimpact provided four lines of fixtures for building up the upper and lower wing panels. This is a highly automated process in which riveting-bolting machines traverse the panels attaching stringers to the skin. Virtually no manual labor is required in this cell."

Next, the panels are moved to the structural wing-assembly process. The size and weight of a completed panel-up to 111' long and weighing as much as 8818 Ib (4003 kg)-poses a big problem. "Using cranes doesn't work," says Electroimpact's Theodore Karagias, project engineer. "The wing panels distort when suspended from the cranes."

Instead, Electroimpact devised a multiarm manipulator to maintain the panel's proper form and provide precise positional control while presenting the panel to the wing structure for fastening.

The Stage 01 structural wingassembly process is more labor-intensive than the previous operation. Assembled skin panels are positioned by the manipulator into four-storyhigh jigs that contain other wing parts-ribs, spars, and leading and trailing edges. For the upper wing, a combination of mobile drilling machinery (HAWDE) and manpower accessibility is required over the large surface area of the upper wing panels. For the lower wing, holes as large as 1.25'' (31.75-mm) diam are drilled for bolting the lower wing skins to undercarriage reinforcements.