By innovatively applying new welding technologies, the sandwich nozzle will be less expensive to manufacture, while becoming more reliable, thus significantly reducing the risk of defects. In the future, this new technique may also be applied to rockets other than Ariane.
The current Ariane rockets have many hundreds of thin tubes welded next to each other to form a large cone or “sandwich nozzle.” A large manifold is welded on top of this structure, manufacturing that requires skilled welders with a high level of craftsmanship – which Volvo Aero has. However, the process is time-consuming and has some disadvantages.
The new structure (SWEA Sandwich Nozzle), developed by Volvo Aero, is entirely smooth on the inside – and does not have a manifold. The result is a substantially stiffer and more robust sandwich nozzle. Reliability is enhanced. The risk of the sandwich nozzle succumbing to defects is drastically reduced. In addition, the cost of the sandwich nozzle is reduced markedly.
The method is based on laser welding of thin sheet metal and fabrication of metal structures using laser metal deposition, (MD). For this design, no less than 15 km of MD welding is used to build a “reinforcement jacket,” a load carrying structure weighing 70 kg on a very thin cooling structure. This is globally unique for the sandwich nozzle.
Another innovation is the use of ultra-sound-controlled milling, which achieves precision machining to hundredths of a millimeter in sheet metal with a thickness of 0.6 mm.
In early 2009, the sandwich nozzle will be tested “live” on the Ariane’s Vulcain 2 engine, after slightly more than four years in development. The new technologies have resulted in some ten new patents.
To date, the new technologies have been verified in a new automated robot welding cell at a research institute in Denmark. However, plans are now in place to construct a similar cell at the Production Technology Center at the Innovatum Technology Park in Trollhättan, in collaboration with the ESA (European Space Agency). A prerequisite for this decision is continued Swedish participation in the Ariane program.
“SWEA is an excellent example of how we assist our space-propulsion customers in Europe, at the same time as our space-propulsion operations provide us with competitive advantages, which we most recently benefited from when we secured several large contracts for civil aircraft engines. This also demonstrates that we can and are prepared to take an active role in the further development of the Ariane rocket,” comments Staffan Zackrisson, President of Volvo Aero.