Welding Technologies used in Rocket Engine Manufacturing

ROBOT WELDING

Robot Welding Machine

Robot welding is used for the fabrication of regeneratively cooled rocket nozzle extensions. These nozzles are constructed entirely from rectangular tubes, spiral wound around a mandrel and automatically precision welded together into the nozzle profile.

The HM-7B rocket engine nozzle is constructed this way and comprises 242 rectangular section cooling tubes having a wall thickness of 0,32 mm. The width of each tube varies along its length to optimise on coolant flow properties, thereby enabling a uniform heat distribution throughout the nozzle.

Using a robot welder, the cooling tubes are welded together to form an integral spiral-welded nozzle structure without the use of any filler material.

The robot welder features a laser-led TIG welding head that detects the welding gap between tubes as well as any tube offset and regulates the welding parameters accordingly.

Each nozzle has a welded seam length of approximately 730 metres (about the length of seven football fields).

The regeneratively cooled nozzles of the HM-7 and HM-7B rocket engine have been produced this way since 1979 and have been used on all upper stages of the Ariane family.

 

Nozzle constructed from rectangular tubes

Completed nozzle after tubes welded together by robot TIG welder

HM 7B Rocket Engine

The HM-7 series of engine use a regenerative cooling system for the combustion chamber and throat assembly, i.e. most of the liquid hydrogen flow is routed through 128 longitudinal channels integrated in the double-wall structure.

The nozzle is cooled by a simple process known as dump cooling, whereby remaining hydrogen flow is routed to the 242 spiral-welded tubes forming the nozzle structure, then escapes through 726 micro-nozzles set along the base of the nozzle rim. Although these gases do not undergo combustion, they are heated during their trip and contribute to the overall thrust.

 

ELECTRON BEAM WELDING

The main feature of the electron beam welding technique is the very high quality seams that are indispensable in the aerospace industry.

Electron beam welding is performed in a vacuum with a very high performance density in the focus of the beam. 150,000 Volts are distributed on only 0,6 mm density in the welding head. This enables a consistently high quality weld while significantly reducing the processing time.

The electron beam welding process is computer controlled and electrically and mechanically regulated.

Our electron beam welding facility is used for

	The combustion chambers of the Aestus and Vulcain 2 engines.
	The cryogenic propellant valves for the Ariane 5 core stage.
	The HM-7B combustion chamber for the Ariane 5 ESC-A upper stage.
	Products under technological development.
	Thruster casings for aerospace applications, such as for Lear Jets.

 

Vulcain 2 Combustion Chamber

HM-7B Combustion Chamber

 

TIG HAND WELDING

TIG hand welding is used for the welding of rocket engine combustion chambers, fluid manifolds, expansion nozzles and associated flanges and attachment brackets. Typical welded assemblies include:

	The Vulcain combustion chamber for the Ariane 5 core stage, H2 inlet and outlet manifold, retainer brackets.
	The Aestus thrust chamber for the Ariane 5 bi-propellant upper stage, inlet manifold and Ox cover dome.
	The HM-7B combustion chamber for the Ariane 5 ESC-A cryogenic upper stage, inlet and outlet manifolds.
	Expansion nozzles and their and their associated fittings, interface flanges and supports.

If you require more detailed information on any of our products or services, then please contact us, indicating your particular areas of interest or intended application. Your enquiry will receive our best attention.