Design of Welding Fixture for Head End Sub-Assembly of Motor Case

This paper deals with the design of the welding fixture for the head end sub-assembly of a rocket motor case. The head end sub-assembly consists of four parts namely Y-Ring, Dome, Igniter Boss and the Fore skirt ring that have to be welded to each other with a specified tolerance and weld quality. The material used in the manufacture of different parts of head end sub-assembly is Maraging steel which is one of the most commonly used material in the field of aerospace. All the welding processes are carried out in the presence of the Copper Arsenic back-up support bar to ensure the quality of weld is as per the requirement. The optimum thickness of the back-up support bar is determined and with in-process purging facility in the copper-arsenic bar ensure sound weld. Modeling of all the parts of head end sub-assembly and the welding fixture is carried out using UNIGRAPHICS NX8.0.