UNITED TECHNOLOGIES CORP STRATFORD CT SIKORSKY AIRCRAFT DIV
This report summarizes a series of U.S. Army sponsored Manufacturing Methods and Technology, MM and T programs which were ultimately aimed at evaluating and implementing into production the use of the Continuous Seam Diffusion Bonding, CSDB, process to fabricate reliable, lower cost titanium alloy 6Al-4V helicopter main rotor blade spars. The current production process for manfacturing the UH-60A Army BLACK HAWK helicopter main rotor blade spars uses a plasma arc weld to join a cold brake formed cylindrical shape titanium sheet pre-form. The titanium pre-form is subsequently creep formed to the required final contour. The subject program has investigated and fabricated various shape spar pre-forms and manufacturing operations that could be easily cold brake formed from flat titanium sheet material into a configuration that is capable of being continuous seam diffusion bonded and subsequently creep formed to the final contour. Tooling which is capable of clamping and satisfactorily bonding the selected configuration pre-form shape has been designed and constructed. Process parameters relating to bonding variables and material condition have been evaluated. The subject program has successfully diffusion bonded three, ten foot length BLACK HAWK spar tubes, and non-destructively inspected, NDI, ten bonded spar tubes for any abnormalities.