SEALING OF PROPELLANT CONTAINERS BY ULTRASONIC WELDING.
AEROPROJECTS INC WEST CHESTER PA
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Ultrasonic ring welding was used to make elliptical weld closures for propellant containers having an elliptical cross section, with a relationship of less than 2 to 1 between the major and minor axis dimensions of the ellipse. The original container design was modified to include an 0.015inch-wide flange at its open end. Component materials selected were 0.010-inch Type 3003-0 aluminum alloy for the container, and 0.005-inch Type 3003-H19 aluminum alloy for the flat cover. The components were ultrasonically cleaned before being welded on a 4-kilowatt 15-kc torsional welder. Equipment modifications included a special welding tip and a welding anvil with a positioning recess for the weldment. Initial feasibility experiments having been successful, Picatinny Arsenal was provided with sample welded assemblies for further evaluation, these samples having been welded at machine settings of 2200 watts electrical power input to the ultrasonic transducer, 450 pounds clamping force, and 0.12-second weld pulse interval. Prior to welding, half of the samples had been filled with calcium chloride, and half with Hercules Pistol Powder. Metallurgical evaluation indicated sound bonds, and hermetic sealing was verified by helium-leak and water-submersion tests. Author