Improved Fabrication Process for Spherical Acrylic Pressure Hulls.

摘要

This report describes an improved process for fabricating spherical acrylic plastic pressure hulls within close dimensional tolerances. The process consists of casting acrylic plastic hemispheres in a precision mold assembly, machining their equatorial edge and cutting polar penetrations, bonding then together with a cast-in-place equatorial joint, polishing their inner and outer surfaces, and installing an aluminum hatch and penetration plate. The cost of the improved process is approximately 50 percent less than that of the standard process, which consists of bonding together 12 thermoformed and machined spherical pentagonal shell sections. In addition, 90 percent fewer bonded joints are required, resulting in an order-of-magnitude improvement in optical qualities. A full-scale prototype with an outside diameter of 66.500 inches and an inside diameter of 58.000 inches has been constructed and shown to be acceptable for manned service to a depth 2500 feet by hydrostatic testing under sustained loading at pressures of 900, 1350, 1800, and 4000 lb/sq in. Implosion occurred after 13 minutes of sustained loading at 4000 ln/sq in and 75 F (simulated depth of 9000 feet).