Bending Aluminum Cones for the U.S. Navy, Fleet Ballistic Missile (FBM) Program

The US Navy has 18 Ohio class nuclear powered submarines. 14 of those submarines are SSBN; ship, submersible, ballistic, nuclear; while the other 4 are SSGN; ship, submersible, guided, nuclear. These submersibles were put into commission in the 1980’s;with a 42 year +/- operational lifespan, these submarines will start to decommission at a rate of 1 hull per year starting in 2029. Seeing that the U.S. Department of Defense anticipates a continued need for sea-based strategic nuclear force, SSBN-X or the Ohio Replacement Program has been put into place by the US Navy.

A key aspect to the replacement program is the re-design, removal and replacement of each of the submersible’s 24 ballistic missiles. In late 2013, prototypes/mockups for key components of the Fleet Ballistic Missile (FBM) program, were ordered. One of these components was an aluminum cone that was to be rolled from aluminum plate into 180deg conical sections. These conical segments were then welded complete and fabricated into weldments for the supporting of the FBM third stage motors. The bending of the aluminum plate was done by a rolling process known as plate rolling. The machine was fitted with a special attachment specific to rolling conical segments that allowed the major diameter of the cone to pass through the machine faster than the cones minor diameter; this setup is key to rolling conic shapes as the cones taper and differing diameters is achieved in this fashion. The bottom rolls of the machine are capable of variable geometry positioning which also plays a detrimental role in the forming of the cones. The hardened steel rolls were coated with a special proprietary material in order to protect the surfaces of the aluminum cone segments. Once the prototypes were approved, the first production order was placed in 2015 with an extremely aggressive schedule. A 5 day turnaround was needed, from receipt of order to dock delivery of bent/rolled aluminum cones, in order to meet needs of the US Navy. The order was placed on Monday, materials were expedited and processed late into the evening Wednesday night, in order to be ready for shipment on Thursday. 12 of these Ohio Class Submarines are scheduled to be replaced over the next 13 years; SSBN-X or the Ohio Replacement Program must be fully initiated by 2016 in order to meet the 2029 deadline.


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