Original Date: 07/21/2003
Revision Date: 01/18/2007
Best Practice : Automated Frame and Cylinder System
Electric Boat Corporation, Quonset Point Facility spent considerable time and effort in staging areas for welding and outfitting operations in submarines. To improve overall quality and ease of operations, the company moved from a “stack and wrap” approach to an Automated Frame and Cylinder System.
A key element in building high quality, cost-effective submarines is the fabrication and assembly of pressure hull frames and cylinders. Electric Boat Corporation, Quonset Point Facility (EBQP) previously spent considerable time and effort in staging areas for welding and outfitting operations. Each assembly required custom spider fixtures, temporary attachments, spacers, and numerous hydraulic jacks. If any operation required turning a component, a 10- to15-person rigging crew was needed. Safety was a problem, and the time required to fit was lengthy. To improve overall quality and ease of operations, EBQP moved to an Automated Frame and Cylinder (AFC) System shown in Figure 2-2.
The AFC System is a series of fixtures enabling repeatable, easily configurable, and reachable frame and hull cylinder fabrication and frame-to-hull pairings for cylinders 32' to 40' in diameter. The fixtures hold the hull’s circularity and rotate entire hull sections to position the sections for ease of welding and finishing operations. Several of the fixtures can elevate and rotate 180° allowing second-side welding. All fixtures have lights, pre- heaters, power, elevators, and work platforms. Partially automated welding equipment is part of the AFC System.
The resultant circularity accuracy of the hull cylinder and frame was substantially better and easier to maintain during welding operations. Total fabrication time decreased from 20,000 hours to 1,400 hours, an order of magnitude reduction. Every operation had an order of magnitude decrease in time to fabricate an assembly. The frame fabrication time decreased from 3,000 hours to 250 hours, hull fabrication from 4,000 hours to 279, hull-to- frame assembly from 8,000 hours to 459, and pairing the cylinders from more than 6,000 hours to 528. In the recent Virginia Class of boats, process improvement continues and has decreased total cost more than 25% in the first three boats.
Figure 2-2. Automated Frame and Cylinder System
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