This project will improve insert and panel fit-up processes to avoid significant rework and to reduce plate distortion due to welding. Ingalls Shipbuilding photo
This Navy Metalworking Center (NMC) ManTech project is improving the fit-up and welding of DH-36 thin plate components to produce panels on DDG 51 class ships.
Significant distortion is often associated with the welding of inserts into thin panel plates used in DDG 51 Class production. Both, the shape of the cut-out opening for the insert and the shape of the insert deviate from drawing specifications due to plate movements from residual stress and thermal cutting distortion. The resulting mismatch between the plate opening and insert results in insert weld joints with poor fit-up and excessive weld root gaps. These oversized weld root openings require large welds and excessive heat input, which can cause significant weld distortion. Therefore, the need to improve the insert and panel fit-up process has been identified as a high priority in addressing ship affordability.
The Navy Metalworking Center is focusing on a three-step process to install inserts with resultant precise weld root openings. The first step is to rapidly measure the insert opening while the plate is being processed on the panel line. The second step is to use the dimensional output of the opening measurement as an input to a CNC or robotic milling cutter that will be used to trim the edges of an oversized insert plate to accurately fit into the actual panel opening. The third step is to develop techniques and tooling, based on insert shape, to minimize distortion during the welding process.
Implementation of the project results will reduce fit-up time and improve quality, avoid costs associated with mitigating panel distortion, and enhance panel line capability for DDG 51 Class thin panels. Huntington Ingalls Industries - Ingalls Shipbuilding estimates more than 40,500 man-hour savings in the next five years. The five-year savings estimate is $2.63M related to reduction of thin plate distortion.
A scaled prototype measurement / trimming system will be built as an implementable station that will demonstrate the capability and benefits to panel insert fit-up for as many plate sizes and weld profiles as possible. The results of the project are targeted to be integrated into DDG 117 panel lines at Ingalls in the first quarter of calendar year 2014.
Naval Surface Warfare Center, Carderock Division
The University of New Orleans / PD Technologies
PMS 400D - DDG 51 Program Office