Design of the Intersector Welding Robot for vacuum vessel assembly and maintenance

Next Step Fusion Devices require on-site (field weld) joining of sectors of the thick-walled Vacuum vessel for structural and vacuum integrity. EFDA ( European Fusion Development Agreement) is supporting an R&D programme to in vestigate processes for assembly of the vacuum vessel and to carry out cutt ing, re-welding and inspection for remote sector replacement, forming part of the overall VV/blanket research effort. In order to direct the process e nd-effecters along the field joint zone, a track-mounted Intersector Weldin g Robot (IWR) on a mock-up of a region of the vacuum Vessel has been design ed and is described in this paper. A rail-mounted hexapod type robot offers six axes of motion over a limited work envelope with high payload to robot weight ratio. A solution to the production of reduced pressure local vacuu m is the installation of short, lightweight segments bolted to each other a nd the vessel wall. The Various process heads can be mounted using end-effe cters of special design. To minimise the supply and interface problems for the IWR prototype, its motion control and electronic systems will be embedd ed locally. A laser scan with camera forms the on-line seam tracking capabi lity to compensate for rail and seam deviations. (C) 2000 Published by Else vier Science B.V.