Since the universal jig surface tables are linked to the JIG system, the height of the pin jigs that support a curved block can be set quickly by means of numerical control based on the simulated data.
As shown in Figure 2, the gantry type robot performs single-layer welding automatically on curved shell plates from one-side. This robot is unique： it carries out one-side welding without monitoring as it detects the weld line and joint inclination by means of two kinds of sensors and as it automatically selects the optimum welding conditions from among those programmed into its control unit beforehand. This robot, developed by Hitachi Zosen jointly with Nippon Steel Welding Products & Engineering Co., Ltd., employs new technology that makes use of a two electrode carbon dioxide arc welding method for a welding speed twice that of conventional automatic submerged arc welding equipment. In this method, one-side welding, which is difficult for curved shell plates, is carried out by fusing the tack-welded beads in the groove as shown in Figure 3. Ariake Works succeeded in pioneering the practical use of these robots. Fillet welding on longitudinal members is done automatically by a 12-electrode line welder.
Automatic welding of curved blocks for hulls has been considered so difficult that it is said, "One who masters curved block welding masters shipbuilding." Aiming to achieve the highest level of production technology in shipbuilding, Hitachi Zosen Ariake Works, as it rises to the challenge of solving this difficult problem, is continuously developing optimum production system for fully automated curbed block assembly lines. Automation of the next stage, welding of trans-verse members, will not be long in coming.
