Development of Computer-Aided Process Planning System for Plate Bending by Line Heating (Report 2)—Practice for Plate Bending in Shipyard Viewed from Aspect of Inherent Strain

In the plate bending process by line heating, the decisions as to which part of the plate should be heated and in which direction are usually made by skillful workers. However, the number of skilled workers is declining rapidly and in recent years this has become a serious problem in shipyards. To solve the problem, the authors in an earlier report proposed a method to make the decisions based on theoretical analyses focused on inherent strain. The potential usefulness of the method was demonstrated through example problems dealing with mathematical ideal geometry. In the present report, a comparison is made between theoretical predictions and actual shipyard practice in forming curved members of a ship hull, and an attempt is made to visualize the knowledge of skilled workers, which heretofore was invisible, using computer graphic images showing inherent strain. Further, it is demonstrated that the same idea can be applied not only to make decisions on the line heating process but also to design the total plate bending process, including decisions on using the bending roller and the press machine.