Development of New T-Bar Production Technology by Tandem Universal Rolling

Application of T-bars in shipbuilding has increased recently. Slim T-bars having a web height of at least twice the flange width are generally required in ships. Because the dimensions of existing hot-rolled T-bars are unsuitable, T-bars fabricated by welding two plates are currently used in shipbuilding. To manufacture slim T-bars by hot rolling, we devised a new T-bar rolling process using two universal mills and an edging mill. The two universal mills have different roll shapes. The horizontal roll width of the first mill is wider than the web height of the T-bar, whereas that of the second mill is narrower than the web height in order to reduce the web height with a vertical roll. Multi-pass rolling experiments with pure lead were performed using the new process, and a T-bar having an excellent cross section was obtained. Finite element analyses of universal rolling were also carried out to investigate the rolling deformation behavior in this process in detail. Following these investigations, a T-bar hot rolling test was carried out at an actual structural steel mill. As a result, steel T-bars with an excellent cross section were successfully produced, and the capability of the new T-bar rolling technology was clearly demonstrated.