Flange width alteration in universal rolling for production of T-bars with diverse section sizes

摘要

In order to produce T-bars with dimensions suitable for ships, a new T-bar rolling technology employing universal and edger mills is being developed. T-bars with various section sizes are required in ships. Although the new process makes it possible to manufacture T-bars with different thicknesses with the same rolls, individual rolls must be prepared for each outer dimension (web height or flange width). In the case of different flange widths, rolls suitable for each product flange width are necessary for both the breakdown mill and the edger mill. In order to use the same breakdown rolls for T-bars with different flange widths, a method which makes it possible to change the flange width by more than 25 mm in universal rolling was investigated. In T-bar universal rolling, larger flange thickness reduction relative to web thickness reduction causes larger flange spread. This large flange spread should make it possible to produce T-bars having different flange widths with the same breakdown rolls. A series of laboratory rolling experiments was carried out to demonstrate this idea. The model scale was 1/5, and pure lead was used as the model material. Thick pure lead T-section bars suitable for products with a flange width of 100 mm were rolled with a model universal mill. Two draft schedules were examined for the two product flange widths of 125 and 150 mm. As a result, the flange widths of the rolled pure lead T-bars satisfied the target flange widths in 5 to 7 passes. The results of this research demonstrated the possibility of flange width control in universal rolling with the aim of realizing common use of breakdown rolls with different flange widths.