2012 年 53 巻 620 号 p. 842-846
Products formed using a conventional cold-roll forming machine have cross-sectional profiles constrained to a single width along the longitudinal axis. Products with cross-sectional profiles varying in width in the longitudinal direction, namely, flexible cross sections, cannot be formed using a conventional cold-roll forming machine. In recent years, research and development of a flexible cold roll forming machine controlled by a Progressive Logic Controller (PLC) Unit to form products with flexible cross sections has been carried out in Japan and Europe. In 2011, we presented a forming method for several flexible channel sections and shape defects such as swell distortion, and edge buckling occurred during forming with this machine. In this study, the deformation process of strips in forming a flexible channel section with different widths using a four tandem flexible cold roll forming machine has been experimentally investigated from the relationship between the shape of blank sheets and the strain produced during passage through rolls. A flexible channel section is formed from a blank steel sheet of 0.5 mm thickness with the flexible edge lines. Moreover, the distribution of membrane strains and principal strains occurring at the flange and the web part during the forming of the flexible product are measured using a strain gauge. From these measurements, the mechanism of the occurrence of the swell distortion is clarified.