Effect of Bend Angle and Web Width on Deformation Behavior of Sheet Metal in Roll Forming of Hat Section

摘要

The deformation features of sheet metals (carbon steel, 0.55 mm thickness, 144.3 approx 393 .9 mm width) formed into hat sections (48.8 approx 298.4 mm web width (2b_1), 24.3mm flange width, 15 deg approx 30 deg bend angle (theta) at corners located on both sides of the web (bent corner-1)) by a single stand mill with grooved rolls are discussed based on results obtained by elastoplastic FEM. There is a tendency just after roll kiss that the minimum value of dimensionless longitudinal membrane stress on the web ((sigma_(ml)/sigma_e)_(min), <0, sigma_e: initial stress yield), transverse position where (sigma_(ml)/sigma_e)_(min) generates ((b/b_1)_p, b: transverse distance from the web center), longitudinal membrane strain at bent corner-1 (epsilon_(ml)(b/b = 1.0), <0) and mean value of dimensionless longitudinal membrane stress on the web ((sigma_(ml)/sigma_e)_(ave), <0) decrease with the increase in bend angle, and increase with the increase in web width except (b/b_1)_p=0, namely, b_1 = 24.4mm and theta =30 deg. However, the critical buckling stress of the web (<0) increases more than (sigma_(ml)/sigma_e)_(ave) with the increase in web width.