Influence of material strength distribution along thickness on three-roller edge pre-bending of thick plate

Three-roller edge pre-bending of thick plate is affected by non-uniform material strength distribution along the thickness introduced by multi-pass roll forming and heat treatment. Hot-rolled Q235 plates with thickness of 100 mm and 200 mm were investigated by tensile testing of round bars from equal spaced multi-positions along the thickness. The material stress-strain curves of tensile bars were achieved by tensile testing on WAW-E100 machine at a strain rate of 3.0 × 10-5 s-1. The stress-strain relationship of the material considering the non-uniform distribution was obtained. Three-roller edge pre-bending process of thick plate on CCDW11XNC-300420×2500 mm heavy machine with bottom rollers horizontally adjustable was analyzed and an edge pre bending model was developed. Numerical results by this model show that a strength variation of 0~20% along thickness could result in top roller force variation of 0~13%, little increase in springback ratio, and no effect on pre bending angle before unloading. ©, 2015, Editorial Board of Jilin University. All right reserved.