采用三点弯曲JCO成形方法制造大型直缝焊管的技术关键是板坯每道次弯曲角的弹复控制，其成形角的精度直接制约着成形管坯的椭圆度，针对管线钢材料的特点，采用双线性硬化材料模型，基于小变形假设，建立了每道次弯曲成形及弹复计算模型，得到了对应任一凸模行程处板料中性层上任一质点卸载前后的转角和挠度数学表达式，理论和实验数据均表明，弯曲角和成形角之间非常接近线性关系，验证了理论解析的正确性。%The key of technologies for manufacturing large-diameter straight seam submerged arc weld (LSAW) pipes with three-point bending JCO forming is the controlling of springback amount of bending angle in each bending step, and the precision of the forming angle directly determines the eUipticity of the pipes. Aiming at the characteristics of pipeline steel, using the bilinear hardening material model, and base on small deformation theory,the analytical model of forming and springback prediction in each bending step is constructed. The equations for the rotation angle and bending deflection of each point in neutral surface for any punch displacements are derived. Theoretical and experimental data indicate that it very closes to linear relationship between the bending angle and forming angle.and verify that the theoretical analysis is correct.
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