大直径薄壁导管弯曲回弹解析计算

Analysis on Springback of Big Diameter Thin-Wall Tube Bending Forming

以大直径薄壁导管弯曲成形为研究对象,基于塑性力学全量理论,假设弯管过程中各纤维层只存在单轴应变和应力,并假设弯管过程中管件中性层偏移角和楔形角与弯曲角的函数,进而得到弯管过程应变的计算关系式,而后通过应力应变关系得出应力表达式,通过截面应力积分及微分单元力平衡得出管件弯曲部分与模具的接触正应力及摩擦力,通过边界内力积分计算得出外力,通过弯曲段力平衡及能量平衡计算得出偏移角和楔形角函数表达式中的系数,从而计算得出回弹角,并分析了部分工艺参数对回弹的影响规律。

Based on plastic mechanics total strain theory, big diameter thin-walled tube bending forming is researched by assuming that only axial stress and strain in every fiber layer exist during tube bending process. The strain calculation equations of tube bending process are created by assuming the function of neutral layer offset angle and cuneiform angle with the angle coordinate. Then the stresses are gained by the relation of strain and stress, and the contact pressure and friction between die and tube are obtained through the integrating of stress on section and the force equilibrium in differential element. Outside force is calculated through the integrating of inner force on boundary. At last the coefficient of the function of neutral layer offset and cuneiform angle in bending segment are calculated through the force equilibrium equation and energy equilibrium equation. Thereby the springback angle is calculated and the influence law some process parameters to springback is analyzed.