镦粗过程中的锻件缩孔闭合顺序

Closure order of shrinkage in the upsetting forging

锻件镦粗过程中,宏观模型与微观模型具有相同的变形过程,即相同压下步数下所用的时间相等。通过测量代表性特征体中所含缩孔闭合时相对应的宏观模型中的压下量,来确定这些特征点区域内缩孔的闭合顺序。在Deform-2D软件中建立平面镦粗模型,由于工件具有对称性,在工件上选取有限个特征点,通过改变温度、应变速率及缩孔尺寸大小来进行模拟,选取合适的模型压下量,得知各特征点的闭合顺序受温度和缺陷尺寸的影响比较小,而应变速率的变化将引起特征点闭合顺序发生显著的变化。与实际对比,相同条件下的锻件内部变形区域基本一致,验证了不同变形环境下的不同变形区域内所含缩孔的闭合顺序。

The macro model and micro model are of the same deformation process in the upsetting process,namely,the time spent on the same amount of upsetting is equal.Then,the amount of upsetting in the macroscopic model corresponding the shrinkage closure in the representative feature body was used to determine the closure order of shrinkage in the region of these feature points.The upsetting model was established by the software DEFORM-2D.Due to the workpiece with symmetry,the limited feature points on the workpiece were selected,so the finite element simulation was carried out by changing the temperature,strain rate and shrinkage size.Furthermore,the appropriate amount of upsetting was selected,and it was found that the influence of temperature and shrinkage size on the closure order of each feature point was relatively small,but the variation of strain rate made the feature point closure order change significantly.In comparison with the actual condition,the deformation zone was basically identical under the same condition.Thus,the closed order of shrinkage in different deformation zones under various forming environment was verified.