导流角对挤压变形中金属流动与缺陷的影响

为了减少平模挤压时因金属流动不均匀而产生死区、缩孔及表面裂纹等缺陷,在此采用了一种带导流角结构的芯模用于挤压.用数值模拟对有、无导流角两种形式挤压过程中金属的变形流动行为进行了研究,通过对比分析可知:增加导流角可以改变凹模底角部区域应力分布,减少死区产生的范围;改善了挤压末期筒内等效应变的不均匀程度,使轴心末端不易出现缩孔;使出口处与轴心最远点的应力状态发生改变,轴向拉应力的数值减少了一半,降低了在表面由于附加应力而产生裂纹的可能性.

Effect of guiding angle on metal flow and defects in extrusion deformation

In order to reduce defects, such as the dead zone, the shrinkage cavity and the caused by non-homogeneous metal flow in extrusion process, an extrusion process is proposed surface cracks, by using a die with the guiding angle. Numerical simulation is carried out on the metal flow of extrusion process with and without a guiding angle. It is shown from simulation results that the stress distribution at the lower comer of the bottom die is optimized and the dead zone is decreased as there is the guiding angle. The inhomogeneous equivalent strain is improveds in the container at the final ation of shrinking hole at the end of the axis. The stress is changed, and the axial stress is decreased by half, so stage of extrusion, which reduces possibility of gener- condition of the farthest point from the axis at the exit that the risk in generation of surface cracks caused by additional stress is greatly reduced.