李峰
,
苑世剑
,
何祝斌
材料科学与工艺
doi:10.3969/j.issn.1005-0299.2007.01.004
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.
关键词:
挤压
,
金属流动
,
导流角
,
应力状态
,
缺陷
李峰
,
林俊峰
,
刘晓晶
材料科学与工艺
针对平模挤压时常因金属流速不均匀而易产生缺陷,本文采用了带导流角结构的芯模进行挤压研究.通过数值模拟和实验,深入分析了挤压过程中金属变形流动行为的机理,结果表明:带导流角芯模挤压时筒底不出现分流的现象,"死区"显著地缩小;处于塑性区内材料的应变类型由三种变为均一的拉伸类,显著地提高了金属变形流动的均匀性,利于金属的挤出成形及制品质量的提高.
关键词:
导流角
,
挤压
,
应变类型
,
缺陷
Shijian YUAN
材料科学技术（英）
To reduce defects, such as the shrinkage cavity and the surface cracks caused by non-homogeneous metal flow in extrusion process, an extrusion method was proposed by using a die with the guiding angle. Numerical simulation and experiment were conducted to investigate the metal flow in this extrusion process. It is shown that the stress state at the bottom of the die is changed. The tendency to generate the dead zone is decreased by employing the guiding angle at the die entrance. The shrinkage cavity is reduced because the non-homogeneous metal flow at the final stage of extrusion is improved. The axial stress is decreased greatly so that the surface cracks caused by additional stress are avoided.
关键词:
Guiding angle
,
挤压
,
金属流动
,
缺陷
