压坯高径比对粉末冶金制品性能影响的有限元模拟

FE Simulation of Influence of Height-diameter Ratio on Powder Metallurgic Product Properties

利用MSC/MARC有限元分析软件对金属粉末温压过程进行了模拟分析。采用基于更新拉格朗日方法的热—机耦合分析方法分析了不同压坯高径比对压坯性能(相对密度、等效应力)的影响规律。结果显示:在相同的侧压系数下,不同的初始松装高度与压坯直径对压坯相对密度分布影响不大,其分布规律基本一致;随着侧压系数的增大,压坯相对密度分布愈加不均匀,差值越来越大,低密度区域逐渐扩大。对压坯等效应力分布状况进行了研究,结果表明:侧压系数的分布呈X形,与镦粗变形相似,在X形的空心区域等效应力较低,是"摩擦死区",在X形的线区域等效应力较大,是"易变形区";随着侧压系数的增大,摩擦死区逐渐增大,同时随着初始松装高度的增大,压坯等效应力增大。

The process of the metal powder warm compaction process was simulated by the finite element analysis（FEA） software,MSC/MARC. The simulation applied thermal mechanically coupled analysis,which was based on the updated Lagrangian Method to study the influence rules of different height-diameter ratio on the properties （relative density, equivalent stress） of green. The results indicate that the influence of two factors i. e. initially loose height and green diameter on the relative density distribution is not large with the same side pressing parameter, and the rules of its distribution are basically the same. With the increasing of side pressing parameter, the distribution of green relative density is not gradually uniformity,deviation value is gradually large, and area of low density gradually widen. The study of distribution of green equivalent stress was made, the distribution presents ＇X＇ shape,which is same as the deformation of upset forging. Equivalent stress in the hollow area of ＇X＇ is relatively lower and this is ＇friction dying area＇, equivalent stress in the area of ＇X＇ lines is relatively larger and is ＇easily deformable area＇. With increasing of side pressing parameter, ＇friction dying area＇ gradually widen. And equivalent stress of green increases with increasing of initially loose height.