摘要
为研究粉末在高速压实下模壁摩擦因数的影响,分别选择Cu、Fe作为压制粉末,在MARC中建立微观的粉末模型,视冲头为刚体以计算得到的加载速度模拟压制粉末体。通过设定不同的边界摩擦因素,发现与传统静力压制相比,电磁脉冲高速压制时并非模壁的摩擦因数越小,压制件的密度越均匀,当速度超过60 m/s时,由于应力波叠加的作用,使得摩擦因数小于一定值以后,铜粉压坯在压制中期从下端先开始压实,最终导致粉末坯体的密度由下往上递减。分析发现当金属粉末颗粒密度大于4 g/cm3,同时应变敏感性指数C小于0.09时会出现最佳摩擦因数使得压制的毛坯密度均匀性最好,同时最佳摩擦因数在4~9 g/cm3密度范围内与密度成正比,在0.005~0.01的应变敏感性指数范围内与应变敏感性指数成反比。
In order to research the effect of friction coefficient of die wall under the high-speed compacted powder, Cu and Fe were selected as compacted powder, respectively. Microscopic model of powder was built in MARC, and punch was viewed as rigid body to calculate the simulated compacted powder body. By setting different boundary friction factors and comparing with the conventional static pressing, it＇ s found that it＇ s not that the smaller friction coefficient , the more uniform pressed part . When the speed exceeds 60 m/s, due to effect of stress wave superposition,density of copper powder compact decrease progressively bottom up when friction coefficient is less than a certain value. Analysis shows that optimum friction coefficient made the density of pressed compact uniform appears when the density of metal powder particles is larger than 4 g/cm3 and the strain sensitivity index C is less than 0.09 Meanwhile, optimum friction coefficient is proportional to density ranging from 4 to 9 g/cm3, and is inverse proportional to strain sensitivity index ranging from 0. 005 to 0.01.
出处
《粉末冶金技术》
CAS
CSCD
北大核心
2014年第6期442-447,共6页
Powder Metallurgy Technology
基金
国家自然科学基金资助项目(11372148)
