基于离散元锥形零件冲击加载的相对密度

Relative density of conical parts under impact loading based on discrete element

不同形状金属粉末制品在高速压制下的压制行为不一致,从而导致其相对密度以及致密均匀性发生改变。粉末制品零件多含有锥角结构,在压制过程中,金属粉末的致密化程度会随锥角角度的不同而发生变化。借助离散元PFC3D探究锥形零件在冲击加载下不同角度的相对密度。结果表明,锥角角度在30°~60°之间,相对密度表现为波动式变化,有着多个波峰波谷,但整体呈上升趋势;锥角角度在45°~60°之间,相对密度在波动式变化中达到最大值;当锥角角度大于60°,相对密度会下降。随摩擦系数增大,相对密度减小的同时对小锥角零件影响加大。综合分析发现,45°与60°锥角总会处于相对密度峰值附近,而其均匀度系数也相对其他角度较小,45°为锥角零件的优秀角度,相对密度高且较为均匀。实验验证了模拟结论的准确性,为锥角零件的最佳压制成型提供理论依据。

Metal powder products with the different shapes have the different pressing behaviors under the high speed pressing,easily leading to the change in relative density and density uniformity.Most of powder products contain the taper angle structure,and the densification degree of metal powders will change with the taper angle in the process of pressing.The relative density of the conical parts at different angles under impact loading was investigated by discrete element software PFC3D in this paper.It is found that,the relative density shows the fluctuating variation with the multiple peaks and troughs when the taper angle is between 30°and 60°,but the overall trend is upward,and the relative density reaches the maximum value in the trough change with the taper angle between 45°and 60°.When the taper angle is greater than 60°,the relative density decreases.With the increase of the friction coefficient,the relative density decreases,and the effect on the small taper angle parts increases.The comprehensive analysis shows that,the taper angles at 45°and 60°are always near the peak relative density,and the uniformity coefficient is smaller than other angles.45°is the excellent angle for the taper angle parts,showing the higher relative density and uniformity.The experimental results verify the accuracy of the simulation,providing the theoretical basis for the optimal pressing of conical parts.