不同成型工艺下钕铁硼模压成型过程的力学行为分析

Mechanical behavior analysis on the compression molding process of NdFeB by different molding technology

为了优化钕铁硼粉末模压成型工艺,通过离散元软件EDEM建立模压成型过程的离散元模型,分析不同成型工艺条件(压制速度和摩擦系数)对压坯力学特征(压制力和压坯内应力)的影响,为优化钕铁硼成型工艺提供理论参考。结果表明:在成型过程中,钕铁硼粉末位置状态基本保持与布粉时一致,只有靠近模冲区域的粉末发生较大位移;压坯成型时会出现应力松弛现象,不同速度压制成型对压制力峰值影响不同,但压制力最终均会收敛至相近的平衡值;添加润滑剂能改善压坯内部受力状态,减小压制力,但是也会减小压坯相对密度;对于大尺寸压坯成型宜采用双向压制方式。

The discrete element model of the compression molding process was established by the EDEM discrete element software to optimize the process of NdFeB powders compression molding.The effects of the different molding conditions(pressing speed and friction coefficient)on the mechanical characteristics of the green pressing(compression force and pressing internal stress)were analyzed to provide the reference for the optimizing of the molding parameters.The results show that,the position of NdFeB powders is the same as that at the time of powder distraction during the molding process,but the powders near the die-stamping area displace greatly.The stress relaxation phenomenon occurs at the molding of green pressing.It is worthy noticing that the pressing speed has the different effects on the peak force of compression,but eventually it will converge to a similar stable value.The addition of lubricant can improve the internal stress state of the green pressing,reduce the compression force,and decrease the relative density of the green pressing.For the large-scale green pressing,the two-directional pressing should be adopted.