材料期刊网

为了解镁合金连续挤压扩展流动规律与工艺条件的关系，基于 DEFORM?3D 软件，建立镁合金的刚塑性有限元模型，通过数值模拟分析连续挤压过程坯料沿纵向对称面上的速度演变规律，探讨挤压轮转速对坯料各层面速度分布的影响机制。结果表明，在连续挤压过程中，金属流动速度在各变形区呈不同变化趋势。轮槽区的速度呈现由轮槽底面向封料面逐渐降低的分布形态；直角弯曲区的流道底部速度最高；扩展区由中心向两侧流动速度逐渐减小；在阻流区和模具区，流动速度的差别减小。随着挤压轮转速的增大，直角弯曲区和扩展区各层面金属的速度差值增大，流动的不均匀程度增加。连续挤压过程中金属的这种流动分布特点缘于轮槽面的摩擦驱动力与型腔壁摩擦阻力的相互作用。

For understanding the relationship between the expansion flow and process conditions, based on the DEFORM-3D software, the model of rigid-plastic FEM was established. The velocity evolution rule on the longitudinal symmetry plane was analyzed during the forming process through numerical simulation. The effect of extrusion wheel velocity on the metal velocity distributions of all surfaces was investigated. The results show that the metal velocity presents various changing forms in different deformation regions. In the groove region, the velocity gradually decreases from groove bottom to enclosing surface. In the rectangular bending region, the velocity at the channel bottom is the highest. In the expansion region, the velocity gradually decreases from the center to the two sides. In the choked flow and die regions, the flow velocity differences are smaller than those of other regions. With the increase of wheel velocities, in the rectangular bending and expansion regions, the differences of the highest and lowest velocities and the non-uniformity of flow increase for all surfaces. The flow distribution characteristics of the continuous extrusion are induced by the interaction between the driving force of the wheel groove and the friction resistance of the cavity wall.