半固态挤压扩展成形过程金属流动规律的有限元分析

FEM Analysis of Metal Flow Behavior During Continuous Extruding/Extending Forming in Semi-Solid State

利用有限元法对半固态连续挤压扩展成形过程中扩展腔内的金属流动规律进行模拟,得到了不同模具设计参数下的金属流动规律·结果表明,高固相率半固态金属浆料以层流方式填充模具,扩展腔内半固态金属浆料流动速度从扩展腔中心区域向两边侧壁逐渐减小·随着扩展角、模具台阶长度的增大,模具出口横断面上金属流动速度趋于更加均匀,随着模具定径带宽度增大,金属流动不均匀性增加,同时台阶太长,模具扩展腔两侧会出现金属流动的死区或涡流·在合理的模具设计条件下,可以实现半固态连续挤压扩展成形·

How the metal flows in the extending cavity during continuous extruding/extending forming in semi-solid state was simulated by finite element method (FEM) to investigate the metal flow behavior in the moulds designed with different parameters. The calculated results indicate that the highly solidifiable semi-solid alloy fills in the extending mould in form of laminar flow and the flow velocity decreases gradually from the center to all sides in mould. The flow velocity at the outlet of mould becomes more even with increasing extending angle or step length. However, The flow velocity at the outlet of mould becomes more uneven with increasing outlet width. There is a dead zone or vortex flow on both sides of mould when the step is too long. It is proved that the continuous extruding/extending forming can be implemented only if the mould is designed rationally.