导流室设计对薄壁铝型材挤压出口速度的影响

采用基于ALE算法的HyperXtrude软件,模拟薄壁铝合金型材挤压模具导流室各种设计的金属流动情况,分析了各设计参数对金属流速的影响规律,并统计挤出型材断面上挤出方向的流速均方差S.D.作为衡量流速均匀程度的指标。分析结果表明,在设计断面不对称、壁厚不等型材模具时,有时需将型材的质心相对于模具的中心做一定距离的调整。型材断面上各处的壁厚差异和局部质心偏离都对流速有影响,但壁厚差异对于流速均匀程度的影响更大。在模具的型腔内添加阻流块结构,流速均匀程度可大为改善。调节阻流块的宽度、高度、形状、位置等参数,能够完全消除流速不均匀,但如果尺寸调整超过最佳点,流速均匀程度将迅速恶化。根据最优模拟结果对应的设计生产模具,并进行挤压实验,所得型材的尺寸质检合格,模具达到"零试模"要求。

Effect of pocket designs on exit velocity during thin-walled aluminium profile extrusion

Various pocket designs during thin-walled aluminium profile extrusion were simulated by HyperXtrude software based on ALE algorithm.Effect of pocket dimensions on exit velocity was analyzed.As a criterion of exit velocity uniformity,the velocity Standard Deviations were calculated.The simulation results show that sometimes the centroid of the profile should move out of the die center when designing the die for the profile with asymmetrical section and non-equal thickness.Both the thickness difference and mass deviation of the profile have great effects on the exit velocity uniformity,but the effect of thickness difference is larger.Using baffle-block in pocket of die,the exit velocity uniformity can be improved greatly.By adjusting the width,height,shape and position of the baffle-blocks,the exit velocity non-uniformity could be eliminated fully.But the dimension adjustment can not exceed the optimum point,otherwise the flow uniformity would deteriorate rapidly.The trial-manufacturing experiment using the die design corresponding to the optimal simulation results was done.The dimensions of the obtained profiles pass the quality inspection and the die reached the standard of zero-trial die.