薄壁扇形筋板反挤压成形应力转移法

Stress transfer method in backward extrusion forming of thin-walled fan-shaped rib

对6063铝合金复杂腔体零件中薄壁扇形筋板反挤压成形过程进行了模拟分析,发现扇形筋板的两端过渡圆角处易产生应力集中,从而导致开裂。增大凸模圆角可以有效降低筋板内的拉应力峰值,并使拉应力均匀分布,但该方法不符合现阶段工艺要求。因此,基于筋板中部切口应力集中现象提出了一种应力转移法,通过该方法改变了筋板内拉应力的分布形态,消除了圆角处由于应力集中而引起的挤压成形缺陷问题。采用单切口和双切口方法均可以大幅降低筋板过渡圆角处的拉应力,解决了开裂问题,实际生产效果与模拟结果具有较好一致性。

The backward extrusion process of thin-walled fan-shaped rib of 6063 aluminum alloy parts with complex cavity was simulated and analyzed.It is found that stress concentration is easy to occur at both ends of the transition rounded fillets of fan-shaped rib,which leads to cracking.Increasing the punch fillet can effectively decrease the peak value of tensile stress in the ribs,and make the tensile stress distribute evenly,but it does not fit the current technological requirements.Therefore,a stress transfer method was proposed based on the phenomenon of the stress concentration in the center incision of ribs.The distribution pattern of tensile stress in the ribs was changed and the extrusion defects caused by the stress concentration at the rounded fillets were eliminated by this method.The tensile stress at the transition rounded fillets of the ribs can be significantly reduced by both single incision and double incisions methods,which solves the cracking problem.The actual production results are in good agreement with simulation results.