铝合金大型复杂薄壁壳体多道次旋压缺陷形成机理

Forming mechanism of defects in spinning of large complicated thin-wall aluminum alloy shells

铝合金大型复杂薄壁壳体旋压是多道次、多参数耦合作用下的复杂非线性过程,该过程中易出现反挤、鼓包、破裂等缺陷。采用实验和有限元模拟相结合的方法,分析这些缺陷的形成机理。结果表明,过大减薄率引起的旋轮前方金属隆起是导致反挤、鼓包、环状剥离及周向开裂的主因,过高的芯模转速会导致周向开裂和鳞状剥离等缺陷。提出了相应的缺陷防止措施,即采用24%以内的减薄率可以避免旋轮前方金属的严重隆起;限制芯模转速过高,以避免周向开裂和鳞状剥离等缺陷的发生。采用这些措施旋制出了合格的铝合金大型复杂薄壁壳体。

The spinning of large complicated thin-wall aluminum alloy shells is a multi-pass complex nonlinear plastic process under the effects of multi-parameters and their interactions.In the progress,defects such as backward extrusion,bulging,rupture are prone to occur.In this study,the forming mechanisms of these defects were investigated by experiments and finite element simulation.The results showed that excessive wall thickness reduction caused the metal bulge before the rollers,which was the main reason for backward extrusion,bulging,ring stripping and rupture.And excessive rotational speed of mandrel caused rupture and fish scale peeling.Moreover,some measures were proposed to avoid these flaws.The wall thickness reduction less than 24% was adopted to avoid the metal bulge before rollers.The rotational speed of mandrel was limited to avoid fish scale peeling and rupture in circumferential direction.Using these measures,qualified large complicated thin-wall aluminum alloy shells were formed.