薄壁小弯曲弯头弹性介质挤胀成形实验研究

Experimental research on extruding-bulging of thin-walled elbow with small bending radius and elastic medium

采用弹性填料作为传力介质对薄壁小弯曲弯头进行挤胀成形,研究了薄壁小弯曲弯头弹性介质挤胀成形机理和主要影响因素,分析了弹性介质下的薄壁小弯曲弯头挤胀成形过程和壁厚分布规律。结果表明:弹性介质在冲头轴向推力与球形芯轴反推力的双向挤压下发生弹性变形并形成连续的弹性体以产生胀力,弯曲时将管坯紧贴于凹模,同时推动管坯沿凹模型腔变形流动;此外,球形芯轴的进给量是弹性介质挤胀成形工艺的关键,在进给量不足时使成形件出现截面畸变及出口端塌陷变形等缺陷;以管径Φ32 mm×1 mm的LF2M铝合金弯头成形为例,球形芯轴的进给量控制在75°时,成形件整体壁厚分布相对均匀,外侧最大壁厚减薄率为16%。

The extruding -bulging of thin-walled elbow with small bending radius by the elastic filling used as medium was conducted, its deformation mechanism and key factors were studied, and the forming process and wall thickness distribution were analyzed. The results show that the elastic deformation and a continuous elastomer are formed by the punch axial and spherical core shaft reverse thrust press to produce expansion force, which makes the tube blank close to the die in the bending and pushes the deformation to flow along the die. In addition, the feeding value of the spherical core shaft is the key parameter for the extruding-bulging with the elastic medium. When it is insufficient, the cross section distortion and the collapse of the exit end are appeared easily. For the push bending of aluminum alloy tube LF2M with Ф32 mm × 1 mm, the wall thickness distribution of the formed parts is relatively uniform, and the maximum thinning rate of lateral wall thickness is up to 16% with the feeding value controlled within 75°.