超声喷丸作为一种新型的板料成形技术,具有易操作,能耗少及优良成形性能等优点,广泛应用于板料成形中.但自由状态下,超声喷丸成形也易发生球面变形,因而提出了弹性预应力超声喷丸成形方法,以2024-T351铝合金壁板为研究对象,分析预弯力矩大小、成形轨迹和壁板厚度对成形曲率半径及成形性能的影响.试验中通过控制壁板展向的弯曲曲率来实现弹性预弯.结果表明:预应力超声喷丸能够大幅度减小壁板展向的成形曲率半径,同时增大弦向成形曲率半径,且随着预弯曲率半径的减小,这种减小和增大的效应随之逐渐增大.此外,与自由状态相比,预应力超声喷丸能够产生幅度和深度更大的残余压应力场,且表面粗糙度并未随着预弯曲率的增大而增加.分析认为,弹性预应力超声波喷丸能够进一步提高受喷材料的成形曲率并在一定程度上减小球面变形趋势,对大变形大厚度的单曲率零件成形具有重要的意义.
Ultrasonic shot peening is a new type of forming technology with many merits such as operability,low energy consumption and good comprehensive performance,which is widely used in sheet metal forming process.The elastic prestressed ultrasonic peen forming method was put forward due to the spherical deformation during ultrasonic peen forming process in the free state.The effects of prestressed moment,forming trajectory and plate thickness on forming curvature radius and forming performance were investigated for 2024-T351 aluminum alloy wall panel.The elastic prebending curvature was achieved by controlling the prebending curvature through the span wise direction of the plate.Results show that prestressed ultrasonic peen forming can significantly reduce the curvature radius through the span wise direction and increase the curvature radius through the chord wise direction.Meanwhile,the variation range is increased with descending prebending curvature radius.Larger residual stress and bigger influence depth of residual stress appear in prestressed ultrasonic peen forming compared with that of the free state.The surface roughness increases with ascending prebending curvature.Therefore,the elastic prestressed ultrasonic peen forming can further improve the forming curvature and decrease the spherical deformation tendency to a certain extent,which has a great significance to the forming process of plate with the large deformation,large thickness and single curvature.
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