The integration of ultrasonic vibration into sheet forming process can significantly reduce the forming force and bring benefits including the enhancement of surface quality, the enhancement of formability and the reduction of spring-back. However, the influencing mechanisms of the high-frequency vibration on parts properties during the incremental sheet forming (ISF) process are not well known, preventing a more efficient forming system. This paper comprehensively investigates the effects of different process parameters (vibration amplitude, step-down size, rotation speed and forming angle) on the micro-hardness, minimum thickness, forming limit and residual stress of the formed parts. First, a series of truncated pyramids were formed with an experimental platform designed for the ultrasonic-assisted incremental sheet forming. Then, micro-hardness tests, minimum thickness measurements and residual stress tests were performed for the formed parts. The results showed that the surface micro-hardness of the formed part was reduced since the vibration stress induced by the ultrasonic vibration within the material which eliminated the original internal stress. The superimposed ultrasonic vibration can effectively uniform the residual stress and thickness distribution, and improve the forming limit in the case of the small deformation rate. In addition, through the tensile fracture analysis of the formed part, it is shown that the elongation of material is improved and the elastic modulus and hardening index are decreased. The findings of the present work lay the foundation for a better integration of the ultrasonic vibration system into the incremental sheet forming process.

将超声振动整合到板材成形过程中可以显着降低成形力，并带来许多好处，包括提高表面质量，增强可成形性和减少回弹。但是，高频振动对增量板材成形（ISF）过程中零件性能的影响机制尚不为人所知，从而妨碍了更有效的成形系统。本文全面研究了不同工艺参数（振动幅度，台阶尺寸，旋转速度和成形角度）对成形零件的显微硬度，最小厚度，成形极限和残余应力的影响。首先，通过设计用于超声辅助渐进片材成形的实验平台，形成了一系列截顶的金字塔。然后，对成型零件进行了显微硬度测试，最小厚度测量和残余应力测试。结果表明，由于材料内的超声振动引起的振动应力消除了原始内应力，因此降低了成型零件的表面显微硬度。叠加的超声振动可以有效地使残余应力和厚度分布均匀，并在变形率较小的情况下提高成形极限。另外，通过对成形部件进行拉伸断裂分析，表明材料的伸长率得到改善并且弹性模量和硬化指数降低。本工作的发现为将超声振动系统更好地集成到增量板材成形过程中奠定了基础。对成型零件进行最小厚度测量和残余应力测试。结果表明，由于材料内的超声振动引起的振动应力消除了原始内应力，因此降低了成型零件的表面显微硬度。叠加的超声振动可以有效地使残余应力和厚度分布均匀，并在变形率较小的情况下提高成形极限。另外，通过对成形部件进行拉伸断裂分析，表明材料的伸长率得到改善并且弹性模量和硬化指数降低。本工作的发现为将超声振动系统更好地集成到增量板材成形过程中奠定了基础。对成型零件进行最小厚度测量和残余应力测试。结果表明，由于材料内的超声振动引起的振动应力消除了原始内应力，因此降低了成型零件的表面显微硬度。叠加的超声波振动可以有效地使残余应力和厚度分布均匀，并在变形率较小的情况下提高成形极限。另外，通过对成形部件进行拉伸断裂分析，表明材料的伸长率得到改善并且弹性模量和硬化指数降低。本工作的发现为将超声振动系统更好地集成到增量板材成形过程中奠定了基础。