超声辅助铍青铜箔材微弯曲变形规律及机理研究

The springback of the micro-bending can cause the dimension accuracy of micro component not to meet the technical requirements. For this purpose, the ultrasonic assisted micro bending technology of beryllium bronze foil was presented, which might restrain the springback of micro bending, promote the uniformity of deformation, and achieve the dimension accuracy. In this research, the ultrasonic excitation hardware and software system was first built, and the design and evaluation of ultrasonic excitation mode was discussed. The effect of ultrasonic excitation parameters and grain size were discussed on mechanical performance of foil, and the material constitutive model was proposed. And then the influence of ultrasonic excitation parameters and grain size were discussed on dimension accuracy and grain size of micro bending component, and the response surface model was developed to obtain the optimal process parameters and give a stability control method. The macroscopic plastic flow characteristics, grain orientation and grain deformation behavior in different plastic deformation zone were observed, and the field distribution characteristics of ultrasonic power was given. The deformation mechanism of uniformity according to ultrasonic propagation characteristics was finally revealed.

箔材微弯曲成形回弹导致高精密微型构件尺寸精度不符合技术要求。为此，提出超声辅助铍青铜箔材微弯曲成形方法，有效抑制微弯曲回弹，改善局部非均匀塑性变形对尺寸精度的影响。本研究首先搭建超声激励的硬件和软件系统，明确超声激励模式的设计与评价方法；分析超声激励参数和原始晶粒尺寸对金属箔板力学性能的影响规律，建立金属箔板的本构模型；分析超声激励参数、原始材料晶粒尺寸对箔板微弯曲件尺寸精度和表面质量影响规律，建立尺寸精度和不同变形区表面质量同超声激励参数和原始晶粒尺寸之间响应面模型，获取优化工艺路线，给出微型构件尺寸精度稳定控制方法；研究超声辅助条件下箔材宏观塑性流动特点和不同塑性变形区表面层及内部有限晶粒取向演变行为、声场分布特点以及超声激励参数与应变速率的协调关系，揭示超声波激励对箔材变形均匀性的作用机制。

明确了超声激励模式的设计与评价方法，实现了超声激励参数的选择，并构建了超声辅助箔板的材料本构模型；获取了超声辅助箔板微弯曲成形过程回弹量和表面粗糙度变化规律，建立了尺寸精度和表面质量同超声激励参数和原始晶粒尺寸之间映射关系，给出了箔材微弯曲件尺寸精度控制和剧烈变形区表面质量控制方法；给出了超声辅助条件下箔材表层及内部塑性流动特点和不同塑性变形区表面层及内部有限晶粒取向演变行为、声场分布特点以及超声激励参数与应变速率的协调关系，揭示了超声波激励对箔材变形均匀性的作用机制。