Effect of prestressed ultrasonic peen forming parameters on bending curvature and spherical deformation of plate

预应力超声喷丸参数对板材弯曲曲率及球面变形的影响（英文）

The elastic prestressed ultrasonic peen forming(UPF)was adopted in order to solve problems of insufficient bending deformation and large spherical deformation of plate during free UPF.The theoretical analysis of prestressed UPF and the influence of elastic prebending moment on deformation were analyzed.Spherical deformation coefficient was defined to quantificationally describe the spherical deformation.Experiments were conducted to compare the differences between free UPF and prestressed UPF processes and the effects of processing parameters on bending curvature and spherical deformation coefficient were studied.The results show that peening trajectory in chordwise direction is beneficial to enlarging spanwise bending deformation and decreasing spherical deformation coefficient.Large prebending curvature is helpful to increase spanwise bending deformation and decrease chordwise deformation,thereby obviously decreasing spherical deformation coefficient.Large spanwise deformation can be obtained under large firing pin velocity,small plate thickness and small offset distance.Large firing pin velocity plays a positive role in decreasing spherical deformation,while plate thickness and offset distance have little effect on it.Above all,prebending curvature and peening trajectory are the most important factors during prestressed UPF process.This study provides guidance for parameters optimization of prestressed UPF for wing plate with large thickness.

采用弹性预应力超声喷丸成形技术解决自由超声喷丸成形中板材弯曲变形不充分及出现大球面变形的问题。通过对弹性预应力超声喷丸成形过程进行理论分析,研究弹性预弯力矩对弯曲变形的影响。为了定量描述喷丸过程中球面变形程度,定义球面变形系数。开展自由喷丸和弹性预应力喷丸实验,分析两种喷丸方式的区别,并研究喷丸成形参数对板材成形曲率及球面变形系数的影响。结果表明,弦向喷丸轨迹有利于提高板材展向弯曲变形、同时减小球面变形系数。大预弯曲率能增大展向弯曲变形,同时减小弦向变形,从而显著减小球面变形系数。大撞针速度、小板厚及小偏置距离均有利于提高展向弯曲变形;在预应力喷丸成形过程中,大撞针速度有利于减小球面变形,而板厚及偏置距离的变化对球面变形系数影响很小。综上,在预应力喷丸成形过程中,预弯曲率及喷丸轨迹是最重要的两个影响参数。本研究可为大厚度翼板类零件的预应力超声喷丸成形过程参数优化提供指导。