基于能量理论的航空整体结构件滚压变形校正载荷预测方法

摘要

航空整体结构件在数控加工过程中,由于多种因素耦合作用影响,普遍存在不同程度、不同形式的加工变形问题.滚压校正是实现大长宽比薄壁结构件变形校正的有效手段,且在获得工件尺寸精度的同时,引入压应力,提高工件使用寿命.目前,滚压变形校正多依赖于工人经验和试错法,缺乏校正载荷的准确预测方法,质量稳定性差.为此,基于能量理论,在分析梁类零件校正过程能量平衡要求的基础上,结合等效截面法和弯曲应变能法,分别对变形工件的弯曲应变能和滚压做功进行计算,进而建立工件变形量与校正载荷间的数学模型,实现滚压变形校正载荷预测.进一步,为实现校正载荷准确性的快速评价,采用直接应力法建立了加工变形-滚压校正协同仿真环境,实现了梁类航空整体结构件滚压变形校正的快速等效模拟.最后,以三隔框结构件为例进行了有限元仿真和试验验证,直接应力法仿真分析获得的变形消除率为94.5％,试验获得的单次滚压变形消除率达到82.0％,滚压区域表面由铣削拉应力转变为滚压压应力,校正效果符合预期.%Monolithic aeronautical components have varying degrees and forms of machining deformation due to the coupling effect of various factors in Numerical Control (NC) machining.Rolling operation is an effective means to correct distortion of large aspect ratio thin-walled structures,and compressive stress is introduced to improve the service life and obtain the dimensional accuracy of the workpiece.At present,rolling correction depends mainly on the trial and error method based on workers' experience,and lack of accurate prediction method for the corrected load leads to poor quality stability.In this paper,the requirement for energy balance of a beam structure is analyzed.The equivalent section method and the bending strain energy method are used to calculate the bending strain energy and the rolling introduced energy,respectively.Then,a mathematical model for workpiece distortion and correction load is established to predict the correction load.To achieve rapid evaluation of accuracy of the correction load,the collaborative simulation environment of machining distortion-rolling correction is established by the direct stress method to realize fast-equivalent simulation of deformation of monolithic aeronautical components.The three-frame integral structure is used as an example to verify that the distortion elimination rate obtained by the simulation with the direct stress method is 94.5 ％.The experimental results show that the distortion elimination rate of single rolling is 82.0％,and the surface of the rolling area is changed from milling tensile stress to rolling compressive stress.The correction effect is in line with expectations.