Ti6Al4V零件铣削加工表面等效残余应力与作用深度的测量及其有限元分析

The measurement of equivalent surface residual stresses and the effective depth generated by milling Ti6Al4V parts and its FE

摘要:

金属零件在切削加工后，其被加工表面会形成一残余应力层，其所引起零件的变形是影响精密弱刚性零件精度的重要的因素。为了预测Ti6Al4V零件因铣削加工表面残余应力而引起的变形，本文介绍一种测量表面等效残余应力及其作用深度的方法而达到此目的。通过对被加工面的对面进行两次腐蚀去除材料的操作使得零件的厚度和中性层的位置发生变化，测量此过程中零件挠度和表面应变的变化，进而计算得铣削加工引起的零件表面等效残余应力及其作用深度值。通过有限元分析验证该方法得到的结果，发现有限元计算得到的零件挠度和应变的变化与实际测量值非常吻合，因此可以断定该方法得到的结果是正确的，其可以正确评估铣削加工引起的表面残余应力性质和大小并能准确预测零件铣削加工后因表面残余应力而引起的工件的变形量，从而可以预测零件是否满足精度要求。

Abstract:

After machining metallic parts, there will be residual stresses generated by machining in surface layers of the machined parts, the deformations caused by surface residual stresses have a strong effect to the parts accuracy. In order to predict the deformations caused by surface residual stresses generated by milling Ti6Al4V parts, this paper presents a method for measuring the equivalent surface residual stresses and the effective depth to solve this problem. The material in the surface opposite to the machined surface were removed twice, the depth and the neutral layer of the workpiece were changed, the change of the bending deflections and the strains measured from the machined surface were measured after that, and then the equivalent surface residual stresses and the effective depth can be calculated out. FEA (finite element analysis) was used to validated the correctness of this method, the results calculated by FEA correspond well to those measured in the experiments, so it can be concluded that the results got from the method proposed in this paper are correct, they can be used to evaluated the surface residual stresses generated by milling and predicted the deformations caused by surface residual stresses, as to predict if the parts accuracy can meet the requirement.