Distortion analysis of arc shaped workpiece in NC machining

The objective of this study is to simulate and analyze the effect of residual stress on NC machining distortion. NC machining distortion theory is studied by analyzing the typical aircraft arc shaped workpiece. The causes which lead to machining distortion are analyzed. It indicates that induced residual stress developed at the material manufacturing state is the main source of post machining distortion. The direct coupled field analysis is adopted to develop a quenching induced residual stress field in the workpiece. The contacting analysis technique is used to predict the machining residual stresses developing. Square shaped plates with different thickness are selected to simulating the distortion generated by machining induced residual stresses and quenching induced residual stresses after material removal. A comparison of the distortions generated by two kinds of residual stresses is also presented. Several arc shaped workpieces are adopted to establish initial residual stress fields and simulate the distortion in different cutting quantity and cutting sequence. The simulating results are compared with the actual machining data. It presents that both distortion trends are consistent. The validity of the analysis method is verified. Finally, some suggestions and conclusions are proposed.