A novel analytical model for predicting the thin-walled workpiece deformation considering the effect of residual stress accumulation and redistribution in layer by layer milling

Abstract

In aviation industry, aluminum alloy is widely applied in the thin-walled workpieces owing to its high specific strength, low density and good machinability. For thin-walled workpiece, machining deformation is a very serious challenge, and with material removal in milling, the initial and milling residual stresses inside the workpiece are continuously released and redistributed, which cause the thin-walled workpiece deformation and deteriorates workpiece dimensional accuracy and milling quality. To reveal the influence of residual stress on workpiece deformation, a novel analytical model for predicting the thin-walled workpiece deformation considering the impact of residual stress accumulation and redistribution in layer by layer milling is proposed in the paper. In this process, the distribution mechanism of thin-walled workpiece initial residual stress is explored furtherly by analyzing the force state of workpiece, and the forces and the moment are obtained on the to be machined layer and the machined layer under the layer by layer conditions. Then, the residual stress generation mechanism induced by thermal stress and mechanical stress are researched, and the residual stress distributed model is founded. Subsequently, the coupled accumulation mechanism of initial and milling residual stress are determined, which directly affects the workpiece deformation. Next, an overall thin-walled workpiece deformation prediction model induced by residual stress in layer by layer milling is proposed. Finally, several experimental tests are carried out to validated the effectiveness and feasibility of the proposed model, and the experimental results manifest that the calculated workpiece deformation proximately align with that measured, the minimum and maximum errors are 1.3 % and 13 %, respectively, and the whole average error is 9.76 %.