Surface deformation errors and self-adaptive compensation for microstructured surface generation of titanium alloys

Abstract

In diamond servo cutting (DSC) of microstructured surfaces, the oscillated cutting motion inevitably cause non-uniform surface deformation errors. Although static and dynamic geometric errors for DSC have been studied, few studies focus on the prediction and compensation strategies of the surface deformation errors for microstructured surface generation. This study proposes an microstructured surface generation model of titanium alloys by considering the dynamic cutting forces, material microstructure evolution, thermal-mechanical coupling effect and subsurface stress-strain distribution. Harmonic microstructured surfaces are fabricated to characterize the non-uniform surface deformation errors as well as to validate the proposed model. The results show that the proposed model can accurately simulate the variation of surface plastic and elastic deformation errors as a function of undeformed chip thickness and cutting direction. Compared with the downslope cutting direction, the machined surface in upslope direction is subjected to greater plastic strain and plastic deformation errors even at the same depth of cut, due to cutting direction effect. To compensate surface deformation errors, a cooperative servo cutting (CSC) strategy is proposed by incorporating a self-adaptive fast tool servo into conventional servo cutting. The instantaneous compensation motion of CSC is jointly determined by the curvature radius deviation, instantaneous cutting depth and cutting direction. The experimental results show that CSC can make the error distribution more uniform, and greatly decrease the peak-to-valley surface deformation errors from 1.29 to 0.24 μm for different microstructured surfaces.