Finite-element modeling of static surface errors in the peripheral millingof thin-walled workpieces

The present study develops a finite-element model along with an adequate en d milling cutting-force model to analyze the surface dimensional errors in the peripheral milling of thin-walled workpieces. The helical fluted end mi ll is modeled with the pre-twisted Timoshenko beam element that can more ac curately simulate the specific geometry and structural behavior of the cutt er. The workpiece is modeled with a 3D isoparametric 12-node element that c an take into account the geometry and thickness variations of the workpiece during peripheral milling. This study neglects the dynamic effect during m illing and assumes that the tool and the workpiece deform to their static e quilibrium positions at any milling instant. For a flexible cutting system, the effect of cutting system deflections on the cutting force distribution must be included. Hence the cutting force distribution and the cutting sys tem deflections are solved iteratively by the modified Newton-Raphson metho d in this study. After the converged cutting system deflections are obtaine d at each cutting step, the surface dimensional error of the workpiece at t he corresponding grid point can be computed easily. From the present study it is found that there will exist serious surface dimensional errors in the peripheral milling of very flexible components even the metal removal rate is very small. The present simulation model is verified experimentally and is helpful in determining the cutting parameters without performing real c utting experiments. (C) 1999 Elsevier Science S.A. All rights reserved.