Numerical prediction of static form errors in the end milling of thin-walled workpiece

Cutting deformation is the key factor influencing the precision and quality of the machined thin-walled workpiece, and to keep the maximum surface form errors under the permissible errors is the ultimate purpose of the form errors prediction. Cutting forces are analyzed and classified into six types according to combination of cutting depth, and cutting-force model for thin-walled workpiece machining is developed, then a finite-element model is presented to analyze the surface dimensional errors in peripheral milling of aerospace thin-walled workpieces. The efficient flexible iterative algorithm is proposed to calculate the deflections and the maximum surface form errors as contrasted with the rigid iterative algorithm used in the literatures. Meanwhile, some key techniques such as the finite-element modeling of the tool-workpiece system; the determinant algorithm to judge instantaneous immersion boundaries between a cutter element and the workpiece; iterative scheme for the calculations of tool-workpiece deflections considering the former convergence cutting position; and the method for calculating the position and magnitude of the maximum surface form errors are developed and presented in detail. The presented simulation model can control the surface errors in the permissible errors region without calculating the errors all over the workpiece, hence computing speed is greatly increased. The proposed approach is validated and proved to be efficient through comparing the obtained numerical results with the test results.