Analysis of milling surface roughness prediction for thin-walled parts with curved surface

Abstract

In manufacturing industry, parts contain curved surface are widely used to meet specific needs like better performance, beautiful appearance, and light weight. Surface roughness is an important part of machining surface topography. The milling surface roughness prediction of thin-walled parts with curved surface and physical factors are studied in this paper. Based on the theory of milling process, modeling theory of differential geometry and computer graphic, a milling surface roughness prediction model is deduced. This paper futher discretized the ball end milling edge, and built the tool feed model, cutting edge conversion model, and tool axis control model, based on differential geometry theory. Z-map model is used to mesh the workpiece. Combining tool’s motion model during milling process with workpiece meshing model, the basic milling surface roughness prediction model is deduced. Considering the physical factors’ influence, based on the micro-unit cutting force modeling theory and two-segment cantilever beam tool deformation theory, ball end milling cutter’s forced deformation model is deduced by analytical calculation. Considering the tool wear in milling process and analyzing tool wear in the initial wear stage, the tool wear correction model is built. The comprehensive milling surface roughness prediction model is established by introducing the tool wear model and tool forced deformation model into basic surface roughness prediction model. An experimental verification is set up by the central composite design method, the result show that error of surface roughness prediction model is less than 13%. This experiment verifies that the milling surface roughness prediction model based on milling theory established in this paper is of high precision, and surface roughness can be quantitatively predicted.