A new approach for finishing free-form surfaces based on local shapes

摘要

This article presents a new approach for finishing free-form surfaces on three-axis computer numerical control (CNC) milling machines using ball-end mill tools. The proposed approach includes four stages and it is based on the localisation of local shapes composing the surfaces. In the first stage, the surfaces are triangulated semi-adaptively. In the second stage, the triangles having the same local shape are grouped into distinct sub-regions (concave developable, concave, convex developable, convex, planar and saddle) and the associated theoretical tool radius is calculated. In the third stage, the final optimum tools are determined and an assignment mode of tools is proposed. In the final stage, the optimum machining strategy for each sub-region is selected and finally the tool path is generated. The proposed approach has been tested in simulation over several free-form surfaces and the results show that it is efficient, especially when the surfaces are composed of many different local shapes.