AN ALGORITHM FOR FREE FORM SURFACE PARTITIONING BASED ON SURFACE CURVATURE VALUES UNDER CONTROL PROGRAM DEVELOPMENT FOR CNC MACHINE-TOOLS

Abstract

The PURPOSE of the study is to develop an algorithm of free-form surface partitioning into local domains (individual regions), construction of boundaries between these regions and preparation of the initial data for the formation of an optimal technological process of machining and preparation of control programs for shaping such surfaces. METHODS. Partitioning is based on the mean and Gaussian curvature in the points of a free-form surface. The coordinates of the 3D model grid nodes or the data for NURBS surface construction are proposed to be used as initial data or the analysis of the surface region geometry. The Matlab software package has been used for mesh partitioning. A program has been developed to implement the algorithm and determine the coordinates of domain regions which can be imported into any CAD/CAM programs. RESULTS AND THEIR DISCUSSION. The algorithm allows partitioning of free-form surfaces into flat, convex, concave and saddle-type regions. Modern milling machines can be used to obtain these kinds of surfaces on the parts of various products. These machines must be also equipped with the tools of various sizes and product lines. Their number and machining strategies which determine the toolpaths on the surface regions in relation to the workpiece have a significant influence on milling performance. CONCLUSIONS. The obtained data serve as a basis for tool selection and solving of the optimization problem of toolpath planning under multi-axis end milling depending on the shape of the surface regions.