Research On Tool-path In The Process Of Sculptured Surface NC-machining

Along with the development of science and technology, free-form surfaces is already the most complicated and often applied in the engineering, in the field of aviation, shipbuilding, automobile, power and energy industry many shapes of workpieces are space curved surface, such as airfoil of airplane, body of car, surface of die and mould part. More and more these complicated parts, the accuracy requests are increasingly high. To find solutions to complex and precision components machining, NC-technology has been widely studied and applied. Tool-path generation method has been the most important and the most extensive and in-depth content for the free-form surface parts NC-machining. In the multi-axis NC-machining, tool-path influences on the precision and efficiency of machining.The paper introduces a free-form surface subdivision algorithm based on curvature and fuzzy C-means method. Free-form surface is divided into certain curved surface pieces through the algorithm. Those curved surface pieces are turned over classification and the race. Namely clustering curved surface piece race. Finally according to characteristics of different patch, curved surface pieces are machined by suitable tool-path generation method.The paper presents the offset method to find critical regions (gouging regions) boundary and to generate tool-path machining the curved surface. The major idea is following: local gouging occurs when a concave region on a free-form surface has its minimum radius smaller than the cutter radius selected. According to the regulation, the complex surfaces are dispersed, and the gridding point-pairs (boundary points of critical region) that have the same offset point for offset distance given are found by the offset method. The gridding points are linked by line segment for the shortest principle. So the boundary of critical regions can be constructed, namely the boundary is composed of line segments linked each other. Finally suitable size cutters are selected to machine critical region. It makes NC-machining to avoid gouging as well as improved efficiency.The paper puts forward that curved surface pieces for different characteristics are machined by the isoparametric and the isoscallop tool-path generation method. Isoparametric method makes tool-path generation calculation simply and quickly; but the disadvantage is that cutting routes of tool-path are not uniformity and the methodhas lower efficiency for uneven distributing parameters. Isoscallop method has higher efficiency and better precision than other methods in the complex surface machining. So smooth curved surface pieces are machined by tool-path isoparametric method generated; and accidented curved surface pieces are machined by tool-path isoscallop method generated. It fully utilizes advantage of these tool-path methods, improves the processing efficiency of the surface.