Generalized Tool Path Planning Approach for Finish Machining for 3-Axis Vertical Milling

Abstract

The generalized tool path planning approach for finish machining has been presented in the present thesis work. The aim of present work is development of generalized tool path planning for finish machining / pencil cutting for 3-axis vertical milling. The CAD modeller provides the information about the part geometry, which has been taken as STL file (Stereo Lithography). The STL data has been used as input to the tool path generation algorithm, which calculates the cutter location (CL) points for a pre-decided density of CL positions in X-Y plane. With the help of CL data as input for pencil cut tracing algorithm, the CL data pints for continuous contoured pencil cutting operation has been extracted. Tool path generation strategies for pencil cutting have been discussed in detail. Also the literature about the side feed, forward feed and triangular mesh have been discussed. Various checks have been applied in the algorithm to find the best suitable point at particular tool position for finding the best CL data net and Pencil cutting data. The main features of the proposed approach are the extraction of pencil-cut points from the CLsurface,which has been scanned in X and Y directions by continuously comparing the Z level values of respective CL points. The relationship for estimation of the scallop height for ball end mill has been used to find the best CL data density for finding the appropriate pencil cutting positions. It is well known fact that the scallop height can be reduced with the help of reducing the side step value between two adjacent tool paths. The process of generating pencil-cut path is clear to understand, robust, and efficient, and the quality of the resulting path is high. The main techniques used for the tool path planning, positioning and pencil cutting tool path have been discussed and the results have been presented in a logical way. The verification and testing of the accuracy of the pencil cutting algorithm has been done using a graphical simulator for 3-axis NC machining.