Tool Path Planning for 3-Axis NC-Milling Lathe and 3-Axis NC-Vertical Milling for Sculptured Surfaces Machining Using Triangular Mesh Offset

Abstract

Since the evolution of human civilization, humans are making sculpture on wood, clay and rocks. Even now rural artists like wood maker are making designed sculpture surfaces by hand. Today machining relies heavily on CNC machine for conventional job, but no machines are made for sculptured surfaces. Though there are some CNC machines specially for machining sculptured work their cost are way beyond the limit of artists. The present work involves methodology of tool path generation by surface offset method for cheap and efficient NC-machine which can be used by artists easily without learning the detailed technical. CNC machines have controllers which use ISO G-code programming language or some machine specific proprietary languages which do not contain any part geometry information. The used NC machine reduces the requirement of costly controller by using computer as a controller. The present work involves Tool path planning for 3-Axis NC-Milling Lathe and 3-Axis NC-Vertical Milling for sculptured surfaces machining using triangular mesh offset. The methodology used in this work is for such PC based NC machine which takes the part geometry information as CL point in Cartesian coordinate. A unique surface offset algorithm is used to generate tool path surface by offsetting the surfaces by tool radius. The center of the ball nosed milling cutter travel along the offset surface where the offset surface acts as a CL point and the center of the ball nosed milling cutter act as CC point. The offsetting is done for both rouging pass and finish pass with different tool radius respectively. Once the surface is offset then tool path planning for milling lathe and vertical milling machine is performed by ray intersection methodology separately for rouging and finishing pass with variable pitch assuming the milling cutter as a ray which intersect the offset STL surface to generate the cutter location points the CL points are arrange systematically to generate tool path for milling lathe and vertical milling. The computer algorithm has been developed and verified by presenting in Cartesian coordinate format in MATHCAD® graphics representation. The machining operation for various types of models like twisted square, simple cylinder, cube, ring and some design like snake wrapped on cylinder has been performed successfully and presented in the report.