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Abstract
Today, sculptured parts are widely used in aeronautical, automotive, and many other industries. To make high-quality sculptured surfaces through efficient toolpaths in three-axis CNC machining is a major technical challenge. In this work, a new toolpath generation method for three-axis CNC milling, the Steepest-Directed and Iso-Cusped (SDIC) toolpath generation scheme, is introduced. The method integrates the steepest-directed and iso-cusped toolpaths in three-axis CNC programming. The sfeepesf-d/recfedtoolpaths ensure the best geometry matching between cutter and surface for high cutting efficiency, and form a frame to control the trend in direction of the iso-cusped toolpaths. The iso-cusped toolpaths eliminate overmachining on the surface. Their combination ensures high sculptured part productivity, less redundant milling, and good surface quality. Machining examples of a half-cylinder part and a sculptured part are used to illustrate and to compare a range of SDIC toolpath patterns. The proposed SDIC toolpath scheme produces shorter toolpaths with higher machining efficiency. With the help of global optimization algorithms, this method of optimal toolpath generation can be applied to three-axis CNC machining of sculptured surfaces.
Keywords: Toolpath Generation, CNC Programming, Sculptured Part Machining, Three-Axis Machining, Finish Machining
Introduction
Mechanical parts with sculptured surfaces are widely used in aeronautical, automotive, and domestic electronic industries due to their unique functions and appearance. Machining these parts, or their dies and molds, is mostly carried out with three-axis CNC machines. Over the years, significant progress has been made in sculptured part modeling and toolpath generation of three-axis CNC machining.
However, due to the diversity and complexity of sculptured surfaces, a general method of generating three-axis CNC machining toolpaths that guarantees high-quality finished surfaces and also ensures high machining efficiency remains a major technical challenge. This is particularly true for the case of finish machining. The objective of finish machining is to remove the unevenly distributed excess material produced in rough machining to form a finished surface satisfying the specified accuracy and tolerance. Tolerance determines how much finish machining is needed, which in turn determines the amount of finishing and polishing operations. The ideal toolpath is one that produces satisfactory surface quality with a minimum of machining time. At present, research on finish machining of sculptured surfaces primarily focuses on the surface quality through various toolpath generation methods that...