Variable focus tool-path planning algorithm for virtual-axis elastic polishing machine tool

Based on a virtual-axis elastic polishing machine tool, in this article, we present a set of variable focus (VF) approaches to mimic iso-circuit and iso-spiral human polish behavior. We introduced an overlap subdivision method to cut out all of the zigzag turnings and sharp corners of the tool-path except for that on the edges of the work-piece. So the C¹ continuous offset quasi-circles were generated and finally the smooth and unbroken iso-spiral tool-path was produced. An adjustable overlap ratio was defined and the evaluation of machining efficiency was handed out. It is an easy task to implant the algorithm into a surface interpolation based on NURBS standard for direct interpolation. We simulated the approaches with Matlab to verify them.