A method for generating trochoidal tool paths for 21/2 D pocket milling process planning with multiple tools

When used in pocket roughing, both the direction-parallel and the contour-parallel tool path strategies usually create critical cutting regions in corners and narrow slots, which can be problematic to machine. The utilization of a trochoidal tool path has been proposed recently in order to avoid these problems. In this work, a method for generating trochoidal tool paths for 21/2D pocket milling using a medial axis transform is proposed. In order to achieve this goal, first the pocket and islands are represented as polygons, and the medial axis transform is calculated as a series of points. The points are then sorted and grouped by an algorithm that generates the trochoidal path whenever the desired radial depth of cut is attained. In the proposed method, machining time is reduced through a pixel-based simulation, adjusting the tool path to the remaining material. The tool path generation method allows the control of the maximum radial depth of cut, avoiding the momentary increments in radial depth of cut, since those increments are problematic when machining hard materials or when high speed machining. Also, a cutting tool selection and area segmentation method using different tool sizes are used.