CNC Tool Path Generation for Constant Engagement Milling

The patent changes the fundamental parameter of tool path generation from boundary-following to engagement-based. Instead of generating tool paths that follow part boundaries, the system generates tool paths that maintain constant tool engagement by controlling the radial depth of cut and using engagement-based stepover calculations. This parameter change eliminates engagement spikes while maintaining manufacturability through automated CAM programming.

The patent applies preliminary action by calculating and establishing the maximum engagement angle and corresponding feed rate limits before generating the tool path. The system determines the maximum radial depth of cut and uses these pre-calculated parameters to generate the entire tool path, ensuring that engagement never exceeds the maximum. This allows the mill to operate at or near maximum feed rates throughout the entire path without encountering engagement spikes that would require speed reductions.

The patent implements feedback by continuously calculating the actual tool engagement and undeformed chip thickness along the tool path based on the generated path geometry and cutting parameters. The system uses these calculated values to verify that engagement remains within maximum limits and to adjust feed rates accordingly. This closed-loop approach provides precise tool load control while maintaining automated operation.

The patent applies inversion by reversing the traditional approach: instead of generating a tool path based on part geometry and then modifying it to correct engagement issues, the system generates the tool path directly from engagement constraints. The tool path is created by offsetting the part boundary by a calculated stepover distance that ensures constant engagement, eliminating the need for subsequent corrections and avoiding increases in total path length.