Engagement milling

1. A method implemented in a computer for generating a tool path for milling a region of a workpiece by a numerical control machine using a milling cutter, the tool path comprising one or more passes, each pass forming an in-process material boundary comprising a plurality of tangential continuous arcs, each pass successively advancing into the region by a predetermined pitch, the region having first, second and third sides, the first side being a current in-process material boundary and the second and the third sides being part or material boundaries, the first side meeting at its respective ends the second and the third sides, the method for determining parameters of each one of the one or more passes comprising the steps of:

receiving parameters describing the region;

determining the parameters of a first one of the plurality of tangential continuous arcs to be tangent to the second side and having a radius of curvature greater than one-half of a distance between the second and third sides at the points where the first side meets the second and the third sides; and

determining the parameters of a second one of the plurality of tangential continuous arcs, said second one of a plurality of tangential continuous arcs being joined at one end to one end of the first one of the plurality of tangential continuous arcs and to be tangent to the third side, and having a radius of curvature less than one-half the distance between the second and the third sides at the points where the first side meets the second and the third sides, and

outputting a series of instructions useful for controlling the numerical control milling machine to mill the region in accordance with the generated tool path.

2. The method of claim 1 , wherein the region is a slot.

3. The method of claim 1 wherein each in-process material boundary consists of two arcs.

4. The method of claim 3 , wherein each of the arcs is circular.

5. The method of claim 1 , wherein the pitch is determined such that a maximum value of engagement of the milling cutter when milling each one of the in-process material boundaries is substantially equal to a predetermined maximum value of engagement.

6. The method of claim 5 , further including the step of adjusting the radius of each first tangential arc and each second tangential arc such that the pitch is maximized.

7. The method of claim 5 , wherein the wherein the pitch is based on a distance between the second side and the third side and the radius of the milling cutter.

8. The method of claim 1 , wherein a radius of the milling cutter is selected such that a width of the first side is from 2.2 to 5 times the radius of the milling cutter.

9. An article of manufacture comprising a computer readable medium having stored thereon computer executable instructions for generating a tool path for milling a region of a workpiece by a numerical control machine using a milling cutter, the tool path comprising one or more passes, each pass forming an in-process material boundary comprising a plurality of tangential continuous arcs, each pass successively advancing into the region by a predetermined pitch, the region having first, second and third sides, the first side being a current in-process material boundary and the second and the third sides being part or material boundaries, the first side meeting at its respective ends the second and the third sides, the method for determining parameters of each one of the one or more passes comprising the steps of:

receiving parameters describing the region;

determining the parameters of a first one of the plurality of tangential continuous arcs to be tangent to the second side and having a radius of curvature greater than one-half of a distance between the second and third sides at the points the first side meets the second and the third sides; and

determining the parameters of a second one of the plurality of tangential continuous arcs, said second one of a plurality of tangential continuous arcs being joined at one end to one end of the first one of the plurality of tangential continuous arcs and to be tangent to the third side, and having a radius of curvature less than one-half the distance between the second and third sides at the points where the first side meets the second and the third sides, and

outputting a series of instructions useful for controlling the numerical control machine to mill the region in accordance with the generated tool path.

10. The article of manufacture of claim 9 , wherein the region is a slot.

11. The article of manufacture of claim 9 , wherein each in-process material boundary consists of two arcs.

12. The article of manufacture of claim 11 , wherein each of the arcs is circular.

13. The article of manufacture of claim 9 , wherein the pitch is determined such that a maximum value of engagement of the milling cutter when milling each one of the in-process material boundaries is substantially equal to a predetermined maximum value of engagement.

14. The article of manufacture of claim 13 , further including the step of adjusting the radius of each first tangential arc and each second tangential arc such that the pitch is maximized.

15. The article of manufacture of claim 13 , wherein the wherein the pitch is based on a distance between the second side and the third side and the radius of the milling cutter.

16. The article of manufacture of claim 9 , wherein a radius of the milling cutter is selected such that a width of the first side is from 2.2 to 5 times the radius of the milling cutter.