Control for high speed cutting tool

• US 6,447,223 B1
• Filed: 06/07/2000
• Issued: 09/10/2002
• Est. Priority Date: 06/07/2000
• Status: Expired due to Term

• Current Assignee: PTC Inc.
• Original Assignee: PTC Inc.
• Inventors: Badics, Tamas T., Farah, Charles M.
• Primary Examiner(s): Howell, Daniel W.
• Application Number:
  US09/589,937
• Time in Patent Office: 825 Days
• Field of Search: 409/79, 409/80, 409/132, 700/172, 700/182, 700/184, 700/186, 700/187, 700/190, 700/191, 318/568.1, 318/570, 318/579
• US Class Current: 409/132
• CPC Class Codes: G05B 19/41 characterised by interpolation, e.g. the computation of intermediate points between programmed end points to define the path to be followed and the rate of travel along that path G05B19/25, G05B19/31, G05B19/37, G05B19/39, G05B19/40 take precedence
• CPC Class Codes: G05B 2219/34106 Using spiral collapsed boundary, contour parallel machining
• CPC Class Codes: G05B 2219/49082 Maintain constant material removal rate
• CPC Class Codes: G05B 2219/49354 High speed cutting
• CPC Class Codes: Y10T 409/300896 with sensing of numerical information and regulation without mechanical connection between sensing means and regulated means [i.e., numerical control]
• CPC Class Codes: Y10T 409/303808 including infeeding

Abstract

A computer-implemented method and system is disclosed for controlling a cutting tool of a high speed cutting machine. The method and system provides an effective tool path for controlling a cutting machine under a constant rate of material removal in a high speed cutting machine in order to get away with the extreme cutting forces. The tool path also allows to better transfer the heat generated between the cutting tool and the workpiece through the chip. The method and system can be applied to any geometry of final shape of a workpiece.

Claims

1. A computer-implemented method for machining selected portions of a workpiece by a cutting tool of a high speed cutting machine, said method comprising the steps of:

providing a horizontal slice of the selected portions of the workpiece;

determining an initial boundary of the slice, the boundary being open to the air;

generating subsequent boundaries in the selected portions of the slice, said subsequent boundaries being determined by removing the selected portions of the slice by a cutting depth of the cutting tool buried in the workpiece from the previous boundary;

generating a tool path based on the boundaries of the selected portions within the slice, said tool path being positioned in the air from the boundaries depending on the radius of the cutting tool and a predetermined value of the cutting depth of the cutting tool; and

machining said selected portions by moving the cutting tool along said generated tool path maintaining the cutting tool in a climb cutting condition as the cutting tool machines the selected portions of the workpiece to provide a constant tool load on the cutting tool.

2. The computer-implemented method of claim 1, wherein said predetermined value of the cutting depth of the cutting tool is determined by analyzing the reference part, tool shape and a workpiece shape.

3. The computer-implemented method of claim 2, wherein said predetermined value of the cutting depth of the cutting tool is equal to or less than a radius of the cutting tool.

4. The computer-implemented method of claim 1, wherein said boundary determining includes:

where the selected portions of the slice have no initial boundary that is open to the air, generating an initial boundary in the selected portion of the workpiece.

5. The computer-implemented method of claim 1, wherein said boundary determining includes:

determining whether the cutting tool is able to access the boundary; and

where the cutting tool is not able to access the workpiece, generating an initial boundary by opening an area in the selected portions of the slice.

6. The computer-implemented method of claim 5, wherein said opening an area in the selected portion of the workpiece includes:

moving down the cutting tool in a spline helical manner until the depth of the slice is reached.

7. The computer-implemented method of claim 1, wherein said tool path generating comprises:

determining a tool path by moving an initial boundary into the air by a radius of the cutting tool minus the cutting depth of the cutting tool buried in the workpiece.

9. The computer-implemented method of claim 1 further comprising:

ordering the cutting tool path to minimize a traveling distance of the cutting tool; and

connecting the cutting tool path within said selected portions of the slice to complete the cutting tool path.

10. The computer-implemented method of claim 9, wherein said connecting step includes:

determining whether an initial boundary of the selected portions of the slice is a closed loop; and

where the boundary is a closed loop, connecting a tool path generated based on the closed loop boundary to a next tool path by S motion.

11. The computer-implemented method of claim 9, wherein said connecting step includes:

accessing a starting end of an open loop tool path by a helical spline motion; and

exiting an ending position of an open loop tool center line by a helical spline motion.

12. The computer-implemented method of claim 1, wherein said machining step includes:

providing directional changes of the cutting tool along substantially helical trajectories so as to minimize sudden directional changes.

13. The computer-implemented method of claim 1, wherein the step of generating the cutting tool path creates the cutting tool path to maximize the engagement of the cutting tool with the workpiece.

14. The computer-implemented method of claim 1, wherein the step of generating the cutting tool path creates the cutting tool path such that the cutting tool machines the workpiece, when possible, from outside of the workpiece.

15. The computer-implemented method of claim 1, wherein the step of generating the cutting tool path creates the cutting tool path such that the cutting tool enters a portion of the workpiece without a border with the outside environment along a substantially helical trajectory.

8. A controller for controlling a cutting tool of a high speed cutting machine, comprising:

a memory element for storing instructions for controlling the cutting tool and data regarding the workpiece required to control the cutting tool; and

a processor operated by the instructions stored in the memory element for controlling signals for a tool path of the cutting tool, said processor includes

means for horizontally slicing the selected portion of the workpiece using the data regarding the workpiece stored in the memory,

means for examining the data of a slice of the workpiece to determine an initial boundary of the selected portion of the slice,

means for generating subsequent boundary data of the selected portions of the slice, said subsequent boundary data being determined by subtracting the cutting depth of the cutting tool buried in the workpiece from the previous boundary data, and

means for generating signals for a tool path, the cutting tool path being positioned in the air remote from the boundaries depending on the radius of the cutting tool and a predetermined value of the cutting depth of the cutting tool,

wherein said cutting tool maintains a climb cutting condition as the cutting tool machines the selected portions of the workpiece to provide a constant tool load on the cutting tool.

16. The controller of claim 8, wherein the cutting tool rotates at a rate higher than 60,000 rpm while machining the workpiece.

17. The controller of claim 8, wherein said predetermined value of the cutting depth of the cutting tool is determined by analyzing the reference part, tool shape and a workpiece shape.

18. The controller of claim 17, wherein said predetermined value of the cutting depth of the cutting tool is equal to or less than a radius of the cutting tool.

19. The controller of claim 8 further comprising means for generating an initial boundary in the selected portion of the workpiece for the cutting tool to access.

20. The controller of claim 19 further comprising means for generating signal for moving down the cutting tool in a spline helical manner until the depth of the slice is reached, to open up an area for the cutting tool to access.

21. The controller of claim 8, wherein said tool path is determined by moving boundaries into the air by a radius of the cutting tool minus the cutting depth of the cutting tool buried in the workpiece.

22. The controller of claim 8, wherein said cutting tool enters a portion of the workpiece without a border with the outside environment from outside of the workpiece along a substantially helical trajectory.

23. The controller of claim 8, wherein said processor further comprises:

means for ordering the cutting tool path to minimize a traveling distance of the cutting tool; and

means for connecting the cutting tool path within said selected portions of the slice to complete the cutting tool path.

24. The controller of claim 23, wherein said tool path of a closed loop boundary is connected to a next tool path by S motion.

25. The controller of claim 23, wherein said directional changes of the cutting tool is provided along substantially helical trajectories so as to minimize sudden directional changes and characterized by maximizing engagement of the cutting tool with the workpiece.

26. The controller of claim 23, wherein said cutting tool accesses a starting end of an open loop tool path by a helical spline motion.

27. The controller of claim 23, wherein said cutting tool exits an ending position of an open loop tool path by a helical spline motion.

28. The controller of claim 8, wherein said cutting tool machines the workpiece, when possible, from outside of the workpiece.