HIGH-PRECISION MICRO/NANO-SCALE MACHINING SYSTEM

• US 20110132169A1
• Filed: 09/08/2010
• Published: 06/09/2011
• Est. Priority Date: 09/08/2009
• Status: Active Grant

• Current Assignee: Board of Trustees of The University of Illinois
• Original Assignee: Board of Trustees of The University of Illinois
• Inventors: Bourne, Keith Allen, DeVor, Richard E., Kapoor, Shiv G.
• Granted Patent: US 8,806,995 B2
• Time in Patent Office: Days
• US Class Current: 83/875
• CPC Class Codes: B26D 1/0006 Cutting members therefor
• CPC Class Codes: B26D 2001/002 Materials or surface treatments therefor, e.g. composite materials
• CPC Class Codes: B26D 2001/0053 having a special cutting edge section or blade section
• CPC Class Codes: B26D 2001/006 the cutting blade having a special shape, e.g. a special outline, serrations
• CPC Class Codes: B26D 3/06 Grooving involving removal of material from the surface of the work
• CPC Class Codes: B26D 3/08 Making a superficial cut in the surface of the work without removal of material, e.g. scoring, incising
• CPC Class Codes: Y10T 82/10 Process of turning
• CPC Class Codes: Y10T 82/2502 with program control
• CPC Class Codes: Y10T 82/2535 Electrical type
• CPC Class Codes: Y10T 82/2585 Tool rest
• CPC Class Codes: Y10T 83/0304 Grooving
• CPC Class Codes: Y10T 83/929 Tool or tool with support

Abstract

A high precision micro/nanoscale machining system. A multi-axis movement machine provides relative movement along multiple axes between a workpiece and a tool holder. A cutting tool is disposed on a flexible cantilever held by the tool holder, the tool holder being movable to provide at least two of the axes to set the angle and distance of the cutting tool relative to the workpiece. A feedback control system uses measurement of deflection of the cantilever during cutting to maintain a desired cantilever deflection and hence a desired load on the cutting tool.

Claims

1. A high precision micro/nanoscale machining system, comprising:

a multi-axis movement machine providing relative movement along multiple axes between a workpiece and a tool holder;

a cutting tool on a flexible cantilever held by the tool holder;

the tool holder being movable to provide at least two of the axes to set the angle and distance of the cutting tool relative to the workpiece; and

a feedback control system that uses measurement of deflection of the cantilever during cutting to maintain a desired cantilever deflection and hence a desired load on the cutting tool.

2. The system of claim 1, wherein said feedback control system comprises a control system including a proportional-integral-derivative (PID) control algorithm with feedforward for each of the axes to control the tool holder position to maintain the desired cantilever deflection.

3. The system of claim 1, wherein the desired cantilever deflection is either constant or varied to achieve a desired cutting profile.

4. The system of claim 1, wherein said control system sets the cantilever angle in a manner that achieves a desired cutting geometry orientation during cutting using a 2D model that accounts for loads applied to a tip of the cutting tool normal to the workpiece, the probe mounting angle, and the location of the cutting edge (contact point) relative to the end of the cantilever.

5. The system of claim 1, wherein said cutting tool and said flexible cantilever comprise a probe of an atomic force microscope (AFM).

6. The system of claim 5, wherein the probe is modified to have a predetermined cutting geometry that provides a back rake face and an end clearance face.

7. The system of claim 1, wherein a cutting tool is shaped to have a predetermined cutting geometry that provides a well defined rake face and that has a shape that enables the machining of a groove with a desired shape, an end clearance face, and side clearance faces;

the cutting geometry being sufficient to withstand the forces applied to it during cutting and to wear in a gradual manner.

8. The system of claim 1, further comprising:

a displacement sensor coupled to said feedback control system for measuring deflection of the cantilever.

9. The system of claim 8, wherein said displacement sensor comprises at least one of a laser displacement sensor and a strain gage integrated into the cantilever.

10. A high precision micro/nanoscale machining system comprising:

a single or multiple point cutting tool mounted on a flexible cantilever, the cutting tool having a geometry suitable for groove and pocket cutting;

a precision displacement sensor to measure deflection of the cantilever during cutting;

a multi-axis motion platform providing relative x, y, and z axis movements and rotational movements between a workpiece and the cutting tool; and

a feedback control system that uses measurement of tool cantilever deflection during cutting to maintain a constant cantilever deflection and hence a constant load on the cutting tool.

11. The system of claim 10, wherein the cutting tool is mounted on a tool holder and the tool holder is rotated using a rotary stage in order to achieve a desired cutter orientation when the flexible cantilever portion of the tool experiences deflection.

12. The system of claim 10, wherein the feedback control system uses a 2D beam model to calculate the amount of rotation required to achieve a desired cutting orientation by accounting for loads applied to the tool normal to the workpiece and the tool geometry.

13. A method of machining a workpiece comprising:

placing the workpiece on a multi-axis movement machine that provides relative movement along multiple axes between a workpiece and a tool holder;

positioning a cutting tool on a flexible cantilever held by the tool holder towards the workpiece, the tool holder being movable to provide at least two of the axes to set the angle and distance of the cutting tool relative to the workpiece;

contacting the cutting tool to the workpiece, wherein a load is provided on the cutting tool and the flexible cantilever is deflected;

moving at least one of said cutting tool and said workpiece to machine the workpiece;

during said moving, measuring deflection of the cantilever; and

repositioning the tool holder based on said measured deflection to maintain a desired cantilever deflection and hence a desired load on the cutting tool.

14. The method of claim 13, wherein said repositioning comprises a feedback control system using said measured deflection and controlling said tool holder.

15. The method of claim 13, wherein said feedback control system sets a cantilever angle in a manner that achieves a desired cutting geometry orientation during cutting using a 2D model that accounts for loads applied to a tip of the cutting tool normal to the workpiece, the probe mounting angle, and the location of the cutting edge (contact point) relative to the end of the cantilever.

16. The method of claim 15, further comprising:

calibrating the measured deflection to a load on the cutting tool.

17. The method of claim 13, wherein said repositioning comprising adjusting a distance of the tool holder relative to the workpiece.

18. A tool for microscale or nanoscale machining comprising:

a flexible cantilever;

a cutting geometry disposed at an end of said flexible cantilever, said cutting geometry comprising a well defined rake face, clearance faces, and at least one cutting edge.

19. The cutting tool of claim 18, wherein said at least one cutting edge comprises a plurality of cutting edges.

20. A high precision micro/nanoscale machining system, comprising:

means for microscale or nanoscale cutting;

flexible cantilever means for supporting said means for cutting;

means for holding said flexible cantilever means;

means for providing relative movement along multiple axes between a workpiece and said means for holding;

said means for providing relative movement comprising means for setting an angle and distance of said means for cutting relative to the workpiece;

means for measuring deflection of said flexible cantilever means; and

feedback control mean for receiving said measured deflection and maintaining a desired deflection of said flexible cantilever means and hence a desired load on said means for cutting.