Precision machining system and methods

• US 20070221019A1
• Filed: 03/13/2006
• Published: 09/27/2007
• Est. Priority Date: 03/13/2006
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Liu, Xinbing, Ethington, Jon
• Granted Patent: US 7,788,998 B2
• Time in Patent Office: Days
• US Class Current: 82/117
• CPC Class Codes: B23B 1/00 Methods for turning or working essentially requiring the use of turning-machines; Use of auxiliary equipment in connection with such methods
• CPC Class Codes: B23B 2226/31 Diamond
• CPC Class Codes: Y10T 82/25 Lathe
• CPC Class Codes: Y10T 82/2512 having facing tool fed transverse to work
• CPC Class Codes: Y10T 82/2585 Tool rest
• CPC Class Codes: Y10T 82/2591 Tool post

Abstract

A precision machining system with a variable projected machining width of the cutting surface of the machining tool, including: a workpiece holder to hold a workpiece; a machining tool holder to hold the machining tool such that the Z axis is substantially parallel to the tool'"'"'s centerline; a Z translation stage and an X translation stage each coupled to one of the workpiece holder or the machining tool holder; a workpiece spindle coupled to the workpiece holder to rotate the workpiece about the workpiece axis that is parallel to the Z axis; a machining path controller electrically coupled to the X translation stage and the workpiece spindle; and a tool spindle coupled to the machining tool holder. The tool spindle rotates the machining tool about the centerline of the machining tool, which varies the width of the cutting surface of the machining tool projected perpendicular to the machining path.

Claims

1. A precision machining system with a variable projected machining width of a cutting surface of a machining tool, the precision machining system comprising:

a workpiece holder to hold a workpiece for machining;

a machining tool holder to hold the machining tool such that a Z axis is substantially parallel to a centerline of the machining tool;

a Z translation stage coupled to at least one of the workpiece holder or the machining tool holder to control a relative Z position of a tip of the machining tool and a surface of the held workpiece;

an X translation stage coupled to at least one of the workpiece holder or the machining tool holder;

a workpiece spindle coupled to the workpiece holder to rotate the workpiece about a workpiece axis parallel to the Z axis;

a machining path controller electrically coupled to the X translation stage and the workpiece spindle, the machining path controller controlling the X translation stage and the workpiece spindle such that the tip of the machining tool traverses a machining path on the surface of the held workpiece; and

a tool spindle coupled to the machining tool holder to rotate the machining tool about the centerline of the machining tool, thereby varying a width of the cutting surface of the machining tool projected perpendicular to the machining path.

2. The precision machining system according to claim 1, wherein the machining tool holder includes vibration means to vibrate the machining tool substantially parallel to the Z axis.

3. The precision machining system according to claim 2, wherein the vibration means is at least one of a piezoelectric transducer, a linear motor, or a voice coil actuator.

4. The precision machining system according to claim 2, wherein the vibration means has a maximum travel distance of less than about 200 μ

m.

5. The precision machining system according to claim 2, wherein the vibration means has a bandwidth of less than about 2 KHz.

6. The precision machining system according to claim 1, wherein the machining tool is one of a diamond machining tool, a sapphire machining tool, a silicon-carbide machining tool, a tungsten machining tool, or a tungsten-carbide machining tool.

7. The precision machining system according to claim 1, wherein:

the cutting surface of the machining tool has a first side cutting edge and a second side cutting edge;

a cross section of the cutting surface of the machining tool normal to the centerline of the machining tool is concave between the first cutting edge and the second cutting edge; and

the tool spindle is controlled to rotate the machining tool about the centerline of the machining tool through a range of angles such that;

a first plane tangent to the cutting surface at the first cutting edge meets the machining path to form one of an acute angle or a right angle on the surface of the held workpiece; and

a second plane tangent to the cutting surface at the second cutting edge meets the machining path to form one of an acute angle or a right angle on the surface of the held workpiece.

8. The precision machining system according to claim 1, wherein the machining path controller is further electrically coupled to the Z translation stage to control the Z translation stage such that the tip of the machining tool maintains a predetermined machining depth in the surface of the held workpiece as the tip of the machining tool traverses the machining path on the surface.

9. The precision machining system according to claim 1, further comprising:

a Y translation stage coupled to at least one of the workpiece holder or the machining tool holder;

wherein the machining path controller is further electrically coupled to the Y translation stage and the machining path controller controls the X translation stage, Y translation stage, and the workpiece spindle such that the tip of the machining tool traverses the machining path on the surface of the held workpiece.

10. The precision machining system according to claim 1, wherein the machining path controller includes at least one of special purpose control circuitry, an application specific integrated circuit, a general purpose computer, or a digital signal processor.

11. The precision machining system according to claim 1, wherein the machining path controller controls the X translation stage and the workpiece spindle such that a speed with which the tip of the machining tool traverses the machining path on the surface of the held workpiece is maintained at a machining speed.

12. The precision machining system according to claim 11, wherein the machining path controller controls the X translation stage and the workpiece spindle such that the machining speed is reduced:

proximate to a starting point of the machining path on the surface of the held workpiece to reduce a lead-in transition length; and

proximate to an ending point of the machining path to reduce a lead-out transition length.

13. The precision machining system according to claim 1, wherein machining path controller is further electrically coupled to the tool spindle to control the width of the cutting surface of the machining tool projected perpendicular to the machining path as the tip of the machining tool traverses the machining path on the surface of the held workpiece.

14. The precision machining system according to claim 1, wherein the tool spindle further includes a locking mechanism to lock the machining tool substantially at a predetermined angle to the machining path such that the width of the cutting surface of the machining tool projected perpendicular to the machining path is a predetermined width.

15. A method of machining a surface of a workpiece using a precision machining system adapted to project a cutting surface of a machining tool with a variable machining width, the method comprising the steps of:

a) mounting the workpiece in the precision machining system;

b) aligning a tip of the machining tool over a starting location of the surface of the workpiece such that the cutting surface of the machining tool is substantially perpendicular to the surface of the workpiece;

c) rotating the machining tool about an axis substantially normal to the surface of the workpiece until a width of the cutting surface of the machining tool projected perpendicular to a machining path on the surface of the workpiece is a predetermined machining width;

d) moving at least one of the workpiece or the machining tool in a direction substantially normal to the surface of the workpiece until the tip of the machining tool is at a predetermined machining depth in the surface of the workpiece; and

e) moving at least one of the workpiece or the machining tool substantially parallel to the surface of the workpiece such that the tip of the machining tool traverses the machining path on the surface of the workpiece.

16. The method according to claim 15, wherein step (e) includes the steps of:

e1) moving one of the workpiece or the machining tool in a first direction that is substantially parallel to the surface of the workpiece;

e2) moving the one of the workpiece or the machining tool in a second direction that is substantially parallel to the surface of the workpiece and is not substantially parallel to the first direction; and

e3) coordinating the movements in the first direction and the second direction such that the tip of the machining tool traverses the machining path on the surface of the workpiece.

17. The method according to claim 15, wherein step (e) includes the steps of:

e1) moving one of the workpiece or the machining tool in a first direction in a plane substantially parallel to the surface of the workpiece;

e2) moving the other one of the workpiece or the machining tool in a second direction in the plane substantially parallel to the surface of the workpiece that is not parallel to the first direction; and

e3) coordinating the movements in the first direction and the second direction such that the tip of the machining tool traverses the machining path on the surface of the workpiece.

18. The method according to claim 15, wherein step (e) includes the steps of:

e1) rotating the workpiece about an axis that is substantially normal to the surface of the workpiece;

e2) moving one of the workpiece or the machining tool in a radial line that is substantially parallel to the surface of the workpiece and intersects the axis; and

e3) coordinating the rotation about the axis and movement in the radial line such that the tip of the machining tool traverses the machining path on the surface of the workpiece.

19. The method according to claim 18, wherein step (e3) includes varying a rotational speed of the workpiece based on a position of the tip of the machining tool on the radial line such that a machining speed with which the tip of the machining tool traverses the machining path on the surface of the workpiece is substantially constant.

20. The method according to claim 15, wherein step (e) includes the steps of:

e1) moving at least one of the workpiece or the machining tool substantially parallel to the surface of the workpiece such that the tip of the machining tool traverses the machining path on the surface of the workpiece; and

e2) moving at least one of the workpiece or the machining tool in the direction substantially normal to the surface of the workpiece such that the tip of the machining tool is maintained substantially at the predetermined machining depth in the surface of the workpiece as the tip of the machining tool traverses the machining path on the surface of the workpiece.

21. The method according to claim 20, wherein the predetermined machining depth is different for different portions of the machining path.

22. The method according to claim 15, wherein step (e) includes the steps of:

e1) moving at least one of the workpiece or the machining tool substantially parallel to the surface of the workpiece such that the tip of the machining tool traverses the machining path on the surface of the workpiece; and

e2) rotating the machining tool about the axis substantially normal to the surface of the workpiece such that the width of the cutting surface of the machining tool projected perpendicular to the machining path on the surface of the workpiece is maintained substantially at the predetermined machining width as the tip of the machining tool traverses the machining path.

23. The method according to claim 22, wherein the predetermined machining width is different for different portions of the machining path.

24. A precision machining system adapted to project a cutting surface of a machining tool with a variable machining width, comprising:

alignment means for aligning a tip of the machining tool over a surface of a workpiece such that the cutting surface of the machining tool is substantially perpendicular to the surface of the workpiece;

tool rotation means for rotating the machining tool about an axis substantially normal to the surface of the workpiece to vary a width of the cutting surface of the machining tool projected perpendicular to a machining path on the surface of the workpiece;

normal movement means for moving at least one of the workpiece or the machining tool in a direction substantially normal to the surface of the workpiece; and

parallel movement means for moving at least one of the workpiece or the machining tool substantially parallel to the surface of the workpiece.