Machine tool control methods and designs for fabricating mesoscopic surface structures on substrates

• US 7,203,569 B2
• Filed: 08/31/2004
• Issued: 04/10/2007
• Est. Priority Date: 08/31/2004
• Status: Expired due to Fees

• Current Assignee: Sabic Innovative Plastics IP BV (Government of Saudi Arabia)
• Original Assignee: General Electric Company
• Inventors: Olczak, Eugene George, Smolenski, Joseph Lucian, Liang, Erwin Wenti, Tanpitukpongse, Teeporn Paul, Robrigado, Eric Redito
• Primary Examiner(s): Kosowski; Alexander
• Application Number:
  US10/932,239
• Publication Number:
  US 20060047358A1
• Time in Patent Office: 952 Days
• Field of Search: 700/159, 700/186, 700/191, 700/193, 144/136.1, 82/11.1, 82/12, 82117-118, 821/73
• US Class Current: 700/186
• CPC Class Codes: B23B 2260/108 Piezoelectric elements
• CPC Class Codes: B23B 29/125 Vibratory toolholders
• CPC Class Codes: B23K 26/0823 Devices involving rotation of the workpiece
• CPC Class Codes: B23K 26/355 Texturing
• CPC Class Codes: B23K 26/364 for making a groove or trench, e.g. for scribing a break initiation groove
• CPC Class Codes: G05B 19/182 characterised by the machine tool function, e.g. thread cutting, cam making, tool direction control G05B19/21 - G05B19/40 take precedence
• CPC Class Codes: G05B 19/19 characterised by positioning or contouring control systems, e.g. to control position from one programmed point to another or to control movement along a programmed continuous path
• CPC Class Codes: G05B 2219/41344 Piezo, electrostrictive linear drive
• CPC Class Codes: G05B 2219/42209 Two slides, fine and quick, coarse and slow, piggyback, multirate positioner
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]
• CPC Class Codes: Y10T 82/2502 with program control

Abstract

There is provided a machining tool for machining a workpiece on a workpiece support in response to control signals. The machining tool includes a cutting tool configured to cut a surface of the workpiece. The machining tool also includes a first displacement mechanism and a second displacement mechanism. The first displacement mechanism arranged to displace the cutting tool relative to the workpiece in a first set of coordinates in response to the control signals. The second displacement mechanism supported by the first translation mechanism and arranged to displace the cutting tool relative to the workpiece in a second set of coordinates, the second displacement mechanism capable of a higher frequency response than the first displacement mechanism. The machining tool also includes a controller configured to receive the control signals and synchronize the displacement of the cutting tool due to the first displacement mechanism with the displacement of the cutting tool due to the second displacement mechanism.

Claims

1. A machining tool for machining a workpiece on a workpiece support in response to control signals, comprising:

a cutting tool configured to cut a surface of the workpiece;

a first displacement mechanism arranged to displace the cutting tool relative to the workpiece in a first set of coordinates in response to the control signals;

a second displacement mechanism supported by the first displacement mechanism and arranged to displace the cutting tool relative to the workpiece in a second set of coordinates, the second displacement mechanism capable of a higher frequency response than the first displacement mechanism; and

a controller configured to receive the control signals and synchronize the displacement of the cutting tool due to the first displacement mechanism with the displacement of the cutting tool due to the second displacement mechanism;

wherein the controller comprises;

a displacement determination unit that determines a target displacement of the cutting tool in the second set of coordinates and provides target displacement digital signals based on the determined target displacement;

a digital to analog unit comprising a plurality of digital to analog converters configured to receive respective of the target displacement digital signals from the displacement determination unit and convert the target displacement digital signals to target displacement analog signals; and

at least one switch to alternate which digital to analog converters release respective of the target displacement analog signals.

2. The machining tool of claim 1, wherein the at least one switch alternates which digital to analog converters release respective of the target displacement analog signals based upon the control signals.

3. The machining tool of claim 1, wherein the plurality of digital to analog converters are divided into a plurality of groups of digital to analog converters, the at least one switch comprises a plurality of switches, each of the groups corresponding to a different switch of the plurality of switches, and each switch is configured to alternate which digital to analog converter of the converters in a corresponding group of the groups release respective of the target displacement analog signals.

4. The machining tool of claim 3, wherein the second displacement mechanism comprises N actuators, each actuator of the N actuators configured to displace the cutting tool based on the target displacement analog signals, each actuator of the N actuators corresponding to a different group of the plurality of groups.

5. The machining tool of claim 4, where the actuators comprise piezoelectric actuators or voice coils.

6. The machining tool of claim 1, wherein the first displacement mechanism is configured to displace the cutting tool, based upon the control signals, in a first direction and in a second direction so as to define a number of discrete paths along the workpiece.

7. The machining tool of claim 6, wherein the workpiece support comprises a cylindrical drum, the first direction is along an angular displacement, θ

, about an axis of the drum, and the second direction is along the axis of the drum.

8. The machining tool of claim 6, wherein the workpiece support comprises a substantially planar surface, and the first direction and the second direction are substantially orthogonal to each other.

9. The machining tool of claim 6, wherein the controller further comprises a path counter unit configured to determine the current path based upon the control signals, and to inform the displacement determination unit of the current path.

10. The machining tool of claim 9, wherein the workpiece support comprises a cylindrical drum, the first direction is along an angular displacement, θ

, about an axis of the drum, the second direction is along the axis of the drum, and the discrete paths are rings.

11. The machining tool of claim 9, wherein the controller further comprises:

an optical interface configured to receive trigger signals of the control signals, the trigger signals indicating the triggering of the first displacement mechanism, convert the trigger signals to optical signals, and send the optical signals to the path counter unit.

12. The machining tool of claim 6, wherein the controller further comprises:

an nX signal multiplier/divider configured to receive the control signals, multiply the frequency of the control signals by n times in the second direction, n is a number greater than or less than 1, and pass the multiplied frequency control signals to the displacement determination unit.

13. The machining tool of claim 1, wherein the at least one switch comprises at least one gate switch.

14. The machining tool of claim 1, wherein the controller further comprises a filter buffer arranged to receive and smooth the target displacement analog signals.

15. The machining tool of claim 1, wherein the second displacement mechanism comprises at least one actuator configured to displace the cutting tool based on the target displacement analog signals.

16. The machining tool of claim 15, wherein the at least one actuator comprises N actuators, where N is an integer greater than or equal to two.

17. The machining tool of claim 16, wherein each of the N actuators is configured to displace the cutting tool in a different direction.

18. The machining tool of claim 16, wherein N is equal to two and the different directions are orthogonal to each other.

19. The machining tool of claim 1, further comprising:

a sensor unit arranged to detect the position of the cutting tool, and to provide a position signal indicative of the detected position of the cutting tool to the controller; and

wherein the controller comprises a feedback control unit arranged to receive the position signal from the sensor unit and adjust the target displacement digital signals based on the position signal.

20. The machining tool of claim 19, wherein the sensor unit comprises:

a sensor detecting a position of the cutting tool and providing an unamplified position signal; and

a sensor amplifier arranged to amplify the unamplified position signal to provide the position signal.

21. The machining tool of claim 19, wherein the feedback control unit comprises:

an analog to digital converter unit arranged to receive the position signal from the sensor unit and convert the position signal to a digital position signal; and

a feed back controller circuit arranged to receive the digital position signal and adjust the target displacement digital signal based on the digital position signal.

22. The machining tool of claim 1, wherein the displacement determination unit determines the target displacement by calculating the target displacement.

23. The machining tool of claim 22, wherein the displacement determination unit calculates the target displacement according to a displacement function.

24. The machining tool of claim 23, wherein the displacement function is defined by a first function modulated by a second function, the second function being random or pseudo random.

25. The machining tool of claim 1, wherein the displacement determination unit determines the target displacement by receiving pre-calculated target displacement values.

26. A machining tool for machining a workpiece on a workpiece support in response to control signals, comprising:

a cutting tool configured to cut a surface of the workpiece;

a first displacement mechanism arranged to displace the cutting tool relative to the workpiece in a first set of coordinates in response to control signals, the first displacement mechanism configured to displace the cutting tool in a first direction and in a second direction so as to define a number of discrete paths along the workpiece based upon the control signals, wherein the workpiece support comprises a cylindrical drum, the first direction is an angular displacement, θ

, about an axis of the drum, the second direction is along the axis of the drum, and the discrete paths are rings;

a second displacement mechanism supported by the first displacement mechanism and arranged to displace the cutting tool relative to the workpiece in a second set of coordinates; and

a controller configured to receive the control signals and synchronize the displacement of the cutting tool due to the first displacement mechanism with the displacement of the cutting tool due to the second displacement mechanism, the controller comprising;

a displacement determination unit that determines a target displacement of the cutting tool in the second set of coordinates and provides target displacement digital signals based on the determined target displacement;

a plurality of digital to analog converters configured to receive respective of the target displacement digital signals from the displacement determination unit and convert the target displacement digital signals to target displacement analog signals; and

a switch configured to alternate which digital to analog converter releases a respective of the target displacement analog signals based upon the control signals.

27. A method of machining a workpiece in response to control signals, comprising:

providing a cutting tool configured to cut a surface of the workpiece;

displacing the cutting tool relative to the workpiece in a first set of coordinates in response to the control signals using a first displacement mechanism;

displacing the cutting tool relative to the workpiece in a second set of coordinates using a second displacement mechanism the second displacement mechanism capable of a higher frequency response than the first displacement mechanism; and

synchronizing the displacement of the cutting tool in the first set of coordinates with the displacement of the cutting tool in the second set of coordinates;

wherein displacing the cutting tool relative to the workpiece in a second set of coordinates comprises;

determining a target displacement of the cutting tool in the second set of coordinates;

providing target displacement digital signals based on the determined target displacement;

converting the target displacement digital signals to target displacement analog signals using a plurality of digital to analog converters; and

switching which digital to analog converter releases a respective of the target displacement analog signals.

28. The method of claim 27, wherein the switching is based upon the control signals.

29. The method of claim 27, wherein in the displacing the cutting tool relative to the workpiece in the first set of coordinates, the cutting tool is displaced in a first direction and in a second direction so as to define a number of discrete paths along the workpiece.

30. The method of claim 27, wherein displacing the cutting tool relative to the workpiece in the first set of coordinates, the cutting tool is displaced in a first direction and in a second direction so as to define a number of discrete paths along the workpiece.

31. The method of claim 30, wherein displacing the cutting tool relative to the workpiece in the first set of coordinates and the second set of coordinate comprises making more than one pass over each discrete path, each pass over a particular path being substantially identical in displacement of the cutting tool.

32. The method of claim 31, wherein displacing the cutting tool relative to the workpiece in a second set of coordinates comprises:

calculating a target displacement of the cutting tool in the second set of coordinates according to a displacement function, wherein the displacement function is defined by a first function modulated by a second function, the second function being random or pseudo random.