Counter plate electrode with self adjusting z-axis

• US 20020134683A1
• Filed: 10/24/2001
• Published: 09/26/2002
• Est. Priority Date: 03/09/2001
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Steele, Mark G.
• Granted Patent: US 6,884,330 B2
• Time in Patent Office: Days
• US Class Current: 204/640
• CPC Class Codes: B23H 2200/10 for making bearings
• CPC Class Codes: B23H 3/00 Electrochemical machining, i.e. removing metal by passing current between an electrode and a workpiece in the presence of an electrolyte
• CPC Class Codes: B23H 3/02 Electric circuits specially adapted therefor, e.g. power supply, control, preventing short circuits
• CPC Class Codes: B23H 9/00 Machining specially adapted for treating particular metal objects or for obtaining special effects or results on metal objects heat treatment by cathodic discharge C21D1/38
• CPC Class Codes: F16C 17/107 with at least one surface for radial load and at least one surface for axial load
• CPC Class Codes: F16C 2220/68 by electrical discharge or electrochemical machining
• CPC Class Codes: F16C 2370/12 Hard disk drives or the like
• CPC Class Codes: F16C 33/107 Grooves for generating pressure
• CPC Class Codes: F16C 33/14 Special methods of manufacture; Running-in

Abstract

The present invention relates to a method and apparatus for properly and consistently spacing an electrode from a workpiece while electrochemically etching (ECM) grooves to a precise depth in a surface of the workpiece to form a fluid dynamic bearing. The electrode is especially designed for imparting a grooved pattern to a flat surface, the electrode comprising a surface carrying the pattern to be formed on the flat surface, and a central rod extending a short distance above the electrode surface. The central rod precisely sets the gap between the electrode and the flat surface. The electrode is adapted to be electrically connected to a power supply so that the electrode serves as the cathode, and the flat work piece serves as the anode in an ECM system.

Claims

1. A device for accurately forming grooves of a precise pre-selected depth on a flat surface comprising an electrode for use in an ECM (electro chemical machining system), the electrode being designed for imparting a grooved pattern to a flat surface, the electrode comprising a surface carrying the pattern to be formed on the flat surface, and a central rod extending a short distance above the electrode surface, the central rod precisely setting the gap between the electrode and the flat surface.

2. An electrode as claimed in claim 1 wherein the electrode is adapted to be electrically connected to a power supply so that the electrode serves as the cathode, and the flat work piece serves as the anode in an ECM system.

3. An electrode as claimed in claim 1 wherein the central rod is grooved threaded into the electrode so that the height of the central rod above the outer electrode can be adjusted.

4. A electrode as claimed in claim 1 wherein the outer surface of the electrode is annular in shape.

5. An electrode as claimed in claim 1 wherein a pattern to be formed on the flat surface is defined by raised lands of electrically conductive material.

6. An electrode as claimed in claim 5 wherein the raised lands of the electrically conductive material are separated by insulating material.

7. An electrode as claimed in claim 5 wherein the raised lands of the electrically conductive material are separated and surrounded by insulated material of equal height to the lens of the electrically conductive material.

8. An electrode as claimed in claim 5 wherein the center rod of the electrode comprises an electrically inert material.

9. An electrode as claimed in claim 8 wherein the center rod of the electrode comprises ceramic material.

10. An electrode as claimed in claim 7 wherein the center rod is movable axially within an outer section of the electrode.

11. A system for defining a groove pattern of a precise depth on a flat surface of a workpiece utilitizing electrochemical machining (ECM) comprising a first device for supporting the flat surface of the workpiece facing an electrode, and an electrode designed for imparting a grooved pattern to a flat surface, the electrode comprising an outer section ending in a surface carrying the pattern to be formed on the flat surface, and a central rod extending a short distance above the annular electrode surface, the central electrically inert center rod precisely setting the gap between the electrode and the flat surface.

12. A system as claimed in claim 11 comprising an inlet through said outer electrode connected to a gap between the center rod and the outer electrode, said gap extending axially to a surface of the electrode facing the flat surface so that electrolyte can be supplied to the gap defined between the electrode and the flat surface.

13. An electrode as claimed in claim 12 wherein the center rod is movable axially within an outer section of the electrode.

14. A system as defined in claim 13 including a screw threaded into a center bore in the electrode outer section and movable axially to move the center rod, thereby adjusting the gap.

15. A system as claimed in claim 14 wherein the screw is integrated with the center rod, threads being defined on the interior of the bore to position the rod.

16. A system as claimed in claim 15 wherein the center rod comprises an electrically inert material.

17. A system as claimed in claim 16 wherein a pattern to be formed on the flat surface is defined by raised lands of electrically conductive material.

18. A system as claimed in claim 17 wherein the raised lands of the electrically conductive material are separated and surrounded by insulated material of equal height to the lens of the electrically conductive material.

20. A system of claim 19 wherein the electrode means comprises an outer section ending in a surface carrying the pattern to be formed on the flat surface, and a central rod extending a short distance above the annular electrode surface, the central electrically inert center rod precisely setting the gap between the electrode and the flat surface.

19. A system for defining a groove pattern of a precise depth on a flat surface of a workpiece utilizing electrochemical machining (ECM) comprising a first device for supporting the flat surface of the workpiece facing an electrode, and electrode means facing the flat surface for imparting a grooved pattern to a flat surface.