Methods for the electroerosion machining of high-performance metal alloys

Patent metadata

Field	Value
Publication number	US-10022812-B2
Application number	US-201414510757-A
Country	US
Kind code	B2
Filing date	Oct 9, 2014
Priority date	Oct 9, 2014
Publication date	Jul 17, 2018
Grant date	Jul 17, 2018

Abstract

A method of machining a work-piece formed of titanium-based material, using a machining apparatus, is described. The method includes the steps of providing an electrically-conductive electrode contained within a spindle assembly, in a pre-selected distance and position relative to the titanium-based work-piece; while electrically powering the electrode and the work-piece with a power supply. In the process, fluid electrolyte is circulated through at least two pathways in the machining apparatus—an internal conduit within the spindle assembly; and an external conduit. The charged electrode is moved relative to the work-piece in a plunging motion, to remove material from the work-piece at a relatively high rate, using a high-speed electro-erosion (HSEE) process.

First claim

What is claimed:

1. A method of machining a work-piece formed of titanium-based material, using a machining apparatus, the method comprising:
(a) providing an electrode contained within a spindle assembly, in a pre-selected distance and position relative to the work-piece, while electrically powering the electrode and the work-piece with a power supply, wherein the electrode is electrically-conductive;
(b) circulating a fluid electrolyte through at least two pathways in the machining apparatus, wherein a first pathway comprises an internal conduit within the spindle assembly, and wherein a second pathway comprises an external conduit outside of the spindle assembly and at least partially within a gap between the electrode and the work-piece; and
(c) moving the electrode relative to the work-piece in a plunging motion, and retracting the electrode to permit removal of the titanium-based material from the work-piece using a high-speed electroerosion (HSEE) process,
wherein a total flushing pressure value of the circulating fluid electrolyte and a rotational speed of the electrode are simultaneously controlled by an automated mechanism when a measured current in the electrode exceeds a threshold current of the electrode, so as to maximize an efficiency of removal of the titanium-based material from the work-piece by reducing formation of a molten metal bridge from debris of the removed titanium-based material in the gap.

2. The method of claim 1 , wherein the electrode is rotated during the HSEE process at a linear speed in a range from about 7,000 inches per minute to about 125,000 inches per minute.

3. The method of claim 2 , wherein the linear speed is at least about 36,000 inches per minute.

4. The method of claim 2 , wherein the electrode is operated under a current density of at least about 15 amps/mm 2 .

5. The method of claim 1 , wherein the fluid electrolyte provides cooling to the work-piece and to the gap between the work-piece and the electrode, and wherein the fluid electrolyte further flushes away the debris that results from the removal of the titanium-based material from the work-piece.

6. The method of claim 5 , wherein the fluid electrolyte comprises one or more additives for increasing an electrical discharge between the work-piece and the electrode.

7. The method of claim 1 , wherein the spindle assembly is contained in a multi-axis machine or connected to the multi-axis machine, and wherein the multi-axis machine is configured to support and rotate the electrode.

8. The method of claim 7 , wherein the multi-axis machine is in operative communication with a controller configured to distribute intermittent multiple electrical arcs between the electrode and the work-piece.

9. The method of claim 1 , wherein the plunging motion is axial and perpendicular to a work-piece surface that requires removal of material.

10. The method of claim 9 , wherein the plunging motion cuts pocket holes into the work-piece surface.

11. The method of claim 1 , wherein the work-piece is a component of a turbine engine or a portion of an aircraft airframe.

12. The method of claim 1 , wherein the electrode is energized by the power supply that applies a potential difference ΔV between the work-piece and the electrode with the threshold current, the method further comprising:
(i) measuring the current at selected intervals during machining;
(ii) comparing the measured current with the threshold current to determine if the measured current indicates an out-of-control status; and
(iii) generating a control signal indicative of the out-of-control status, the control signal resulting in an adjustment of (I) an electrode rotation speed or (II) an electrolyte flushing pressure, so as to return the machining to an in-control status.

13. A method of machining a titanium-based component, in which material is removed from selected regions of the titanium-based component by using a high-speed electroerosion (HSEE) process in which an electrically-conductive electrode is controllably moved, retracted to permit removal of the material and rotated in a plunging, pocket-hole forming motion, relative to the titanium-based component; and
wherein a fluid electrolyte is circulated through both an internal pathway within the electrically-conductive electrode and an external pathway outside of the electrically-conductive electrode and within a gap between the electrically-conductive electrode and the titanium-based component, and
wherein a total flushing pressure value of the circulating fluid electrolyte and a rotational speed of the electrically-conductive electrode are simultaneously controlled by an automated mechanism when a measured current in the electrically-conductive electrode exceeds a threshold current of the electrically-conductive electrode, so as to maximize an efficiency of removal of the material from the titanium-based component by reducing formation of a molten metal bridge from debris of the removed material in the gap.

14. The method of claim 13 , wherein the electrically-conductive electrode is rotated during the HSEE process at a linear speed in a range from about 7,000 inches per minute to about 125,000 inches per minute.

15. The method of claim 14 , wherein the linear speed is at least about 36,000 inches per minute.

16. The method of claim 14 , wherein the electrically-conductive electrode is operated under a current density of at least about 15 amps/mm 2 .

17. The method of claim 13 , wherein the fluid electrolyte provides cooling to the titanium-based component and to the gap between the titanium-based component and the electrically-conductive electrode, and wherein the fluid electrolyte further flushes away the debris that results from the removal of the material from the titanium-based component.

18. The method of claim 17 , wherein the fluid electrolyte comprises one or more additives for increasing an electrical discharge between the titanium-based component and the electrically-conductive electrode.

19. The method of claim 13 , wherein the plunging is axial and perpendicular to a surface of the titanium-based component that requires removal of material.

20. The method of claim 13 , wherein the electrically-conductive electrode is energized by a power supply that applies a potential difference ΔV between the titanium-based component and the electrically-conductive electrode with the threshold current, the method further comprising:
(i) measuring the current at selected intervals during machining;
(ii) comparing the measured current with the threshold current to determine if the measured current indicates an out-of-control status; and
(iii) generating a control signal indicative of the out-of-control status, the control signal resulting in an adjustment of (I) an electrically-conductive electrode rotation speed or (II) an electrolyte flushing pressure, so as to return the machining to an in-control status.

Assignees

• Gen Electric

Inventors

• Luo Yuanfeng
• Hayashi Steven Robert
• Trimmer Andrew Lee
• Cintula Mark James

Classifications

• B23H1/10

  Supply or regeneration of working media · CPC title

• B23H7/36

  Supply or regeneration of working media · CPC title

• B23H3/04

  Electrodes specially adapted therefor or their manufacture (B23H9/00 takes precedence) · CPC title

• B23H9/10

  Working turbine blades or nozzles · CPC title

• B23H1/04

  Electrodes specially adapted therefor or their manufacture (B23H9/00 takes precedence) · CPC title