Electrical discharge machining system including in-situ tool electrode

Patent metadata

Field	Value
Publication number	US-10870159-B2
Application number	US-201715802312-A
Country	US
Kind code	B2
Filing date	Nov 2, 2017
Priority date	Nov 2, 2017
Publication date	Dec 22, 2020
Grant date	Dec 22, 2020

Abstract

An additive manufactured workpiece includes one or more cavities having an inner surface. A dielectric interface is formed in the cavity, and conforms to the inner surface. The additive manufactured workpiece further includes an in-situ electrode in the cavities. The dielectric interface is interposed between the in-situ electrode and the inner surface of the workpiece.

First claim

What is claimed is:

1. A method of improving an internal surface topography of a manufactured workpiece, the method comprising:
forming a dielectric interface in at least one cavity of the workpiece;
depositing graphite particles to form an in-situ electrode that is in-situ with the at least one cavity such that the dielectric interface is between the in-situ electrode located in the at least one cavity of the workpiece and a rough inner surface of the at least one cavity;
flowing an electrical current through the in-situ electrode;
inducing an electrical discharge across the dielectric interface; and
removing irregularities from the rough surface via the electrical discharge across the dielectric interface so as to convert the rough surface into a smoothened inner surface having a reduced number of irregularities.

2. The method of claim 1 , wherein removing the irregularities includes continuing to direct the electrical discharge toward the rough inner surface until the number of irregularities is below a threshold value.

3. The method of claim 2 , wherein the irregularities include a plurality of raised bumps extending from the rough inner surface along an axis that is normal with respect to the rough inner surface.

4. The method of claim 1 , wherein forming the dielectric interface comprises:
forming a conformal dielectric film in the at least one cavity to line the rough inner surface; and
prior to contacting the in-situ electrode with an electrically conductive tool electrode that generates the electrical current, forming the in-situ electrode in the at least one cavity such that the conformal dielectric film is interposed between the in-situ electrode and the rough inner surface.

5. The method of claim 4 , wherein forming the conformal dielectric film comprises:
depositing a fluid-swelling porous film into the at least one cavity, the fluid-swelling porous film conforming to the rough inner surface; and
delivering a dielectric fluid to the fluid-swelling porous film such that the dielectric fluid is absorbed therein to form the dielectric interface.

6. The method of claim 5 , wherein the dielectric fluid includes a fluid that contains a dielectric material and includes at least one of a liquid hydrocarbon, a silicone oil, ethylene glycol, propylene glycol, polyethylene glycol, glycerol, and deionized water.

7. The method of claim 6 , wherein the fluid-swelling porous film is composed of a polymer material, the polymer material including at least one of hydrophobic polymers, hydrophilic polymers, and polymer gels.

8. The method of claim 1 , wherein forming the graphite in-situ electrode comprises:
depositing a suspension containing graphite particles in the at least one cavity; and
evaporating the suspension while maintaining the graphite particles in the at least one cavity to form the in-situ electrode.

9. The method of claim 1 , wherein forming the graphite in-situ electrode comprises filing the at least one cavity with a dry graphite powder.

10. The method of claim 9 , further comprising pressuring the dry graphite powder, and injecting the pressurized dry graphite powder into the cavity to form the in-situ electrode.

11. The method of claim 1 , wherein inducing the electrical discharge across the dielectric interface comprises:
generating an electrical potential across the in-situ electrode;
inducing an electrical current through the in-situ electrode via the electrical potential; and
inducing the electrical discharge across the dielectric interface via the electrical current.

12. The method of claim 11 , wherein generating the electrical potential comprises:
prior to generating the electrical potential using an electrically conductive tool electrode, forming the in-situ electrode directly on the dielectric interface;
after forming the in-situ electrode directly on the dielectric interface, contacting the electrically conductive tool electrode against the in-situ electrode;
forming a cathode terminal on the tool electrode;
forming an anode terminal on the workpiece; and
generating a voltage across the cathode terminal and the anode terminal.

13. The method of claim 11 , wherein generating the electrical potential comprises:
forming a cathode terminal directly on the in-situ electrode;
forming an anode terminal on the workpiece; and
generating a voltage across the cathode terminal and the anode terminal.

Assignees

• Hamilton Sundstrand Corp
• Hamilton Sunstrand Corp

Inventors

• Jaworowski Mark R
• Karlen Eric W
• Lomasney Gary M
• Mironets Sergey

Classifications

• B22F10/00

  Additive manufacturing of workpieces or articles from metallic powder (apparatus or devices therefor B22F12/00) · CPC title

• B23H7/32

  Maintaining desired spacing between electrode and workpiece {, e.g. by means of particulate material} · CPC title

• B23H9/14

  Making holes · CPC title

• Y02P10/25

  Process efficiency · CPC title

• B22F2003/247

  Removing material: carving, cleaning, grinding, hobbing, honing, lapping, polishing, milling, shaving, skiving, turning the surface · CPC title