Additive manufacturing of three-dimensional articles

• US 10,525,547 B2
• Filed: 04/24/2017
• Issued: 01/07/2020
• Est. Priority Date: 06/01/2016
• Status: Active Grant

• Current Assignee: Arcam Ab (Danaher Corporation)
• Original Assignee: Arcam Ab (Danaher Corporation)
• Inventors: Ekberg, Christian
• Primary Examiner(s): Heinrich, Samuel M
• Application Number:
  US15/495,323
• Publication Number:
  US 20170348791A1
• Time in Patent Office: 988 Days
• Field of Search: 21912112-12135
• CPC Class Codes: B23K 15/0026 Auxiliary equipment
• CPC Class Codes: B23K 15/0086 welding for purposes other than joining, e.g. built-up welding
• CPC Class Codes: B23K 15/02 Control circuits therefor
• CPC Class Codes: B23K 15/06 within a vacuum chamber B23K15/04 takes precedence
• CPC Class Codes: B29C 64/153 using layers of powder being selectively joined, e.g. by selective laser sintering or melting
• CPC Class Codes: B33Y 10/00 Processes of additive manufacturing
• CPC Class Codes: B33Y 30/00 Apparatus for additive manufacturing; Details thereof or accessories therefor
• CPC Class Codes: B33Y 50/02 for controlling or regulating additive manufacturing processes
• CPC Class Codes: H01J 2237/0206 Extinguishing, preventing or controlling unwanted discharges
• CPC Class Codes: H01J 2237/06308 Thermionic sources
• CPC Class Codes: H01J 2237/06375 Arrangement of electrodes
• CPC Class Codes: H01J 2237/3128 Melting
• CPC Class Codes: H01J 3/024 Electron guns using thermionic emission of cathode heated by electron or ion bombardment or by irradiation by other energetic beams, e.g. by laser
• CPC Class Codes: H01J 3/026 Eliminating deleterious effects due to thermal effects, electric or magnetic field H01J3/021 - H01J3/025 take precedence
• CPC Class Codes: H01J 3/027 Construction of the gun or parts thereof H01J3/021 - H01J3/025, H01J3/026 and H01J3/028 take precedence
• CPC Class Codes: H01J 3/029 Schematic arrangements for beam forming
• CPC Class Codes: H01J 37/06 Electron sources; Electron guns electron sources in general H01J1/02, H01J19/02; electron guns in general H01J3/02
• CPC Class Codes: H01J 37/305 for casting, melting, evaporating or etching methods for casting or melting of metals with electron beam or gas discharges C22B9/22

Abstract

A method is provided for forming a three-dimensional article through successively depositing individual layers of powder material that are fused together so as to form the article, the method comprising the steps of: providing at least one electron beam source emitting an electron beam for at least one of heating or fusing the powder material, where the electron beam source comprises a cathode, an anode, and a Wehnelt cup between the cathode and anode; providing a guard ring between the Wehnelt cup and the anode and in close proximity to the Wehnelt cup, where the guard ring is having an aperture which is larger than an aperture of the Wehnelt cup; protecting the cathode and/or the Wehnelt cup against vacuum arc discharge energy currents when forming the three-dimensional article by providing the guard ring with a higher negative potential than the Wehnelt cup and cathode.

Claims

1. A method for forming a three-dimensional article through successively depositing individual layers of powder material that are fused together so as to form the article, the method comprising the steps of:

providing at least one electron beam source emitting an electron beam for at least one of heating or fusing the powder material, wherein the electron beam source comprises a cathode, an anode, and a Wehnelt cup positioned between the cathode and anode;

providing a guard ring between the Wehnelt cup and the anode and in close proximity to the Wehnelt cup, wherein the guard ring has an aperture larger than an aperture of the Wehnelt cup; and

protecting at least one of the cathode or the Wehnelt cup against vacuum arc discharge energy currents when forming the three-dimensional article by providing the guard ring with a higher negative potential than a negative potential of the Wehnelt cup and the cathode.

2. The method according to claim 1, wherein the guard ring potential is fixed with reference to cathode potential.

3. The method according to claim 1, wherein the guard ring potential is synchronized with the grid cup potential so that the guard ring potential is always 200-400V more negative than the grid cup potential.

4. The method according to claim 1, wherein the guard ring is connected to an electric circuit dedicated to maintain the fixed guard ring potential during the vacuum arc discharge.

5. The method according to claim 1, further comprising the step of aligning a center of an aperture in the Wehnelt cup with a center of an aperture in the guard ring.

6. The method according to claim 1, wherein one or more of the steps recited therein are computer-implemented via at least one control unit or processor.

7. A computer program product comprising at least one non-transitory computer-readable storage medium having computer-readable program code portions embodied therein, the computer-readable program code portions comprising at least one executable portion configured for:

providing at least one electron beam source emitting an electron beam for at least one of heating or fusing the powder material, wherein the electron beam source comprises a cathode, an anode, and a Wehnelt cup positioned between the cathode and anode;

providing a guard ring between the Wehnelt cup and the anode and in close proximity to the Wehnelt cup, wherein the guard ring has an aperture larger than an aperture of the Wehnelt cup; and

protecting the cathode and/or the Wehnelt cup against vacuum arc discharge energy currents when forming the three-dimensional article by providing the guard ring with a higher negative potential than a negative potential of the Wehnelt cup and the cathode.

8. The computer program product according to claim 7, wherein the at least one executable portion is configured such that the guard ring potential is fixed with reference to cathode potential.

9. The computer program product according to claim 7, wherein the at least one executable portion is configured such that the the guard ring potential is synchronized with the grid cup potential so that the guard ring potential is always 200-400V more negative than the grid cup potential.

10. The computer program product according to claim 7, wherein the guard ring is connected to an electric circuit dedicated to maintain the fixed guard ring potential during the vacuum arc discharge.

11. The computer program product according to claim 7, wherein the at least one executable portion is configured for aligning a center of an aperture in the Wehnelt cup with a center of an aperture in the guard ring.

12. An additive manufacturing apparatus for forming a three-dimensional article through successive fusion of parts of at least one layer of powder provided on a work table, which parts corresponds to successive cross sections of the three dimensional article, the apparatus comprising:

at least one electron beam source emitting an electron beam for at least one of heating or fusing the powder material, the electron beam source comprising a cathode, an anode, and a Wehnelt cup between the cathode and anode; and

a guard ring positioned between the Wehnelt cup and the anode and in close proximity to the Wehnelt cup, the guard ring having an aperture larger than an aperture of the Wehnelt cup,

wherein the guard ring is provided with a higher negative potential than the Wehnelt cup for protecting at least one of the cathode or the Wehnelt cup against vacuum arc discharge energy currents when forming the three-dimensional article.

13. The apparatus according to claim 12, wherein the guard ring is connected to an electric circuit dedicated to maintain the fixed guard ring potential during the vacuum arc discharge.

14. The apparatus according to claim 12, further comprising a synchronizing unit for synchronizing the guard ring potential with the grid cup potential so that the guard ring potential is always 200-400V more negative than the grid cup potential.

15. The apparatus according to claim 12, wherein a center of an aperture in the Wehnelt cup is aligned with a center of an aperture in the guard ring.