Additive manufacturing of three-dimensional articles

• US 10,610,930 B2
• Filed: 11/07/2016
• Issued: 04/07/2020
• Est. Priority Date: 11/18/2015
• Status: Active Grant

• Current Assignee: Arcam Ab (Danaher Corporation)
• Original Assignee: Arcam Ab (Danaher Corporation)
• Inventors: Nordkvist, Johan, Ackelid, Ulf
• Primary Examiner(s): Zhu, Weiping
• Application Number:
  US15/344,732
• Publication Number:
  US 20170136542A1
• Time in Patent Office: 1,247 Days
• Field of Search: 419 53
• CPC Class Codes: B22F 10/10 Formation of a green body
• CPC Class Codes: B22F 10/28 Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM]
• CPC Class Codes: B22F 10/30 Process control
• CPC Class Codes: B22F 10/36 of energy beam parameters
• CPC Class Codes: B22F 10/364 for post-heating, e.g. remelting
• CPC Class Codes: B22F 12/00 Apparatus or devices specially adapted for additive manufacturing; Auxiliary means for additive manufacturing; Combinations of additive manufacturing apparatus or devices with other processing apparatus or devices
• CPC Class Codes: B22F 12/41 characterised by the type, e.g. laser or electron beam
• CPC Class Codes: B22F 12/45 Two or more
• CPC Class Codes: B22F 12/55 Two or more means for feeding material
• CPC Class Codes: B22F 2203/11 temperature, temperature profile
• CPC Class Codes: B22F 2998/10 Processes characterised by the sequence of their steps
• CPC Class Codes: B22F 2999/00 Aspects linked to processes or compositions used in powder metallurgy
• CPC Class Codes: B22F 3/1017 Multiple heating or additional steps B22F3/101 takes precedence
• 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: B29C 64/153 using layers of powder being selectively joined, e.g. by selective laser sintering or melting
• CPC Class Codes: B29C 64/386 Data acquisition or data processing for additive manufacturing
• CPC Class Codes: B29C 64/393 for controlling or regulating additive manufacturing processes
• 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: Y02P 10/25 : Process efficiency

Abstract

The present invention relates to a methods, computer program products, program elements, and apparatuses 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 and an anode, and varying an accelerator voltage between the cathode and the anode between at least a first and second predetermined value during the forming of the three-dimensional article.

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, where the electron beam source comprises a cathode and an anode,

varying an accelerator voltage between the cathode and the anode between at least a first and a second predetermined value during the forming of the three-dimensional article,

applying the first predetermined value of the accelerator voltage between the cathode and the anode when the formation of the three dimensional article is in a first stage, and

applying the second predetermined value of the accelerator voltage between the cathode and the anode when the formation of the three dimensional article is in a second stage, wherein the predetermined first value of the accelerator voltage differs from the second predetermined value of the accelerator voltage by at least 10 kV;

wherein;

the first stage is a first process step used for fusion of inner areas of the three dimensional article and the second stage is a second process step used for fusion of a contour of the three-dimensional article;

the first stage is a first process step used for forming solid structures and the second stage is a second process step used for net structures;

the first stage is a first process step used for first type of microstructures and the second stage is a second process step used for second type of microstructures;

the first stage is a first process step used for a central melting spot and the second stage is a second process step used for at least one surrounding heating spot;

the first stage is a first process step used for a central melting spot and the second stage is a second process step used for a concentric heating spot;

or

the first stage is a first process step used for a central melting spot and the second stage is a second process step used for an at least partially overlapping heating spot.

2. The method according to claim 1, wherein the first predetermined value of the accelerator voltage differs from the second predetermined value of the accelerator voltage by at least 25 kV.

3. The method according to claim 1, wherein the first predetermined value of the accelerator voltage differs from the second predetermined value of the accelerator voltage by at least 50 kV.

4. The method according to claim 1, wherein at least one of the first or the second accelerator voltage between the cathode and the anode is varied as a function of a deflection angle of the electron beam.

5. The method according to claim 4, wherein the function is at least one of a group consisting of:

a linear function, a polynomial function, or an exponential function.

6. The method according to claim 1, wherein at least one of the first or the second accelerator voltage between the cathode and the anode is varied as a function of a thickness of an already fused three-dimensional article.

7. The method according to claim 6, wherein the thickness of the already fused three-dimensional article is a thickness directly below a spot of the electron beam on the layer of powder.

8. The method according to claim 6, wherein the thickness is the thickness of the total number of powder layers which have been fused.

9. The method according to claim 6, wherein the thickness is the uninterrupted total thickness of powder layers which have been homogenously fused together.

10. The method according to claim 1, wherein at least one scan line comprises the first and second predetermined accelerator voltages.

11. The method according to claim 1, further comprising the steps of:

providing the first predetermined accelerator voltage at a first position and the second predetermined accelerator voltage at a second position, where the first and second positions are laterally separated from each other in a single layer of the three-dimensional article; and

switching on and off the electron beam at least once at the first and second positions.

12. The method according to claim 11, wherein a frequency of switching on and off the electron beam is either constant or varied.

13. The method according to claim 1, wherein:

the at least one electron beam source comprises a first electron beam source and a second electron beam source;

the first accelerator voltage emanates from the first electron beam source; and

the second accelerator voltage emanates from the second electron beam source.

14. The method according to claim 13, wherein:

the first accelerator voltage emanates from the first electron beam source for a first predetermined period of time;

the second accelerator voltage emanates from the second electron beam source for a second predetermined period of time; and

the first and second predetermined periods of time are non-overlapping.

15. The method according to claim 14, further comprising the steps of:

providing the first predetermined accelerator voltage at a first position during the first predetermined period of time;

providing the second predetermined accelerator voltage at a second position during the second predetermined period of time; and

switching on and off the electron beams at least once at each of the first and second positions.

16. The method according to claim 15, wherein the first and second positions are laterally separated from each other in a single layer of the three-dimensional article.

17. The method according to claim 15, wherein a frequency of the switching on and off of the electron beam is either constant or varied.

18. The method according to claim 1, wherein:

one of the first or the second accelerator voltage between the cathode and the anode is varied as a function of a deflection angle of the electron beam; and

the other of the first or the second accelerator voltage between the cathode and the anode is varied as a function of a thickness of an already fused three-dimensional article.

19. The method according to claim 1, wherein:

the electron beam source further comprises a grid; and

the grid voltage is synchronously varied with the accelerator voltage between the cathode and the anode, as such is varied between at least the first and the second predetermined value during the forming of the three-dimensional article.

20. The method according to claim 1, wherein:

the first stage is a first process step used for a central melting spot and the second stage is a second process step used for a concentric heating spot; and

the first predetermined value of the accelerator voltage is less than 2 kV.

21. The method according to claim 1, wherein:

the first stage is a first process step used for a central melting spot and the second stage is a second process step used for an at least partially overlapping heating spot; and

the first predetermined value of the accelerator voltage is less than 2 kV.

22. 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, where the electron beam source comprises a cathode and an anode,

varying an accelerator voltage between the cathode and the anode between at least a first and a second predetermined value during the forming of the three-dimensional article,

applying the first predetermined value of the accelerator voltage between the cathode and the anode when the formation of the three dimensional article is in a first stage, and

applying the second predetermined value of the accelerator voltage between the cathode and the anode when the formation of the three dimensional article is in a second stage, wherein

the predetermined first value of the accelerator voltage differs from the second predetermined value of the accelerator voltage by at least 10 kV,

the at least one electron beam source comprises a first electron beam source and a second electron beam source;

the first accelerator voltage emanates from the first electron beam source;

the second accelerator voltage emanates from the second electron beam source; and

at least one scan line comprises the first and second predetermined accelerator voltages; and

wherein;

the first stage is a first process step used for fusion of inner areas of the three dimensional article and the second stage is a second process step used for fusion of a contour of the three-dimensional article;

the first stage is a first process step used for forming solid structures and the second stage is a second process step used for net structures;

the first stage is a first process step used for first type of microstructures and the second stage is a second process step used for second type of microstructures;

the first stage is a first process step used for a central melting spot and the second stage is a second process step used for at least one surrounding heating spot;

the first stage is a first process step used for a central melting spot and the second stage is a second process step used for a concentric heating spot;

or

the first stage is a first process step used for a central melting spot and the second stage is a second process step used for an at least partially overlapping heating spot.

23. The method according to claim 22, wherein:

the first predetermined value of the accelerator voltage is less than 2 kV.

24. The method according to claim 23, wherein a switching frequency between the first and the second predetermined values of the accelerator voltage is variable as a function of scanning speed.