Additive manufacturing of three-dimensional articles

• US 10,099,289 B2
• Filed: 01/31/2018
• Issued: 10/16/2018
• Est. Priority Date: 12/16/2013
• Status: Active Grant

• Current Assignee: Arcam Ab (Danaher Corporation)
• Original Assignee: Arcam Ab (Danaher Corporation)
• Inventors: Jonasson, Daniel
• Primary Examiner(s): Dunn, Colleen P
• Assistant Examiner(s): Bajwa, Rajinder
• Application Number:
  US15/885,205
• Publication Number:
  US 20180154444A1
• Time in Patent Office: 258 Days
• CPC Class Codes: B22F 10/28 Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM]
• CPC Class Codes: B22F 10/362 for preheating
• CPC Class Codes: B22F 10/364 for post-heating, e.g. remelting
• CPC Class Codes: B23K 15/0086 welding for purposes other than joining, e.g. built-up welding
• CPC Class Codes: B28B 1/001 Rapid manufacturing of 3D objects by additive depositing, agglomerating or laminating of material selective deposition modelling of metallic powder B22F10/00; rapid manufacturing of 3D objects in general and in particular of plastics B29C64/00
• 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 64/393 for controlling or regulating additive manufacturing processes
• CPC Class Codes: B29K 2105/251 Particles, powder or granules expandable particles B29K2105/046
• CPC Class Codes: B33Y 10/00 Processes of additive manufacturing
• CPC Class Codes: B33Y 50/02 for controlling or regulating additive manufacturing processes
• CPC Class Codes: Y02P 10/25 Process efficiency

Abstract

Provided is a method for forming a three dimensional article comprising the steps of: providing at least one electron beam source emitting an electron beam for at least one of heating or fusing said powder material, where said electron beam source comprises a cathode, an anode, and a grid between said cathode and anode; controlling the electron beam source in at least two modes during said formation of said three dimensional article; applying a predetermined accelerator voltage between said cathode and said anode; applying a predetermined number of different grid voltages between said grid and said cathode for producing a corresponding predetermined number of electron beam currents; and at least one of creating or updating a look-up table or mathematical function during one of the at least two modes, wherein said look-up table or mathematical function defines a relationship between a desired electron beam current and an applied grid voltage.

Claims

1. A program element stored on a non-transitory computer readable medium, the program element being configured and arranged when executed on a computer to implement 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, said method comprising the steps of:

providing at least one electron beam source emitting an electron beam for at least one of heating or fusing said powder material, where said electron beam source comprises a cathode, an anode, and a grid between said cathode and anode;

controlling the electron beam source in a first mode when said formation of said three-dimensional article is in a first process step, wherein the first mode comprises a feed-forward mode and the first process step comprises fusing said powder material;

during the fusion of said powder material, changing a predetermined grid potential from a first predetermined grid potential to a second predetermined grid potential that is different from the first predetermined grid potential;

controlling said electron beam source in a second mode when said formation of said three dimensional article is in a second process step, wherein the second mode comprises a feed-back mode and the second process step comprises one of the group of;

preheating the surface prior to applying a new powder layer onto said surface, preheating a new powder layer, preheating a powder distribution, or post heat treatment of an already fused powder layer; and

while operating in the feed-back mode, measuring an electron beam current.

2. The program element according to claim 1, wherein the method implemented further comprises the steps of:

applying a predetermined accelerator voltage between said cathode and said anode;

applying a predetermined number of different grid potentials between said grid and said cathode for producing a corresponding predetermined number of electron beam currents; and

at least one of creating or updating a look-up table or mathematical function during said second mode wherein said look-up table or mathematical function defines a relationship between a desired electron beam current and an applied grid voltage.

3. The program element according to claim 2, wherein the method implemented further comprises the steps of:

comparing a first actual electron beam current with a first desired electron beam current; and

updating the at least one of the look-up table or mathematical function if the difference between said first actual and first desired electron beam currents is greater than a predetermined value.

4. The program element according to claim 3, wherein the updating is performed after fusing a predetermined number of layers of the three-dimensional article.

5. The program element according to claim 3, wherein the updating is performed between the fusion of each layer of the three-dimensional article.

6. The program element according to claim 3, wherein the method implemented further comprises the step of retrieving the first predetermined potential from the at least one of the look-up table or mathematical function.

7. The program element of claim 1, wherein said predetermined grid potential is changed from the first predetermined grid potential to the second predetermined grid potential during fusion of at least one individual scan line for changing said electron beam current in said scan line from a first value to a second desired value.

8. The program element of claim 1, further comprising the steps of:

applying a predetermined number of different grid potentials between said grid and said cathode for producing a corresponding predetermined number of electron beam currents; and

at least one of creating or updating a look-up table or mathematical function during the second mode of the at least two modes based on the measured electron beam current, wherein said look-up table or mathematical function defines a relationship between a desired electron beam current and an applied grid voltage.

9. 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:

controlling an electron beam source in a first mode when formation of a three dimensional article is in a first process step, wherein the electron beam source emits an electron beam for at least one of heating or fusing individual layers of a powder material together so as to form said three-dimensional article, the electron beam source comprising a cathode, an anode, and a grid between said cathode and anode and wherein the first process step comprises fusing said powder material and;

during the fusion of said powder material, changing a predetermined grid potential from a first predetermined grid potential to a second predetermined grid potential that is different from the first predetermined grid potential;

controlling said electron beam source in a second mode when said formation of said three dimensional article is in a second process step, wherein an electron beam current from said electron beam source is controlled in a feed-forward mode in said first mode and said electron beam current is controlled in a feed-back mode in said second mode; and

while operating in the feed-back mode, measuring said electron beam current.

10. The computer program product of claim 9, wherein the at least one executable portion is further configured for:

applying a predetermined accelerator voltage between said cathode and said anode;

applying a predetermined number of different grid potentials between said grid and said cathode for producing a corresponding predetermined number of electron beam currents; and

at least one of creating or updating a look-up table or mathematical function during said second mode wherein said look-up table or mathematical function defines a relationship between a desired electron beam current and an applied grid voltage.

11. The computer program product of claim 10, wherein the at least one executable portion is further configured for:

comparing a first actual electron beam current with a first desired electron beam current; and

updating the at least one of the look-up table or mathematical function if the difference between said first actual and first desired electron beam currents is greater than a predetermined value.

12. The computer program product of claim 11, wherein the updating is performed after fusing a predetermined number of layers of the three-dimensional article.

13. The computer program product of claim 11, wherein the updating is performed between the fusion of each layer of the three-dimensional article.

14. The computer program product of claim 11, wherein the at least one executable portion is further configured for retrieving the first predetermined grid potential from the at least one of the look-up table or mathematical function.

15. The computer program product of claim 9, said predetermined grid potential is changed from the first predetermined grid potential to the second predetermined grid potential during fusion of at least one individual scan line for changing said electron beam current in said scan line from a first value to a second desired value.

16. The computer program product of claim 9, wherein the at least one executable portion is further configured for:

applying a predetermined number of different grid potentials between said grid and said cathode for producing a corresponding predetermined number of electron beam currents; and

at least one of creating or updating a look-up table or mathematical function during the second mode of the at least two modes based on the measured electron beam current, wherein said look-up table or mathematical function defines a relationship between a desired electron beam current and an applied grid voltage.