Additive manufacturing of three-dimensional articles

• US 9,919,361 B2
• Filed: 03/06/2017
• Issued: 03/20/2018
• 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 S
• Application Number:
  US15/450,358
• Publication Number:
  US 20170173691A1
• Time in Patent Office: 379 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 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:

i) 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;

ii) controlling the electron beam source in at least two modes during said formation of said three dimensional article, the at least two modes comprising a first mode and a second mode;

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

iv) applying at least one of a predetermined number of different grid voltages between said grid and said cathode for producing a corresponding predetermined number of electron beam current values while the electron beam source is in the first mode;

v) while applying the at least one of the predetermined number of different grid voltages, fusing the powder material;

vi) measuring an electron beam current during the second mode of the at least two modes;

vi) 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; and

vii) subsequent to creating or updating the look-up table or mathematical function, repeating steps iv-v, wherein the at least one of the predetermined number of different grid voltages is selected from the look-up table or mathematical function.

2. The method according to claim 1, wherein:

the first mode is utilized to control the electron beam source in a first process step;

the second mode is utilized to control the electron beam source in a second process step;

said first process step is said fusion of the powder material for forming said three-dimensional article; and

said second process step is one of the group of;

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

3. The method according to claim 1, further comprising 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 method according to claim 3, wherein the updating is performed after fusing a predetermined number of layers of the three-dimensional article.

5. The method according to claim 3, wherein the updating is performed between the fusion process of each layer.

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

retrieving said predetermined grid voltage for producing said desired electron beam current from said look-up table or a mathematical function; and

changing said predetermined grid voltage from a first grid voltage to a second grid voltage during said first mode for changing said electron beam current from a first value to a second desired value during fusion of a predetermined layer.

7. The method according to claim 6, wherein said predetermined grid voltage is changed from a first grid voltage to a second grid voltage 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.