Additive manufacturing of three-dimensional articles

Patent metadata

Field	Value
Publication number	US-9802253-B2
Application number	US-201414547530-A
Country	US
Kind code	B2
Filing date	Nov 19, 2014
Priority date	Dec 16, 2013
Publication date	Oct 31, 2017
Grant date	Oct 31, 2017

Abstract

The present invention relates to 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 heating and/or fusing said powder material. Controlling the electron beam source in a first mode when said formation of said three dimensional article is in a first process step. Controlling said electron beam in a second mode when said formation of said three dimensional article is in a second process step, wherein in said first mode an electron beam current from said electron beam source is controlled in a feed-forward mode and in said second mode said electron beam current is controlled in a feed-back mode.

First claim

That which is claimed:

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:
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; and
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 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, and post heat treatment of an already fused powder layer;
an electron beam current from said electron beam source is controlled in a feed-forward mode in said first mode;
the first process step involves fusing said powder material;
a predetermined grid potential provided to the grid is changed, during fusion of said powder material in the first process step, from a first predetermined grid potential to a second predetermined grid potential different from the first predetermined grid potential;
said electron beam current is controlled in a feed-back mode in said second mode; and
said feed-back mode comprises measuring said electron beam current.

2. The method according to claim 1 , further comprising the steps of:
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 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 method according to claim 2 , further comprising the steps of:
comparing a first actual electron beam current with a first desired electron beam current; and
updating 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 , wherein said predetermined grid voltage is changed from the first predetermined grid voltage to the second predetermined 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.

Assignees

• Arcam Ab

Inventors

• Jonasson Daniel

Classifications

• B29K2105/251

  Particles, powder or granules (expandable particles B29K2105/046) · CPC title

• B33Y50/02

  for controlling or regulating additive manufacturing processes · CPC title

• B29C64/393

  for controlling or regulating additive manufacturing processes · CPC title

• B33Y10/00

  Processes of additive manufacturing · CPC title

• B23K15/0086

  welding for purposes other than joining, e.g. build-up welding · CPC title