Systems and methods for modelling additively manufactured bodies

Patent metadata

Field	Value
Publication number	US-10353376-B2
Application number	US-201615011184-A
Country	US
Kind code	B2
Filing date	Jan 29, 2016
Priority date	Jan 29, 2015
Publication date	Jul 16, 2019
Grant date	Jul 16, 2019

Abstract

Methods for creating three-dimensional volume quality models of additively manufactured metal bodies are disclosed. In one embodiment, a method comprises additively manufacturing each metal layer of a metal body. One or more images of the first metal layer are obtained. The image(s) are processed to detect and map potential manufacturing defects in the first metal layer. A two-dimensional contour of the first metal layer is generated from the three-dimensional CAD model. The mapped defects are integrated into the two-dimensional contour. A first layer of a three-dimensional volume quality model of the metal body is created based on the integrated two-dimensional contour.

First claim

What is claimed is:

1. A method comprising:
(A) spreading a first layer of metal powder on a powder bed;
(B) selectively melting at least a portion of the first layer of metal powder, thereby forming a melt pool comprising molten metal of the metal powder;
(C) solidifying the molten metal into a first metal layer of a metal body;
(D) spreading a second layer of metal powder on the first metal layer;
(E) obtaining a first digital image of at least a portion of the second layer of metal powder;
wherein the first digital image has a plurality of pixels;
wherein each pixel of the plurality of pixels has a specific intensity value;

(F) translating the first digital image into a first binary image, wherein the translating comprises:
(i) determining a global average intensity value of the plurality of pixels;
(ii) resetting any specific intensity value that exceeds a threshold value to be equal to the global average intensity value;
(iii) determining a local average intensity value for said each pixel of the plurality of pixels;
(iv) subtracting the specific intensity value of said each pixel of the plurality of pixels from the local average intensity value, thereby determining a background-corrected intensity value for said each pixel of the plurality of pixels;
(v) replacing the specific intensity value of said each pixel with its determined background-corrected intensity value; and
(vi) performing a thresholding operation on the first digital image, thereby creating the first binary image;
wherein the first binary image has a plurality of binary pixels;
wherein the plurality of binary pixels comprises particles; and
wherein the particles are either drag particles or non-drag particles;

(G) filtering the non-drag particles from the first binary image, wherein the filtering comprises:
(i) performing an x-axis close operation on each of the binary pixels of the plurality of binary pixels;
(ii) removing from the first binary image all particles having a particle width below a threshold width;
(iii) removing from the first binary image all particles having a particle elongation ratio below a threshold ratio;
(iv) performing a dilation operation on the first binary image;
(v) determining the number of on-pixels in each row of the first binary image;
(vi) determining the number of particles in each row of the first binary image,
(vii) switching any of the on-pixels to off-pixels for any pixels in a row of the first binary image, where the row of the first binary image has either a number of on-pixels less than a threshold on-pixel number, or a number of particles greater than a threshold particle number;

(H) identifying all remaining particles in the first binary image as the drag particles associated with the spreading a second layer step (D);
(I) mapping the drag particles associated with the spreading a second layer step (D), wherein the mapping comprises:
(i) determining a location of each of the drag particles in the first binary images;
(ii) determining a size of each of the drag particles, wherein a total number of pixels comprising each of the drag particles is representative of the size of each respective drag particle;
(iii) mapping the location and size of each of the drag particles to a respective location in the powder bed;

(J) creating a first layer of a three-dimensional volume quality model of the metal body based at least in part on the location and size of each of the drag particles associated with the spreading a second layer step (D).

2. The method of claim 1 , wherein the creating step comprises:
generating a two-dimensional contour of the first metal layer of the metal body from a pre-designed three-dimensional model of the metal body;
integrating the location and size of each of the drag particles into the two-dimensional contour of the first metal layer; and
creating the first layer of the three-dimensional volume quality model of the metal body based at least in part on the integrated contour of the first metal layer.

3. The method of claim 2 , wherein the two-dimensional contour of the first metal layer is extracted from a (common layer interface) file, and wherein the pre-designed three-dimensional model of the metal body comprises an STL file.

4. The method of claim 1 , wherein the particles are first particles, wherein the non-drag particles are first non-drag particles, wherein the drag particles are first drag particles, and wherein the method comprises:
selectively melting at least a portion of the second layer of metal powder, thereby forming a melt pool comprising molten metal of the metal powder;
solidifying the molten metal into a second metal layer of the metal body;
spreading a third layer of metal powder on the second metal layer;
obtaining a second digital image of at least a portion of the third layer of metal powder;
translating the second digital image into a second binary image;
filtering second non-drag particles from the second binary image
identifying all remaining second particles in the second binary image as second drag particles associated with the spreading a third layer step;
mapping the second drag particles, thereby determining a location and size of each of the second drag particles associated with the spreading a third layer step;
creating a second layer of the three-dimensional volume quality model of the metal body based at least in part on the location and size of each second drag particle associated with the spreading a third layer of metal powder step.

5. The method of claim 1 , wherein the performing a thresholding operation step (F)(vi) comprises performing an interclass variance thresholding operation on the first digital image.

6. A method comprising:
(A) spreading an n th layer or of metal powder on a powder bed;
(B) selectively melting at least a portion of the n th layer of metal powder, thereby forming a melt pool comprising molten metal of the metal powder;
(C) solidifying the molten metal into an n th metal layer of a metal body;
(D) spreading an n th +1 layer of metal powder on the n th metal layer;
(E) obtaining an n th digital image of at least a portion of the n th +1 layer of metal powder;
(F) first translating the n th digital image into an n th primary binary image via a moment-preserving thresholding operation;
wherein the n th primary binary image has a first n th plurality of particles comprising on-pixels;

(G) second translating the n th digital image into an n th alternate binary image via a predetermined thresholding operation;
wherein the n th alternate binary image has a second n th plurality of particles comprising on-pixels;

(H) filtering non-super-elevation particles from the n th alternate binary image, wherein the filtering comprises:
(i) removing from the n th alternate binary image all particles having a number of the on-pixels less than a threshold number of on-pixels, thereby creating an n th filtered binary image;

(I) multiplying the n th primary binary image with the n th filtered binary image, thereby creating an n th multiplied binary image;
wherein the n th multiplied binary image has a third n th plurality of particles comprising on-pixels;

(J) identifying the third n th plurality of particles as super-elevation particles associated with the selectively melting step (B);
(K) mapping the super-elevation particles, wherein the mapping comprises:
(i) determining a location of each of the super-elevation particles in the first multiplied binary image;
(ii) determining a size of each of the super-elevation particles in the n th multiplied binary image, wherein a total number of the on-pixels of the n th multiplied binary image comprising each of the super-elevation particles is representative of th

Assignees

• Alcoa Inc
• Arconic Inc

Inventors

• Huang Wei
• Globig Michael A
• Siemon John
• Speer Robert J

Classifications

• G06T2207/30136

  Metal · CPC title

• G06T2207/10048

  Infrared image · 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