Powder flow measurement in additive manufacturing systems

1 . An additive manufacturing system comprising:

a powder delivery device configured to direct a powder stream toward a build surface of a component, wherein the powder delivery device defines a longitudinal axis oriented toward the build surface; and

a powder flow monitoring system comprising:

an illumination device configured to illuminate at least some powder of the powder stream between the powder delivery device and the build surface in an image plane that is orthogonal to and intersects the longitudinal axis; and

an imaging device configured to image the illuminated powder at the image plane,

wherein the illumination device and the imaging device are positioned orthogonal to the longitudinal axis.

2 . The additive manufacturing system of claim 1 , wherein the illumination device and the imaging device are carried by an adjustable z-stage configured to move the illumination device and the imaging device parallel to the longitudinal axis relative to the powder delivery device.

3 . The additive manufacturing system of claim 2 , wherein moving the illumination device and the imaging device parallel to the longitudinal axis relative to the powder delivery device moves the image plane parallel to the longitudinal axis relative to the powder stream.

4 . The additive manufacturing system of claim 1 , wherein the powder flow monitoring system further comprises a housing configured to enclose the illumination device and the imaging device.

5 . The additive manufacturing system of claim 4 , further comprising a cooling fluid circuit, wherein the housing comprises a portion of the cooling fluid circuit.

6 . The additive manufacturing system of claim 4 , wherein the housing comprises a first view port configured to pass light from the illumination device from within the housing to outside the housing and a second view port configured to pass light from outside the housing to the imaging device.

7 . The additive manufacturing system of claim 4 , wherein the housing is configured to position and retain the illumination device and the imaging device in a fixed relationship relative to each other.

8 . The additive manufacturing system of claim 1 , wherein the illumination device comprises a laser configured to output a plane of light having a width sufficient to illuminate an entire width of the powder stream.

9 . The additive manufacturing system of claim 1 , wherein the imaging device comprises a high speed camera with a frame rate of at least 1000 frames per second.

10 . The additive manufacturing system of claim 1 , further comprising an energy delivery device configured to deliver energy to the build surface of the component to form a melt pool, and wherein the powder delivery device is configured to direct the powder stream toward the melt pool.

11 . A method comprising:

directing, by a powder delivery device, a powder stream toward a build surface of a component, wherein the powder delivery device defines a longitudinal axis oriented toward the build surface;

illuminating, by an illumination device of a powder flow monitoring system, at least some powder of the powder stream between the powder delivery device and the build surface in an image plane that is orthogonal to and intersects the longitudinal axis; and

imaging, by an imaging device of the powder flow monitoring system, the illuminated powder at the image plane, wherein the illumination device and the imaging device are positioned orthogonal to the longitudinal axis.

12 . The method of claim 11 , further comprising:

moving, by an adjustable z-stage, the illumination device and the imaging device parallel to the longitudinal axis relative to the powder delivery device to move the image plane parallel to the longitudinal axis relative to the powder stream.

13 . The method of claim 11 , wherein the powder flow monitoring system further comprises a housing configured to enclose the illumination device and the imaging device.

14 . The method of claim 13 , further comprising cooling an interior of the housing using a cooling fluid circuit.

15 . The method of claim 13 , wherein the housing comprises a first view port configured to pass light from the illumination device from within the housing to outside the housing and a second view port configured to pass light from outside the housing to the imaging device.

16 . The method of claim 13 , wherein the housing is configured to position and retain the illumination device and the imaging device in a fixed relationship relative to each other.

17 . The method of claim 11 , wherein illuminating the powder stream comprises illuminating an entire width of the powder stream using a laser configured to output a plane of light having a width sufficient to illuminate the entire width of the powder stream.

18 . The method of claim 11 , wherein imaging the illuminated powder comprises imaging the illuminated powder using a high speed camera with a frame rate of at least 1000 frames per second.

19 . The method of claim 11 , further comprising delivering, using an energy delivery device, energy to the build surface of the component to form a melt pool, and wherein directing the powder stream toward the build surface of the component comprises directing the powder stream toward the melt pool.

20 . The additive manufacturing system of claim 1 , further comprising a computing device configured to:

receive, from the imaging device, image data representative of the imaged illuminated powder; and

determine a powder mass flow based on the image data.