SYSTEMS AND METHODS FOR Z-HEIGHT MEASUREMENT AND ADJUSTMENT IN ADDITIVE MANUFACTURING
In some embodiments of the instant disclosure, a method is provided comprising: additively manufacturing a part via a material deposition-based additive manufacturing technique; concomitant with additively manufacturing the part, measuring a z-height of the deposition via a non-linear mathematical model to determine a measured z-height, wherein the measured z-height is a distance between an additive manufacturing system energy source and a top surface of a molten pool; comparing the measured z-height with a target z-height to identify a difference between the measured z-height and the target z-height; adjusting a motion controller to set a corrected z-height; and depositing an additive manufacturing feed material based on the corrected z-height.
1 . A method, comprising:
additively manufacturing a part via a material deposition-based additive manufacturing technique;
concomitant with additively manufacturing the part, measuring a measured z-height of the material deposition-based additive manufacturing technique via a non-linear mathematical model to determine the measured z-height, wherein the measured z-height is a distance between an additive manufacturing system energy source and a top surface of a molten pool;
comparing the measured z-height with a target z-height to identify a difference between the measured z-height and the target z-height;
adjusting a motion controller to set a corrected z-height; and
depositing an additive manufacturing feed material based on the corrected z-height.
2 . The method of claim 1 , wherein the adjusting a motion controller comprises sending a signal to the motion controller coupled to the additive manufacturing system energy source to set the corrected z-height.
3 . The method of claim 1 , wherein the non-linear mathematical model is:
Z
+
=
SD
+
h
sin
β
(
L
1
-
f
)
f
sin
α
-
h
cos
α
sin
β
Z
-
=
SD
-
h
sin
β
(
L
1
-
f
)
f
sin
α
+
h
cos
α
sin
β
wherein SD is the stand-off distance between the additive manufacturing system energy source and (i) the molten pool (ii) or a surface of a deposited material in a previous layer;
wherein h is a distance between an image point a and an image point b on a physical image sensor unit;
wherein L 1 is a distance from a lens center to the molten pool or to the surface of the deposited material in the previous layer;
wherein α is an angle between a line Aa and a direction of energy;
wherein β is an angle between the line Aa and an image sensor surface; and
wherein f is a focal length.
4 . The method of claim 3 , wherein the measured z-height is a negative value.
5 . The method of claim 4 , wherein the additive manufacturing system energy source is adjusted downward in a vertical direction toward the molten pool.
6 . The method of claim 3 , wherein the measured z-height is a positive value.
7 . The method of claim 6 , wherein the additive manufacturing system energy source is adjusted upward in a vertical direction away from the molten pool.
8 . The method of claim 1 , wherein the material deposition-based additive manufacturing technique is a wire-fed deposition technique.
9 . The method of claim 1 , wherein the material deposition-based additive manufacturing technique is an injectable fluidized powder-based deposition technique.
10 . The method of claim 1 , wherein the measured z-height is the target z-height.
11 . The method of claim 1 , wherein the measuring the z-height comprises:
taking an image of the molten pool via an imaging device;
correlating and calculating the position of the molten pool relative to the additive manufacturing system energy source via a designed non-linear mathematical model;
comparing the measured z height to the target z height;
calculating a deviation between the measured z-height and the target z-height; and
adjusting, via the motion controller, the height of the energy source relative to the top surface of the molten pool to minimize the deviation, if any, between the measured z-height and the target z-height.
12 . The method of claim 11 , wherein the imaging device is configured to measure a distance between a lowermost portion of the energy source to the top surface of the molten pool.
13 . The method of claim 11 , wherein parameters of the material deposition-based additive manufacturing technique are controlled in order to adjust the z-height.
14 . The method of claim 13 , wherein the z-height is adjusted based at least in part on adjusting a value of an E-beam power parameter.
15 . The method of claim 13 , wherein the z-height is adjusted based at least in part on adjusting a feed rate of the additive manufacturing feed material.
16 . The method of claim 1 , wherein the measured z-height is compared with the target z-height concomitantly with the additively manufacturing the part.
17 . The method of claim 1 , wherein the motion controller is adjusted to provide a corrected z-height to reduce the difference between the target z-height and the corrected z-height, concomitantly with the additively manufacturing the part.
18 . An apparatus comprising:
a substrate having a first surface configured to hold an additively manufactured part;
an energy source disposed opposite the substrate and configured to direct an energy beam toward the first surface of the substrate;
a fixture having a first end and a second end, wherein the first end is coupled to a housing of the energy source;
a sensor coupled to a second end of the fixture, wherein the sensor is configured to image light in particular wavelengths emitted by hot additive manufacturing material; and
a motion controller coupled to the energy source and configured to adjust a vertical distance from the energy source to a top surface of additively manufactured part.
19 . The apparatus of claim 18 , wherein the motion controller comprises a motion motor and a controller.