US 12,441,056 B2
Methods and associated controllers for apparatus for the layer-by-layer formation of three-dimensional objects
Gianluca Dorini, London (GB)
Assigned to Stratasys Powder Production Ltd., Nottingham (GB)
Appl. No. 17/920,677
Filed by Stratasys Powder Production Ltd., London (GB)
PCT Filed Apr. 22, 2021, PCT No. PCT/GB2021/050963
§ 371(c)(1), (2) Date Oct. 21, 2022,
PCT Pub. No. WO2021/214465, PCT Pub. Date Oct. 28, 2021.
Claims priority of application No. 2006088 (GB), filed on Apr. 24, 2020.
Prior Publication US 2023/0191694 A1, Jun. 22, 2023
Int. Cl. B29C 64/165 (2017.01); B22F 10/28 (2021.01); B22F 10/31 (2021.01); B22F 12/46 (2021.01); B22F 12/90 (2021.01); B29C 64/153 (2017.01); B29C 64/264 (2017.01); B29C 64/393 (2017.01); G01J 5/80 (2022.01); B33Y 10/00 (2015.01); B33Y 30/00 (2015.01); B33Y 50/02 (2015.01)
CPC B29C 64/165 (2017.08) [B22F 10/28 (2021.01); B22F 10/31 (2021.01); B22F 12/46 (2021.01); B22F 12/90 (2021.01); B29C 64/153 (2017.08); B29C 64/264 (2017.08); B29C 64/393 (2017.08); G01J 5/80 (2022.01); B33Y 10/00 (2014.12); B33Y 30/00 (2014.12); B33Y 50/02 (2014.12)] 20 Claims
OG exemplary drawing
 
1. A method for determining a set point for measurements from a temperature sensor of an apparatus for the layer-by-layer formation of a three-dimensional object from particulate material, the apparatus having a moveable heat source, the method comprising:
(a) distributing a calibration layer of particulate material over a build bed surface;
(b) selectively applying absorption-modifying fluid to a reference area or to an area surrounding a reference area, on the build bed surface;
(c) lowering the build bed surface to a calibration depth, wherein the moveable heat source is moveable across the build bed surface, and wherein the calibration depth defines a calibration distance D between the moveable heat source and the build bed surface greater than a build depth at which the object is built;
(d) applying heat to the reference area using the moveable heat source while measuring, using the temperature sensor, the temperature increase of a sub-reference area comprised within the reference area over a duration of time, at least until the particulate material of the reference area begins to fuse; and/or taking optical readings, using an optical sensor, of an optical property of the sub-reference area over the duration of time;
(e) determining the onset of fusion of the particulate material from the measured temperature increase and/or from a change in the optical property over the duration of time of the reference area; and
(f) applying the onset of fusion as the set point for subsequent temperature measurements of the temperature sensor.
 
14. A method for calibrating the measurement of a temperature sensor of an apparatus for the layer-by-layer formation of a three-dimensional object from particulate material, the method comprising:
(a) distributing a base layer of particulate material to form the build bed surface;
(b) applying radiation-absorbing fluid to a base reference area comprised in the base layer;
(c) fusing the particulate material of the base reference area using a heat source to form a fused base reference area;
(d) distributing a layer of particulate material over the base layer to form the build bed surface, including a reference area coincident with the base reference area;
(e) lowering the build bed surface to a calibration depth, the calibration depth defining a calibration distance D between a moveable heat source and the build bed surface that is greater than a build depth at which the object is built;
(f) operating the moveable heat source above the build bed surface to apply heat to the build bed surface while measuring, using the temperature sensor, the temperature increase of a sub-reference area comprised within the reference area over time, at least until the particulate material of the sub-reference area begins to fuse, and/or taking optical readings, using an optical sensor, of an optical property of the sub-reference area over the duration of time;
(g) determining the onset of fusion of the particulate material from the measured temperature increase over time across the sub-reference area, or where an optical sensor is used in step (f), determining the onset of fusion from the optical readings; and
(h) applying the onset of fusion as determined in step (g) as a set point for subsequent temperature measurements of the temperature sensor.
 
20. A controller configured to carry out a calibration routine based on the onset of fusion of particulate material, for an apparatus for the manufacture of a three-dimensional object by layer-by-layer deposition of particulate material over the surface of a build bed, the controller being configured to:
(a) receive data defining a reference area, within the build bed surface, of unfused particulate material;
(b) control a distributor to distribute a calibration layer of particulate material over the build bed to form the build bed surface;
(c) control a build bed height controller to lower the build bed surface to a calibration depth greater than a build depth at which the object is built;
(d) control a moveable heat source, moveable across the build bed surface, to heat the reference area for a duration of time at least until a sub-reference area comprised within the reference area begins to fuse;
(e) over the duration of time, receive temperature measurements of the sub-reference area from a temperature sensor, and/or receive optical readings of an optical property from an optical sensor of the sub-reference area;
(f) determine from the temperature measurements or the optical readings taken over the duration of time the onset of fusion, and
(g) apply the onset of fusion as the set point for subsequent temperature measurements of the temperature sensor.