ADDITIVE MANUFACTURING TEMPERATURE CONTROLLER/SENSOR APPARATUS AND METHOD OF USE THEREOF

• US 20150268099A1
• Filed: 03/23/2015
• Published: 09/24/2015
• Est. Priority Date: 03/24/2014
• Status: Active Grant

• Current Assignee: James Eldon Craig, Thomas Ross Wakeman
• Original Assignee: James Eldon Craig, Thomas Ross Wakeman
• Inventors: Craig, James Eldon, Wakeman, Thomas Ross
• Granted Patent: US 10,207,363 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B23K 2103/08 Non-ferrous metals or alloys
• CPC Class Codes: B23K 26/034 Observing the temperature of the workpiece
• CPC Class Codes: B29C 64/135 the energy source being concentrated, e.g. scanning lasers or focused light sources
• CPC Class Codes: B29C 64/393 for controlling or regulating additive manufacturing processes
• CPC Class Codes: B33Y 10/00 Processes of additive manufacturing
• CPC Class Codes: B33Y 30/00 Apparatus for additive manufacturing; Details thereof or accessories therefor
• CPC Class Codes: B33Y 50/02 for controlling or regulating additive manufacturing processes
• CPC Class Codes: G01J 2005/106 Arrays
• CPC Class Codes: G01J 2005/607 on two separate detectors
• CPC Class Codes: G01J 5/0003 for sensing the radiant heat transfer of samples, e.g. emittance meter
• CPC Class Codes: G01J 5/004 by molten metals
• CPC Class Codes: G01J 5/602 using selective, monochromatic or bandpass filtering

Abstract

An additive manufacturing temperature controller/temperature sensor uses one or more spectrophotometric sensors to monitor temperature of successive layers and preferably localized sections of successive layers of a melt pool, and transients thereof, of an object being generated for the purpose of dynamic control of the additive manufacturing device and/or quality control of the generated object manufactured with the additive manufacturing device. Generally, the additive manufacturing temperature controller/sensor apparatus monitors temperature of a section of the object during manufacture as a function of wavelength, time, position, and/or angle to determine melt extent in terms of radius and/or depth.

Claims

1. An apparatus for calculating a temperature of an object under construction, comprising:

an additive manufacturing device, comprising;

a working platform configured to hold the object under construction;

a first temperature sensor, comprising;

a first two-dimensional detector array imaging a first plane parallel to a working surface of the working platform, said first two-dimensional detector array configured to generate a first set of signals;

a second two-dimensional array of detectors imaging the first plane, said second two-dimensional detector array configured to generate a second set of signals; and

a controller configured to calculate at least a first temperature using said first set of signals and said second set of signals.

2. The apparatus of claim 1, further comprising:

a beam splitter configured to split collected light, emitted from the object, into a first beam path and a second beam path;

a first optic positioned in the first beam path between said beam splitter and said first two-dimensional detector array;

a second optic positioned in the second beam path between said beam splitter and said second two-dimensional detector array.

3. The apparatus of claim 2, further comprising:

an achromatic lens optically positioned between the object and said beam splitter.

4. The apparatus of claim 3, wherein said first optic comprises a first bandpass filter configured to transmit light in a region within:

(1) a wavelength of maximum blackbody emission intensity of a site of the object irradiated by a laser of said additive manufacturing device within a prior ten seconds and (2) a high frequency side of the wavelength.

5. The apparatus of claim 3, wherein said first optic comprises a first bandpass filter, wherein said second optic comprises a second bandpass filter, wherein regions of at least fifty percent transmittance within a bandpass wavelength range of said first bandpass filter are outside wavelengths passed by said second bandpass filter and within two hundred nanometers of wavelengths passed by said second bandpass filter.

6. The apparatus of claim 2, wherein said first optic comprises a bandpass filter configured to transmit light in a sub-region within:

(1) a wavelength of maximum blackbody emission intensity of the object irradiated by a laser of said additive manufacturing device within a prior ten seconds and (2) a low frequency side of the wavelength.

7. The apparatus of claim 3, said beam splitter comprising:

a first diagonal half of a glass cube comprising a first volume diagonal face;

a second diagonal half of a cube of glass comprising a second volume diagonal face, said first volume diagonal face proximately contacting said second volume diagonal face.

8. The apparatus of claim 1, said first two-dimensional detector array comprising at least m-by-n pixels, where m and n are each positive integers of at least two.

9. The apparatus of claim 1, said additive manufacturing device further comprising:

a second temperature sensor, comprising;

a third two-dimensional detector array configured to image a second plane, the second plane intersecting the first plane at an angle greater than forty degrees, said third two-dimensional detector array configured to generate a third set of signals; and

a fourth two-dimensional array of detectors imaging the second plane, said fourth two-dimensional detector array configured to generate a fourth set of signals,

said controller configured to calculate at least a second temperature using said third set of signals and said fourth set of signals.

10. The apparatus of claim 9, said additive manufacturing device further comprising:

a first imaging optic coupled to said first temperature sensor; and

a second imaging optic coupled to said second temperature sensor, said first temperature sensor configured to monitor the object in a first location along the first plane, said second temperature sensor configured to monitor the object within two millimeters of the first location along the second plane.

11. A method for determining a temperature of an object under construction, comprising the steps of:

providing an additive manufacturing device comprising;

a working platform holding the object under construction; and

a temperature sensor, comprising;

a first two-dimensional detector array optically linked to a plane parallel to a surface of the working platform; and

a second two-dimensional detector array optically linked to the plane parallel to the working platform;

generating a first set of signals using said first two-dimensional detector array;

generating a second set of signals using said second two-dimensional detector array; and

using a controller to calculate a set of temperatures using said first set of signals and said second set of signals.

12. The method of claim 11, further comprising the steps of:

depositing a powder on the plane parallel to the surface of the working platform using a screed of said additive manufacturing device;

sintering the powder generating a melt pool of melted powder using a laser of said additive manufacturing device;

sensing the melt pool using said temperature sensor;

using the calculated set of temperatures in a step of at least one of;

controlling said laser; and

determining a quality of sintering of the object.

13. The method of claim 12, further comprising the step of:

said controller using said calculated set of temperatures in a feedback control loop to redirect said laser to further lase a previously lased position of the object.

14. The method of claim 13, further comprising the step of:

prior to said step of sensing, aligning said first two-dimensional detector array to image on a detector element by detector element level a same position of the object observed by said second two-dimensional detector, said set of temperatures corresponding to individual imaged locations of the object imaged by elements of the first two-dimensional detector.

15. The method of claim 11, further comprising the step of:

within a period of less than one second, monitoring at least two locations of the object at least three millimeters apart using said first two-dimensional detector array and said second two-dimensional detector array.

16. The method of claim 15, said at least two locations comprising:

a first location heated using a first laser, of said additive manufacturing device, at a first wavelength; and

a second location heated using a second laser, of said additive manufacturing device, at a second wavelength, said first wavelength and said second wavelength separated by at least forty nanometers.

17. The method of claim 11, further comprising the step of:

said controller using a-priori knowledge of shape of a spectrum of a blackbody radiator as related to the first set of signals and the second set of signals to determine the set of temperatures.

18. The method of claim 11, further comprising the step of:

using said temperature sensor to monitor, within one-tenth of a second, at least two sintering locations sintered by a corresponding at least two lasers of said additive manufacturing device.

19. The method of claim 11, further comprising the step of:

using each of said first-two dimensional detector array and said second two-dimensional detector array to simultaneously monitor a current sintering location of the object with a first set of pixels and at least one previously sintered location of the object with a second set of pixels to determine at least a cooling rate of a section of the object.

20. The method of claim 12, further comprising the step of:

recording data from both said first two-dimensional detector array and said second two-dimensional detector array; and

using said data to determine cooling parameter of the melt pool of the object after lasing with a laser of said additive manufacturing device.