SINTERING USING THERMAL IMAGE FEEDBACK

• US 20040200816A1
• Filed: 04/09/2003
• Published: 10/14/2004
• Est. Priority Date: 04/09/2003
• Status: Active Grant

• Current Assignee: 3D Systems, Inc. (3D Systems Corporation)
• Original Assignee: 3D Systems, Inc. (3D Systems Corporation)
• Inventors: Allanic, Andre-Luc, Chung, Mark
• Granted Patent: US 6,815,636 B2
• Time in Patent Office: Days
• US Class Current: 219/121.83
• CPC Class Codes: B29C 35/0288 Controlling heating or curing of polymers during moulding, e.g. by measuring temperatures or properties of the polymer and regulating the process controlling or regulating chemical, physical or physico- chemical processes in general B01J19/0006
• CPC Class Codes: B29C 64/153 using layers of powder being selectively joined, e.g. by selective laser sintering or melting
• 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: G05D 23/1919 characterised by the type of controller
• CPC Class Codes: G05D 23/27 with sensing element responsive to radiation

Abstract

A method and apparatus for forming three dimensional objects by laser sintering that utilizes a broad area thermal vision system such as an infrared camera that can measure multiple temperatures across the target area and use that temperature data as feed back to a control system that both adjusts a zoned radiant heater system and adjusts scan speed and laser power to control temperatures across the target area.

Claims

1. A method for forming a three dimensional article by laser sintering comprising the steps of:

(a) dispensing a first top layer of powder on a target area;

(b) moderating the temperature of said first top layer of powder to a predetermined temperature;

(c) directing an energy beam over said target area causing said first top layer of powder to fuse powder in select locations to form an integral layer;

(d) dispensing a second top layer of powder over the fused and unfused powder of said first top layer;

(e) moderating the temperature of said second top layer of powder to a second predetermined temperature;

(f) directing said energy beam over said target area causing said second top layer of powder to form a second integral layer bonded to said first integral layer; and

(g) repeating steps (a) to (f) to form additional layers that are integrally bonded to adjacent layers so as to form a three dimensional article, wherein the temperature moderating steps comprise;

using a machine vision system to image multiple temperatures of the current top layer of powder and adjusting those temperatures by adjusting the radiant heat output from a zoned radiant heater located above the target area.

2. The method of claim 1 wherein said machine vision system is an infrared camera.

3. The method of claim 2 wherein said energy beam is a carbon dioxide laser.

4. A method for forming a three dimensional article by laser sintering comprising the steps of:

(a) dispensing a first top layer of powder on a target area;

(b) moderating the temperature of said first top layer of powder to a predetermined temperature;

(c) directing an energy beam over said target area causing said first top layer of powder to fuse powder in select locations to form an integral layer;

(d) dispensing a second top layer of powder over the fused and unfused powder of said first top layer;

(c) moderating the temperature of said second top layer of powder to a second predetermined temperature;

(f) directing said energy beam over said target area causing said second layer of powder to form a second integral layer bonded to said first integral layer; and

(g) repeating steps (a) to (f) to form additional layers that are integrally bonded to adjacent layers so as to form a three dimensional article, wherein the directing steps include the sub steps of;

i. estimating, from known mathematical models, the desired temperatures in the region of the part being produced;

ii. reading, from the digital output of a machine vision system, the actual temperatures in the region of the part being produced; and

iii. adjusting the energy beam power and scan speed during the directing step based on differences between the desired and actual temperatures to achieve desired temperatures across said target area.

5. The method of claim 4 wherein said machine vision system is an infrared camera.

6. The method of claim 5 wherein said energy beam is a carbon dioxide laser.

7. An apparatus for producing parts from a powder, the apparatus comprising:

(a) a chamber having a target area at which an additive process is performed;

(b) means for depositing and leveling a layer of powder on said target area;

(c) means for fusing selected portions of a layer of the powder at said target area;

(d) machine vision system for measuring temperatures across the x-y coordinates of said target area; and

(e) radiant heater for heating said target area to control temperatures of fused and unfused powder at top surface of said target area.

8. The apparatus of claim 7 wherein said machine vision system is an infrared camera.

9. The apparatus of claim 8 wherein said radiant heater is a zoned radiant heater that has different zones to deliver different levels of energy to different parts of said target area.

10. The apparatus of claim 9 wherein the power output of said zoned radiant heater can be varied around the circumference of said zoned radiant heater.

11. The apparatus of claim 10 wherein the power output of said zoned radiant heater can be varied in a radial direction from the center of said target area.

12. An apparatus for producing parts from a powder, the apparatus comprising:

(a) a chamber having a target area at which an additive process is performed;

(b) means for depositing and leveling a layer of powder on the target area;

(c) an energy beam for fusing selected portions of a layer of the powder at the target area;

(d) machine vision system for measuring temperatures across the x-y coordinates of said target area; and

(e) control means for adjusting said energy beam scan speed and power in response to said measured temperatures and to desired temperatures estimated from mathematical models.

13. The apparatus of claim 12 wherein said machine vision system is an infrared camera.