Layer Transfusion with Part Heating for Additive Manufacturing

• US 20130078013A1
• Filed: 09/21/2012
• Published: 03/28/2013
• Est. Priority Date: 09/23/2011
• Status: Active Grant

• Current Assignee: Evolve Additive Solutions, Inc.
• Original Assignee: Stratasys Incorporated
• Inventors: Chillscyzn, Steven A., Comb, James W., Hanson, William J., Sanders, J. Randolph, Bacus, Michael W.
• Granted Patent: US 8,718,522 B2
• Time in Patent Office: Days
• US Class Current: 399/307
• CPC Class Codes: B29C 64/141 using only solid materials
• CPC Class Codes: B29C 64/147 using sheet material, e.g. laminated object manufacturing [LOM] or laminating sheet material precut to local cross sections of the 3D object
• CPC Class Codes: B29C 64/205 Means for applying layers
• CPC Class Codes: B29C 64/232 for motion along the axis orthogonal to the plane of a layer
• CPC Class Codes: B29C 64/236 for motion in a direction within the plane of a layer
• 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: G03G 15/1625 on a base other than paper
• CPC Class Codes: G03G 15/169 with means for preconditioning the toner image before the transfer G03G15/095 and G03G15/11 take precedence
• CPC Class Codes: G03G 15/2021 Plurality of separate fixing and/or cooling areas or units, two step fixing
• CPC Class Codes: G03G 15/224 Machines for forming tactile or three dimensional images by electrographic means, e.g. braille, 3d printing
• CPC Class Codes: G03G 15/24 whereby at least two steps are performed simultaneously
• CPC Class Codes: G03G 2215/1695 at the second or higher order transfer point
• CPC Class Codes: Y10T 156/17 Surface bonding means and/or assemblymeans with work feeding or handling means

Abstract

An additive manufacturing system comprising a transfer medium configured to receive the layers from a imaging engine, a heater configured to heat the layers on the transfer medium, and a layer transfusion assembly that includes a build platform, and is configured to transfuse the heated layers onto the build platform in a layer-by-layer manner to print a three-dimensional part.

Claims

1. An additive manufacturing system for printing a thermoplastic part, the additive manufacturing system comprising:

an imaging engine configured to develop imaged layers of a thermoplastic-based powder having a fusion temperature;

a movable build platform;

a transfer medium having a transfer surface configured to sequentially receive and convey the imaged layers from the imaging engine to the build platform, and having an opposing contact surface;

a heater configured to heat the imaged layers on the transfer medium to at least the fusion temperature;

a heater configured to heat a previously transfused layer of a thermoplastic part being printed on the build platform to at least the fusion temperature;

a heated layer transfusion element configured to transfuse a heated imaged layer conveyed by the transfer medium onto the heated previously fused layer by engaging the contact surface of the transfer medium so that the transfer medium and the heated imaged layer are pressed between the transfuse element and the build platform, and to disengage therefrom without releasing the transfer medium from the transfused layer; and

a cooling unit configured to actively cool the transfused layer to below the fusion temperature while it remains on the transfer medium, so as to transfix the transfused layer before delaminating it from the transfer medium.

2. The additive manufacturing system of claim 1, wherein the layer transfusion element is heated to the fusion temperature.

3. The additive manufacturing system of claim 1, wherein the layer transfusion element comprises a press plate.

4. The additive manufacturing system of claim 3, wherein the moveable build platform is configured to release the transfer medium from the transfused layer by moving away from the transfer medium.

5. The additive manufacturing system of claim 1, wherein the transfer medium comprises a rotatable belt, and wherein the rotatable belt revolves in a rotational path from the imagine engine, past the heater, in between the layer transfusion element and build platform, and past the cooling unit.

6. The additive manufacturing system of claim 1, wherein the layer transfusion element comprises a fusion roller.

7. The additive manufacturing system of claim 6, wherein the transfer medium comprises a rotatable belt that revolves in a rotational path from the imagine engine, past the heater, in between the layer transfusion element and build platform, and past the cooling unit, and wherein the moveable built platform is configured to move at a synchronized rate and direction with the rotatable belt while the fusion roller presses the heated layer to previously fused layers of the printed three-dimensional part.

8. The additive manufacturing system of claim 7, and further comprising a release roller disposed downstream of the cooling unit in the rotational path of the rotatable belt and configured to engage the contact surface of the rotatable belt so as to assist in delaminating the transfused layer from the transfer medium after it is transfixed.

9. The additive manufacturing system of claim 1, wherein the heater comprises a non-contact radiant heater.

10. An additive manufacturing system for printing a thermoplastic part, the additive manufacturing system comprising:

an imaging engine configured to develop imaged layers of a thermoplastic-based powder having a fusion temperature;

a movable build platform;

a transfer medium having a transfer surface configured to sequentially receive and convey the imaged layers from the imaging engine to the build platform, and having an opposing contact surface;

a heater configured to heat the imaged layers on the transfer medium to at least the fusion temperature;

a heater configured to heat a previously transfused layer of a thermoplastic part being printed on the build platform to at least the fusion temperature;

a heated fusion roller configured to be heated to a transfer temperature and further configured to transfuse a heated imaged layer conveyed by the transfer medium onto the heated previously fused layer by engaging and rolling across the contact surface of the transfer medium, and to disengage therefrom without releasing the transfer medium from the transfused layer;

a cooling unit configured to actively cool the transfused layer to below the fusion temperature while it remains on the transfer medium so as to transfix the transfused layer; and

a release roller disposed downstream of the cooling unit and configured to engage the contact surface of the transfer medium so as to assist in delaminating the transfused layer from the transfer medium.

11. The additive manufacturing system of claim 10, wherein the transfer medium is a rotatable belt that follows a rotational path from the imagine engine, past the heater configured to heat the imaged layers, in between the fusion roller and build platform, past the cooling unit and the release roller, and returning to the imaging engine.

12. The additive manufacturing system of claim 11, wherein the moveable built platform is configured to move at a synchronized rate and direction with the rotatable belt while the fusion roller is engaged to transfuse a heated imaged layer.

13. The additive manufacturing system of claim 10, wherein one or more heaters comprise a non-contact radiant heater.

14. The additive manufacturing system of claim 10, wherein the cooling unit comprises at least one air knife, at least one air jet, or a combination thereof.

15. A method for printing a three-dimensional part with an additive manufacturing system, the method comprising:

imaging a layer of the three-dimensional part from a thermoplastic-based powder;

transferring the imaged layer to a transfer medium;

heating the imaged layer while the imaged layer is retained on the transfer medium;

heating a top surface of the three-dimensional part;

transfusing the heated layer to the heated top surface of the three-dimensional part;

cooling the transfer medium and at least a portion of the transfused layer; and

releasing the transfused layer from the cooled transfer medium such that the transfused layer remains adhered to the three-dimensional part.

16. The method of claim 15, wherein imaging the layer comprises developing the layer with an electrophotography engine.

17. The method of claim 15, and further comprising further cooling the transfused layer to hold the printed three-dimensional part at about an average part temperature that is below a deformation temperature of the three-dimensional part.

18. The method of claim 15, wherein the transfer medium comprises a rotatable belt, and wherein the method further comprises:

rotating the rotatable belt at a rotational rate; and

moving the three-dimensional part at a rate that is synchronized with the rotational rate of the rotatable belt.

19. The method of claim 15, wherein heating the imaged layer comprises heating the imaged layer to at least a fusion temperature of the thermoplastic-based powder, and wherein heating the top surface of the three-dimensional part comprises heating the top surface of the three-dimensional part to at least the fusion temperature of the thermoplastic-based powder.

20. The method of claim 15, wherein the transfused layer defines a new top surface of the three-dimensional part, and wherein the method further comprises:

imaging a subsequent layer of the three-dimensional part from the thermoplastic-based powder;

transferring the subsequent imaged layer to the transfer medium;

heating the subsequent imaged layer while the subsequent imaged layer is retained on the transfer medium;

heating the new top surface of the three-dimensional part; and

transfusing the heated subsequent layer to the heated new top surface of the three-dimensional part.