Method and apparatus for 3d printing by selective sintering

Patent metadata

Field	Value
Publication number	US-2017173696-A1
Application number	US-201515304873-A
Country	US
Kind code	A1
Filing date	May 7, 2015
Priority date	May 8, 2014
Publication date	Jun 22, 2017
Grant date	—

Abstract

A system ( 100 ) for building a three dimensional object includes a powder delivery station ( 10 ) for applying a layer of powder material on a building tray ( 200 ), a digital printing station ( 30 ) for printing a mask pattern on the layer, a sintering station ( 50 ) for selectively sintering the portion of the layer that is defined by the mask to be sintered and a stage ( 250 ) for repeatedly advancing the building tray ( 200 ) to each of the powder delivery station, digital printing station and sintering station to build a plurality of layers that together form the three dimensional object. The mask pattern defines a negative portion of the layer to be sintered. Optionally, the system includes a die compaction station ( 40 ) for compacting per layer of powder material.

First claim

1 . A system for building a three dimensional object comprising:
a powder delivery station for applying a layer of powder material on a building tray; a digital printing station for printing a mask pattern on the layer, wherein the mask pattern defines a negative of a portion of the layer to be sintered; a sintering station for selectively sintering the portion of the layer that is defined by the mask to be sintered, wherein the sintering station includes a high thermal mass roller for sintering the layer; and a stage for repeatedly advancing the building tray to each of the powder delivery station, digital printing station and sintering station to build a plurality of layers that together form the three dimensional object.

2 . The system according to claim 1 , comprising a die compacting station for compacting the layer of powder material, wherein the compacting station includes a die for receiving the layer.

3 . The system according to claim 2 , wherein the die compacting station includes a heating element for warming a surface of the die that interfaces with the layer.

4 . The system according to claim 2 , wherein the die compacting station is operable to apply up to 100 MPa of pressure on the layer and wherein the die compacting station includes a lifting system for lifting the building tray toward the die.

5 . (canceled)

6 . The system according to claim 2 , wherein the die compacting station includes an anti-peeling mechanism, the anti-peeling mechanism including a foil positioned between the building tray and the die, wherein the foil is supported by two opposite edges to allow bowing of the foil during separation between the building tray and the die.

7 . The system according to claim 2 , comprising a controller for adjusting height of the building tray in a subsequent layer responsive to a thickness of the layer after compaction.

8 . The system according to claim 1 , comprising a cooling station for cooling the layer after sintering, wherein the cooling station includes air knives for providing jet stream of gas.

9 . (canceled)

10 . The system according to claim 1 , wherein the digital printing station is operable to dispense ink including a frit suspended in a liquid carrier, wherein the frit is formed from particles having a diameter of between 500 nm to 1 μm.

11 - 12 . (canceled)

13 . The system according to claim 1 , wherein the high thermal mass roller is heated to 0°-80° C. above the melting temperature of the powder.

14 . The system according to claim 1 , wherein the high thermal mass roller applies a pressure in the order of magnitude of 20-180 N/cm of roller length.

15 . The system according to claim 1 , wherein the sintering station includes an anti-peeling mechanism, the anti-peeling mechanism including a foil positioned between the high thermal mass roller and the layer.

16 . The system according to claim 1 , wherein the sintering station includes an array of vertical-cavity surface-emitting lasers (VCSEL) that swept over the layer for pre-heating.

17 . The system according to claim 1 , wherein the building tray includes at least one channel running substantially parallel to a surface of the tray on which the layer is positioned, through which fluid is introduced for cooling the building tray.

18 . (canceled)

19 . The system according to claim 1 , wherein the powder is aluminum and/or aluminum alloy powder.

20 . A method for building a three dimensional object comprising:
spreading a layer of powder on a building tray; printing a mask pattern on the layer, wherein the mask pattern defines a negative of a portion of the layer to be sintered, the mask pattern for the layer is defined by mask pattern data defining a shape of the three dimensional object; sintering the portion of the layer that is defined by the mask to be sintered, wherein the sintering is performed by a high thermal mass roller rolling over the layer; and repeating the spreading printing and sintering until the three dimensional object is completed.

21 . The method according to claim 20 , wherein the mask pattern is printed with a digital printer that dispenses ink and wherein the ink is configured to provide an insulating coating on a masked portion of the layer.

22 . (canceled)

23 . The method according to claim 21 , wherein the ink includes a liquid carrier selected to have an evaporation temperature that is lower than a melting temperature of the powder.

24 . The method according to claim 20 , comprising performing die compaction on the layer prior to the sintering and after the printing of the layer, wherein the pressure applied on the layer during the die compaction is up to 100 MPa.

25 . The method according to claim 24 , comprising performing warm die compaction, wherein the pressure applied on the layer during warm die compaction is up to 100 MPa, and wherein the warm die compaction is performed per layer after the printing of the layer.

26 - 27 . (canceled)

28 . The method according to claim 24 , comprising cooling the building tray during the die compaction.

29 - 30 . (canceled)

31 . The method according to claim 20 , wherein the high thermal mass roller is heated to 0°-30° C. above a melting temperature of the powder during the sintering.

32 . The method according to claim 20 , wherein the high thermal mass roller is pressed against the layer with a pressure in the order of magnitude of 10 N/cm of roller length.

33 . The method according to claim 20 , comprising cooling the building tray during sintering.

34 . The method according to claim 20 , comprising cooling the layer immediately after the sintering, wherein the cooling is performed with a jet stream of gas.

35 . The method according to claim 20 , comprising adjusting height of the building tray responsive to a thickness of one or more previous layers of the object being built.

36 - 38 . (canceled)

Assignees

• Stratasys Ltd

Inventors

• Sheinman Yehoshua

Classifications

• B22F12/63

  Rollers · CPC title

• B22F10/28 Primary

  Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM] · CPC title

• B22F12/20

  Cooling means · CPC title

• B22F12/13

  to preheat the material · CPC title

• B22F12/41

  characterised by the type, e.g. laser or electron beam · CPC title