Apparatus and method for forming three-dimensional objects using linear solidification

• US 9,075,409 B2
• Filed: 02/22/2013
• Issued: 07/07/2015
• Est. Priority Date: 06/28/2011
• Status: Active Grant

• Current Assignee: Gulf Filtration Systems Inc. (Desktop Metal, Inc.)
• Original Assignee: Gulf Filtration Systems Inc. (Desktop Metal, Inc.)
• Inventors: El-Siblani, Ali, Shkolnik, Alexandr
• Primary Examiner(s): HINDENLANG, ALISON L
• Application Number:
  US13/774,355
• Publication Number:
  US 20140052288A1
• Time in Patent Office: 865 Days
• US Class Current: 1/1
• CPC Class Codes: B29C 64/124 using layers of liquid which are selectively solidified
• CPC Class Codes: B29C 64/135 the energy source being concentrated, e.g. scanning lasers or focused light sources
• CPC Class Codes: B29C 64/214 Doctor blades
• CPC Class Codes: B29C 64/264 Arrangements for irradiation
• CPC Class Codes: B29K 2105/24 crosslinked or vulcanised
• 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: G05B 19/042 using digital processors G05B19/05 takes precedence

Abstract

An apparatus and method for making a three-dimensional object from a solidifiable material using a linear solidification device is shown and described. In certain examples, the linear solidification device includes a laser diode that projects light onto a scanning device, such as a rotating polygonal mirror or a linear scanning micromirror, which then deflects the light onto a photohardenable resin. As a result, the linear solidification device scans a line of solidification energy in a direction that is substantially orthogonal to the direction of travel of the laser diode. In other examples, the linear solidification device is a laser device array or light emitting diode array that extends in a direction substantially orthogonal to the direction of travel of the array.

Claims

1. A method of making a three-dimensional object from a photohardenable resin, comprising:

providing original solidification energy source event data corresponding to a cross-section of the three-dimensional object, wherein the original solidification energy source event data comprises a plurality of original solidification energy source event data items, and each original solidification energy source event data item is associated with a position along a build envelope scanning axis and is indicative of a change in the energization state of a selectively, activatable and deactivatable laser diode;

calculating modified solidification energy source event data corresponding to the cross-section of the three-dimensional object, wherein the modified solidification energy source event data comprises a plurality of modified solidification energy source event data items, each modified solidification energy source event data item corresponds to one of the respective original solidification energy source event data items and is based on the associated position along the build envelope scanning axis of its corresponding original solidification energy source event data item;

solidifying the solidifiable material in accordance with the modified solidification energy source event data to form the cross-section of the three-dimensional object, comprising;

moving a linear solidification device including the selectively activatable and deactivatable laser diode and a linear scanning device along a first axis, and

progressively exposing the photohardenable resin to solidification energy along the build envelope scanning axis as the linear solidification device moves along the first axis by selectively activating and deactivating the laser diode based on the modified solidification energy source event data, wherein the linear scanning device scans solidification energy received from the laser diode onto the photohardenable resin.

2. The method of claim 1, wherein linear scanning device comprises a rotating energy deflector, and the step of progressively exposing the solidifiable material to solidification energy along the build envelope scanning axis comprises rotating the rotating energy deflector and selectively activating the laser diode based on the modified solidification energy source event data such that the rotating energy deflector deflects solidification energy received from the solidification energy source to the solidifiable material.

3. The method of claim 2, wherein the rotating energy deflector is a mirror having one or more facets, and each facet has a rotational position at which it is in optical communication with the laser diode.

4. The method of claim 1, wherein each original solidification energy source event data item is a position along the build envelope scanning axis relative to a scanning axis border, and the step of calculating modified solidification energy source event data corresponding to the cross-section of the three-dimensional object comprises calculating CPU ticks based on the associated position along the build envelope scanning axis of each original solidification energy source event data item in accordance with the following formula:

5. The method of claim 4, further comprising:

providing test part object data corresponding to a plurality of test parts and comprising a plurality of test part data items, each test part data item including starting data indicative of a time at which a solidification source is activated, and ending data indicative of a time when the solidification source is deactivated, each test part data item corresponding to a same test part length;

solidifying a solidifiable material to create the plurality of test parts based on the test part data items;

measuring the length of each test part; and

determining at least one of the constants c₀, c₁, c₂, and c₃ based on the difference between the measured length and the test part length corresponding to the test part data item for each test part.

6. The method of claim 5, wherein the step of determining at least one of the constants c₀, c₁, c₂, and c₃ comprises solving the following set of equations:

7. The method of claim 1, further comprising providing test part object data corresponding to a plurality of test parts spaced apart in a direction along the build envelope, each test part having a length along the build envelope scanning axis, solidifying a test part solidifiable material in accordance with the test part object data to create the plurality of test parts, and measuring the length of each test part.

8. The method of claim 7, wherein each test part is a rectangular block, and the test part object data for each test part corresponds to an equal test part length along the build envelope scanning axis and an equal test part width.

9. The method of claim 7, wherein the test part object data for each test part corresponds to build envelope scanning axis locations, and the build envelope scanning axis locations for each test part are offset from the build envelope scanning axis locations of an adjacent test part.

10. The method of claim 1, wherein the original solidification energy source event data comprises a plurality of Old CPU tick values, and the step of calculating modified solidification energy source event data corresponding to the cross-section of the three-dimensional object comprises calculating New CPU tick values in accordance with the following formula:

(New CPU ticks)_i=(Old CPU ticks)_i+(Δ

CPU ticks)*C

wherein,

New CPU ticks=modified CPU tick data item value corresponding to original solidification source event data item i

Old CPU ticks=Original solidification source event data item indicative of activation or deactivation of solidification energy source;

Δ

CPU ticks=time, in CPU ticks, for solidification energy to scan from the build envelope scanning axis location corresponding to Old CPU ticks and the center point of the solidification energy source; and

C=dimensionless constant.

11. The method of claim 1, wherein the original solidification energy source event data comprises a plurality of original distances along the build envelope scanning axis, and the step of calculating modified solidification energy source event data corresponding to the cross-section of the three-dimensional object comprises calculating new distances along the build envelope scanning axis in accordance with the following formula:

y_{new i}=y_{old i}+(y_{center point}−

y_old)*C

wherein,

y_{new i}=modified distance of a solidification energy source event along the build envelope scanning axis (mm) relative to a scanning axis border location;

y_{old i}=original distance of a solidification source event along the build envelope scanning axis relative to a scanning axis border location;

y_{center point}=distance (mm) from the center point of the solidification energy source and the reference location along the build envelope scanning axis; and

C=dimensionless constant.

12. A method of making a three-dimensional object from a photohardenable resin, comprising:

providing object data representative of a cross-section of the three-dimensional object;

providing a linear solidification device comprising a selectively activatable and deactivatable laser diode in optical communication with a linear scanning device, wherein the linear solidification device moves in a first direction and progressively solidifies the photohardenable resin in a second direction as the selectively activatable and deactivatable laser diode transmits solidification energy to the linear scanning device which deflects the solidification energy onto the surface of the photohardenable resin at a scanning speed that varies with a position of solidification energy along the second direction as the linear solidification device moves in the first direction,

modifying the object data to compensate for the variation of the scanning speed in the second direction; and

solidifying the photohardenable resin by selectively activating and deactivating the laser diode based on the modified object data.

13. The method of claim 12, wherein the linear scanning device comprises a rotating energy deflector, when the laser diode transmits solidification energy to the rotating energy deflector, the rotating energy deflector deflects the solidification energy onto the surface of the solidifiable material such that the solidification energy progressively solidifies the solidifiable material in the second direction.

14. The method of claim 12, wherein the object data comprises a plurality of object data items, each object data item being indicative of a solidification energy source event and corresponding to a position along the second direction, and the step of modifying the object data comprises modifying the position along the second direction at which the solidification source event occurs for the corresponding object data item.

15. The method of claim 12, wherein each of the object data items is a number of CPU ticks indicative of a time at which the laser diode is activated or deactivated.

16. The method of claim 12, further comprising:

providing test part object data corresponding to a plurality of test parts spaced apart along the second direction and comprising a plurality of sets of test part data items, each set of test part data items including starting data indicative of a time at which a solidification source is activated, and ending data indicative of a time when the solidification source is deactivated, each set of test part data items corresponding to a same test part length;

solidifying a solidifiable material to create the plurality of test parts; and

measuring the length of each test part, wherein the step of modifying the object data to compensate for the variation of the scanning speed in the second direction comprises modifying the object data based on the measured length of each test part.

17. The method of claim 16, wherein each test part is a rectangular block, and the test part object data for each test part corresponds to an equal test part length along the second direction and an equal test part width along the first direction.

18. The method of claim 17, wherein each set of test part object data items for each test part corresponds to first and second locations along the second direction, and the first and second locations along the second direction for each test part are offset along the second direction from the first and second locations for an adjacent test part.

19. The method of claim 12, wherein the step of modifying the object data to compensate for the variation of the scanning speed in the second direction further comprises modifying the object data to compensate for a variation in solidification energy density in the second direction.

20. An apparatus for making a three-dimensional object from a photohardenable resin, comprising:

a linear solidification device comprising a selectively activatable and deactivatable laser diode in optical communication with a linear scanning device, wherein the linear solidification device is movable in a first direction and is configured so that when the selectively activatable and deactivatable laser diode transmits solidification energy to the linear scanning device, the linear scanning device deflects the solidification energy onto the surface of the photohardenable resin to progressively solidify the photohardenable resin in a second direction while the linear solidification device moves in the first direction based on modified object data;

a controller operatively connected to the linear solidification device and configured to control the movement of the linear solidification device in the first direction and the progressive solidification of the photohardenable resin in the second direction by selectively activating and deactivating the laser diode based on the modified object data;

a computer readable medium having computer executable instructions programmed thereon to calculate the modified object data based on original object data, the instructions performing the following steps;

receiving the original object data, wherein the original object data comprises a plurality of original object data items, each data item being indicative of a solidification energy source event and being associated with a location along the second direction;

calculating modified object data items corresponding to each original object data item, wherein the modified object data item is calculated based on the corresponding original object data and the location along the second direction with which the corresponding original object data item is associated.

21. The apparatus of claim 20, wherein the linear scanning device comprises a rotating energy deflector.

22. The apparatus of claim 21, wherein the rotating energy deflector is a mirror having one or more facets, and each facet has a rotational position at which it is in optical communication with the laser diode.

23. The apparatus of claim 21, further comprising at least one lens between the rotating energy deflector and a source of the photohardenable resin, wherein the lens is coated with an anti-reflective coating such that the coated lens transmits at least 95% of incident light having a wavelength ranging from about 380 nm to about 420 nm.

24. The apparatus of claim 20, wherein the original object data comprises a plurality of original object data items, and each of the original object data items is a number of CPU ticks at which a solidification energy source event occurs.

25. The apparatus of claim 20, wherein the original object data items each comprise a position along the second direction at which a solidification energy source event occurs, and the step of calculating modified object data items corresponding to each original object data item comprises calculating a number of CPU ticks based on the following formula:

26. The apparatus of claim 20, further comprising an vacuum blade having a length extending along the second direction and which is operatively connected to the linear solidification device such that when the linear solidification device moves in the first direction, the vacuum blade moves in the first direction.

27. The apparatus of claim 26, wherein the vacuum blade comprises first and second surfaces spaced apart along the first direction which define an interior space between the first and second surfaces, and a vacuum pump in fluid communication with the interior space and operable to maintain the interior space below atmospheric pressure.

28. The apparatus of claim 27, wherein the vacuum blade further comprises first and second projecting edges, the first projecting edge is connected to the first surface and projects away from the first surface and the second surface, and the second projecting edge is connected to the second surface and projects away from the second surface and the first surface, and the first and second projecting edges are spaced apart from one another along the first direction.

29. The apparatus of claim 26, wherein the linear solidification device and the vacuum blade are spaced apart along a third direction.

30. The apparatus of claim 26, wherein when the linear solidification device traverses a plurality of first direction locations and progressively solidifies the photohardenable resin in the second direction, the vacuum blade traverses each first direction location before the linear solidification device progressively solidifies the photohardenable resin at the each first direction location.