3-D PRINTING METHOD HAVING INCREASED STRENGTH OF THE PRODUCED OBJECT

Abstract

The invention relates to a method (100) for producing a three-dimensional object (10), having the following steps: a printing structure (11), which defines an interior (12), is produced (110) from a printing material (21) by means of 3-D printing; a filling material (22), which comprises at least one liquid or pasty monomer (23), is introduced (120) into the interior (12); the monomer (23) is polymerized (130) to form a polymer (24). The invention further relates to a 3-D printer (30) for performing the method (100), wherein a first printing head (31) for the printing material (21) and a second printing head (32) for the filling material (22) are provided, wherein the outlet opening (32a) of the second printing head (32) for the filling material (22) has a cross-sectional area that is greater than that of the outlet opening (31a) of the first printing head (31) for the printing material (21) by a factor of at least 2, preferably by a factor of at least 5, and/or a base plate (33) is provided, on which the printing structure (11) should be constructed, wherein the base plate (33) has a feed-through (34) for the filling material (22), which feed-through can be connected, on the side facing away from the printing structure (11), to a pressurized source (26) for the filling material (22).

Claims

1. A method (100) for producing a three-dimensional object (10), the method comprising the following steps: manufacturing (110) the printed structure (11), which defines an internal space (12), by 3D printing from a printing material (21); introducing (120) a filling material (22), which comprises at least one liquid or paste-like monomer (23), into the internal space (12); and polymerizing (130) the monomer (23) to form a polymer (24).

2. The method (100) as claimed in claim 1, characterized in that the internal space (12) defines a negatives shape of an object structure (28) to be produced from the polymer (24), or a part of the object structure (28).

3. The method (100) as claimed in claim 1, characterized in that the filling material contains at least one solid filler (25).

4. The method (100) as claimed in claim 3, characterized in that the solid filler is a reinforcing substance.

5. The method (100) as claimed in claim 1, characterized in that the printing material (21) is composed (110) with a first 3D printing head (31) to form the printed structure (11), and in that the filling material (22) is introduced (120) into the internal space (12) with a second 3D printing head (32).

6. The method (100) as claimed in claim 5, characterized in that an outlet opening (32a) of the second printing head (32) for the filling material (22) has a cross-sectional area which is greater by a factor of at least 2 than an outlet opening (31a) of the first printing head (31) for the printing material (21).

7. The method (100) as claimed in claim 1, characterized in that the printing material is a water-soluble material (21).

8. The method (100) as claimed in claim 1, characterized in that the printed structure (11) is removed (140) from the object (10) after the polymerization (130) of the monomer (23).

9. The method (100) as claimed in claim 1, characterized in that the filling material (22) is brought (125) into engagement with indentations (13) of the printed structure (11), so that a form-fit connection with the indentations (13) is formed after the polymerization (130) of the monomer (23).

10. The method (100) as claimed in claim 1, characterized in that the monomer (23) polymerizes to form a polymer (24) that is materially the same as the printing material (21).

11. The method (100) as claimed in claim 1, characterized in that further printing material (21) is applied (110) by 3D printing after the introduction (120) of the filling material (22).

12. The method (100) as claimed in claim 1, characterized in that the internal space (12) is connected (135) during the polymerization (130) of the monomer (23) to a pressurized source (26) of the filling material (22).

13. The method (100) as claimed in claim 1, characterized in that the printed structure (11) is constructed (110) with the aid of a carrier structure (14) which does not belong to the object (10) and can be separated from the object (10).

14. The method (100) as claimed in claim 1, characterized in that the internal space (12) encloses an insert (15) to be embedded in the object (10).

15. The method (100) as claimed in claim 1, characterized in that caprolactam is selected as the monomer (23) and is polymerized (130) to form the polyamide PA6 as a polymer (24), and/or propene is selected as the monomer (23) and is polymerized to form PBT as a polymer, and/or cyclic PBT or CBT is selected as the monomer (23) and is polymerized to form PBT as a polymer, and/or laurolactam is selected as the monomer (23) and is polymerized (130) to form the polyamide PA12 as a polymer (24).

16. A 3D printer (30) for carrying out a method (100) according to claim 1, characterized in that a first printing head (31) for the printing material (11) and a second printing head (32) for the filling material (22) are provided, the outlet opening (32a) of the second printing head (32) for the filling material (22) having a cross-sectional area which is greater by a factor of at least 2, preferably by a factor of at least 5, than the outlet opening (31a) of the first printing head (31) for the printing material (21), and/or a base plate (33) is provided, on which the printed structure (11) is to be constructed, the base plate (33) having a feed-through (34) for the filling material (22), which feed-through can be connected on the side facing away from the printed structure (11) to a pressurized source (26) of the filling material (22).

17. The method (100) as claimed in claim 3, characterized in that the solid filler is a reinforcing substance in the form of fibers.

18. The method (100) as claimed in claim 5, characterized in that an outlet opening (32a) of the second printing head (32) for the filling material (22) has a cross-sectional area which is greater by a factor of at least 5 than an outlet opening (31a) of the first printing head (31) for the printing material (21).

19. The method (100) as claimed in claim 1, characterized in that the printing material is a water-soluble gelatin.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] FIG. 1 shows a flowchart of the method 100 according to the invention;

[0038] FIGS. 2a through 2f show an exemplary embodiment of the method 100 according to the invention;

[0039] FIG. 3 shows a variant of the method 100, carried out with a different 3D printer 30;

[0040] FIG. 4 shows an example of an indentation 13 and insert 15 in the internal space

DETAILED DESCRIPTION

[0041] According to FIG. 1, in step 110 a printed structure 11 is first manufactured. This printed structure 11 contains an internal space 12, which is filled in step 120 with a filling material 22 that contains reinforcing fibers 25. In this case, the filling material 22 is optionally brought into engagement with indentations 13 in the printed structure. Optionally, further iterations may then take place, in which the printed structure 11 is extended and filling material 22 is introduced into corresponding internal spaces 12.

[0042] In step 130, the monomer 23 contained in the filling material 22 is polymerized to form a polymer 24, further filling material 22 optionally being supplied (step 135) during the polymerization.

[0043] Subsequently, according to the user's choice, the composite consisting of the printed structure 11 and polymer 25, reinforced with fibers 25, contained in the internal space 12 thereof, may be used as a finished object can, or the printed structure 11 may be removed in step 140.

[0044] FIG. 2 illustrates by way of example the way in which an exemplary embodiment of the method 100 is carried out with an exemplary 3D printer 30.

[0045] According to FIG. 2a, the 3D printer 30 comprises a base plate 33, on which the printed structure 11 is to be constructed. The base plate 33 is arranged in a heatable construction space, which in this exemplary embodiment is at a temperature of 160 C. Furthermore, three printing heads 31, 32 and 36 are provided. The first printing head 31 heats a printing material 21 which is in the form of granules, and delivers it in plasticized form through a nozzle having an outlet opening 31a selectively at the positions which belong to the printed structure 11. The second printing head 32 receives both a monomer 23 and reinforcing fibers 25. Inside the second printing head 32, the monomer 23 and the reinforcing fibers 25 are mixed before the filling material 22, which emerges from the outlet opening 32a. The third printing head 36 heats a further material 27, which is in the form of granules, to plasticization and delivers it through its outlet opening 36a the third printing head 36 is used to apply a carrier structure 14 on the base plate 33. In each layer constructed, the material 27 of the carrier structure 14 is applied at the positions belonging to the carrier structure 14, and the printing material 21 is applied at the positions belonging to the printed structure 11.

[0046] FIG. 2b shows a snapshot at a later instant. Both the carrier structure 14 and the printed structure 11 is grown in height, with two limbs 11a and 11b of the printed structure 11 engaging in recesses 14a and 14b, corresponding thereto, of the carrier structure 14. The function of the carrier structure 14 is in this case to keep the printed structure 11 horizontal, even though the limbs 11a and 11b of different length. In the state shown in FIG. 2b, the production of the carrier structure 14 is completed; the associated third printing head 36 is therefore no longer indicated. The printed structure 11 defines an internal space 12, which is configured as a trough and is bounded by four walls 12a, 12b, 12c and 12d. The limbs 11a and 11b are also internally hollow and fillable with filling material 22, although this, be seen in the perspective selected and is therefore also not indicated.

[0047] FIG. 2c shows a snapshot at a later instant. The trough-shaped internal space 12, as well as the cavities connecting their width in the limbs 11a and 11b, are filled with the filling material 22. The filling material 22 is in this case sufficiently fluid that it can also be cast into these cavities. In other configurations, it may for example also be laid in tracks with a consistency of soft wax.

[0048] FIG. 2d shows a snapshot at a later instant. The trough-shaped internal space 12, filled with filling material 22, of the printed structure 11 has been closed with a cover 11e, which is made printing material 21 and in which a circular groove 11f is been left open. Radially on both sides of this groove 11f, two concentric cylindrical walls 11c and 11d have subsequently been constructed with the first printing head 31. Between these two cylindrical walls 11c and 11d, there is a cavity 11e which is fluidically connected to the trough-shaped internal space 12 and therefor, like the cavities in the limbs 11a and 11b, is functionally to be assigned to this internal space 12. In the state shown in FIG. 2d, the second printing head is in the process of filling the cavity 12e with further filling material 22. The sooner this is completed, the monomer 23 contained in all of the filling material 22 is polymerized to form the polymer 24. This takes place automatically because of the temperature prevailing in the construction space. At this temperature, the monomer 23 as an established processing time, after which the polymerization begins.

[0049] In an alternative configuration, the filling material 22 may also be introduced alternately by two printing heads 32, 32, which contain two components 22a, 22b of the filling material 22. For example, the printing head 32 may contain a mixture 22a of monomer 23, catalyst and reinforcing fibers 25, and the printing head 32 may contain a mixture 22b of Moderator and monomer 23, activator and reinforcing fibers 25. By the alternate application, thorough mixing then takes place inside the internal space 12. In the mixture activated in this way, the polymerization may be initiated by temporary eating to about 130 C. and subsequently continued at a construction space temperature of between 40 C. and 70 C.

[0050] Furthermore, the filling material 22 may also be present in a wax-like consistency such that it can itself function as a support structure for the cover 11e.

[0051] In order to keep the result of the polymerization isotropic and homogeneous, polymerization may also be carried out in a high vacuum. In this way, various structural configurations are possible, which may be used deliberately in order to modify the component properties.

[0052] FIG. 2e shows the finished object 10 obtain in a perspective representation. After the polymerization, the cavity (internal space part) 12e has been closed with a cover 11g using printing material 21 from the first printing head 31. Subsequently, the object 10, including the carrier structure 14, has been removed from the 3D printer 30 and the carrier structure 14 has been dissolved.

[0053] FIG. 2f shows the finished object can in a sectional drawing. Wherever there was filling material 11 during construction, there is now polymer 24, which is reinforced with fibers 25. This fiber-reinforced polymer 24 forms an object structure 28, which represents an isotropic core of the object.

[0054] FIG. 3 shows a snapshot of a variant of the process in FIG. 2, in which a different 3D printer 30 specially designed for carrying the method to the invention is used, in partially cutaway section. This 3D printer 30 has, in its base plate 33, a feed-through 34 which can be connected, on a side facing away from the printed structure 11 and the poor as we from the object and as a whole, to a pressurized source 26 of the filling material 22. In the carrier structure 14, as well as in the left-hand limb 11a of the printed structure 11, a passage 11h has been left, through which the filling material 22 can flow into the internal space 12. This partially cutaway view illustrates that ultimately a common internal space 12 extends through the entire printed structure 11, from the limbs 11a and 11b as far as the concentric cylindrical walls 11c and 11d. In contrast to FIG. 2, the printed structure 11 is in this case been manufactured not in stages, which have been interrupted by the application of filling material 22, but in one working step, including the final cover layer 11g. The overhangs may, for example, be produced by corresponding adaptation of the carrier structure 14 which is no longer visible in the state shown in FIG. 3.

[0055] It is possible to incorporate mixed structures made of the material 27 of the carrier structure 14 for producing the mixture 22. These may then be jointly removed when removing the carrier structure 14. This allows simpler handling during the polymerization.

[0056] FIG. 4 shows, by way of example, the way in which the connection between the printed structure 11 and an object structure 28, resulting from the filling material 22 after the polymerization, may be reinforced by an indentation 13 of the printed structure 11 in the internal space 12. When the monomer 23 contained in the filling material 22 is polymerized to form the polymer 24, the polymer 24 which is in engagement with the indentation 13 is connected there with a form-fit to the printed structure 11.

[0057] Furthermore, FIG. 4 shows the way in which an insert 15 may be cast in the internal space 12 with the filling material 22. In this example, the insert 15 is an electronic printed circuit board having plug-in contacts 15a, to which the printed structure 11 leaves an access open. The printed circuit board 15 is heat-sensitive, and the printing material 21 of which the printed structure 11 consists therefore cannot be cast directly around it, since this printing material 21 does not become liquid until temperatures of 160 C. By casting the filling material 22 and the subsequent polymerization the electronic printed circuit board 15 is not excessively exposed to heat.