PRINT HEAD FOR 3D PRINTER WITH AGILE PRESSURE EXERTION ON THE RAW MATERIAL

Abstract

The invention relates to a print head (10) for a 3D printer (1), comprising a feed (11) for a raw material (20) having variable viscosity and a nozzle (14) which tapers in the flow direction of a liquid phase (22) of the raw material (20) in order to output said liquid phase (22) through an outlet opening (15), wherein at least one pressure generator (12) is provided in order to raise the pressure of at least part of the liquid phase (22) to a base pressure, and wherein at least one pressure modulator (13) connected between the pressure generator (12) and the nozzle (14) is provided in order to modulate the pressure of at least part of the liquid phase (22) about the base pressure.

Claims

1. A print head (10) for a 3D printer (1), with a feeder (11) for a raw material (20) of variable viscosity and with a nozzle (14), tapering in a direction of flow of a liquid phase (22) of the raw material (20), for dispensing the liquid phase (22) through a discharge opening (15), wherein at least one pressure generator (12) is provided in order to elevate a pressure of at least some of the liquid phase (22) to a basic pressure, and wherein at least one pressure modulator (13), interposed between the pressure generator (12) and the nozzle (14), is configured to modulate the pressure of at least some of the liquid phase (22) around the basic pressure.

2. The print head (10) as claimed in claim 1, wherein the pressure modulator (13) acts on a partial volume of the liquid phase (22) which has a volume of no more than 1 cm.sup.3 and/or which fills a distance of no more than 5 cm between imparting of the pressure modulation and the discharge opening (15).

3. The print head (10) as claimed in claim 1, wherein the pressure modulator comprises a cylindrical needle (13b) which is movably mounted in a modulator duct (13a) leading to the nozzle (14) and has a tip (13c) tapering toward the nozzle (14).

4. The print head (10) as claimed in claim 3, wherein the tip (13c) is dimensioned such that the tip can be introduced at least partially into the nozzle (14).

5. The print head (10) as claimed in claim 4, wherein the tip (13c) is dimensioned such that the tip can at least partially pass through the discharge opening (15).

6. The print head (10) as claimed in claim 1, wherein the pressure generator (12) comprises a cylindrical piston (12b) which is movably mounted in a main duct (12a) which can be filled with the liquid phase (22).

7. The print head (10) as claimed in claim 6, wherein the pressure modulator comprises a cylindrical needle (13b) which is movably mounted in a modulator duct (13a) leading to the nozzle (14) and has a tip (13c) tapering toward the nozzle (14), wherein the ratio of a diameter of the needle (13b) outside a region of the tip (13c) to the diameter of the piston (12b) is 1:3 or smaller.

8. The print head (10) as claimed in claim 1, wherein the pressure generator (12) and the pressure modulator (13) act on the liquid phase (22) inside a heatable build chamber (16) of the 3D printer (1) for the object (3) to be produced and are mechanically coupled to at least one drive source (12*, 13*) arranged outside the build chamber (16).

9. The print head (10) as claimed in claim 1, wherein at least some of a region in which the pressure generator (12) can increase a pressure of the raw material (20) has a heater (17) for generating a liquid phase (22) of the raw material (20) and the drive source (13*) for the pressure modulator (13) is thermally insulated (18) from this heater (17).

10. The print head (10) as claimed in claim 1, wherein the pressure modulator (13) is configured to lower the pressure of the liquid phase (22) at the discharge opening (15) to such an extent that the discharge of the liquid phase (22) from the discharge opening (15) is prevented.

11. The print head (10) as claimed in claim 7, wherein the tip (13c) is dimensioned such that the tip can be introduced at least partially into the nozzle (14).

12. The print head (10) as claimed in claim 11, wherein the tip (13c) is dimensioned such that the tip can at least partially pass through the discharge opening (15).

13. The print head (10) as claimed in claim 6, wherein the pressure modulator comprises a cylindrical needle (13b) which is movably mounted in a modulator duct (13a) leading to the nozzle (14) and has a tip (13c) tapering toward the nozzle (14), wherein the ratio of a diameter of the needle (13b) outside a region of the tip (13c) to the diameter of the piston (12b) is 1:4 or smaller.

14. The print head (10) as claimed in claim 13, wherein the tip (13c) is dimensioned such that the tip can be introduced at least partially into the nozzle (14).

15. The print head (10) as claimed in claim 14, wherein the tip (13c) is dimensioned such that the tip can at least partially pass through the discharge opening (15).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Further measures which improve the invention are illustrated below in detail with the aid of drawings, together with the description of the preferred exemplary embodiments of the invention.

[0030] FIG. 1 shows an exemplary embodiment of a 3D printer with a build chamber for the object to be produced;

[0031] FIG. 2 shows an exemplary embodiment of a 3D printer with an insulation between the heated pressure generator and the actuator of the pressure modulator.

DETAILED DESCRIPTION

[0032] FIG. 1 shows an exemplary embodiment of a 3D printer 1 with the print head 10. The 3D printer 1 has a heatable build chamber 16 for the object 3 to be produced on a build surface 19. The print head 10 comprises components arranged both inside and outside the build chamber 16.

[0033] The print head 10 comprises a feeder 11 for the raw material 20 which in this exemplary embodiment is supplied in a granular solid phase 21. The solid phase 21 of the raw material 20 is plasticized to form a liquid phase 22 in a pressure generator 12 provided with a heater 17. The pressure generator 12 comprises a main duct 12a in which a piston 12b is guided and a drive source 12* for the piston 12b. The main duct 12a and the piston 12b are guided through the insulation of the build space 16 to the drive source 12* arranged outside the build space 16.

[0034] The pressure generator 12 elevates the pressure of the liquid phase 22 of the raw material 20 to a basic pressure. The print head has a nozzle 14 with a discharge opening 15 through which the liquid phase 22 can be discharged from the print head in the direction of the object 3 to be produced. Starting from the basic pressure, the pressure of the liquid phase 22 is modulated by the pressure modulator 13 interposed between the pressure generator 12 and the nozzle 14. This pressure modulator 13 comprises a modulator duct 13a in which a needle 13b with a tip 13c tapering toward the nozzle 14 is guided. The needle 13b can here enclose in particular a portion of the liquid phase 22 between it and the discharge opening 15. As indicated in FIG. 1, this portion can here not be subject in particular to further influence by the pressure from the pressure generator 12. The pressure modulator 13 can thus increase but also decrease the pressure of the said portion in order, for example, to temporarily prevent the dispensing of liquid raw material 22. It can consequently in particular be avoided, for example, that threads are pulled from liquid raw material 22 discharged undesirably from the discharge opening 15 in the case of lateral movements between the print head 10 and the object 3 to be produced.

[0035] The duct 13a and the needle 13b are guided through the insulation of the build space 16 to the drive source 13* arranged outside the build space 16. Beyond this insulation, the temperature of the needle 13b falls quickly. If therefore some of the liquid phase 22 of the raw material 20 penetrates an intermediate space between the needle 13b and the modulator duct 13a owing to an imprecise fit, this material very quickly becomes so viscous that it cannot penetrate the drive source 13*.

[0036] FIG. 2 shows a further exemplary embodiment of a 3D printer 1 with the print head 10. In contrast to FIG. 1, in this exemplary embodiment there is no thermally insulated build space 16. Instead, the build plate 19 for the object 3 to be produced is at room temperature. In a similar fashion to FIG. 1, that part of the pressure generator 12 which can be filled with the liquid phase 22 of the raw material 20 can be heated with a heater 17. The drive source 13* of the pressure modulator 13 is then protected by a thermal insulation 18 from the heat emitted by the heater 17.